Printed on Recycled Paper

United States Office of Air Quality EPA-453/R-97-004

Environmental ProtectionPlanning and Standards December 1997

Agency Research Triangle Park, NC 27711

Air

EPA Guideline Series

Control of Volatile Organic

Compound Emissions from Coating

Operations at Aerospace

Manufacturing and Rework

Operations
Guideline Series:

Control of Volatile Organic Compound

Emissions from Coating Operations at

Aerospace Manufacturing and Rework

Operations

Emission Standards Division

U. S. Environmental Protection Agency

Office of Air and Radiation

Office of Air Quality Planning and Standards

Research Triangle Park, NC 27711

December 1997
iii

This report has been reviewed by the Emission Standards

Division of the Office of Air Quality Planning and Standards, EPA and

approved for final publication. Mention of trade names or commercial

products is not intended to constitute endorsement or recommendation

for use. The guideline series of reports is issued by the Office of

Air Quality Planning and Standards (OAQPS) to provide information to

State and local air pollution control agencies; for example, to

provide guidance on the acquisition and processing of air quality

data and on the planning and analysis requisite for the maintenance

of air quality. Reports published in this series will be available

from the Library Services Office (MD-35), U. S. Environmental

Protection Agency, Research Triangle Park, North Carolina 27711; from

the Office of Air Quality Planning and Standards Technology Transfer

Network, U. S. Environmental Protection Agency, Research Triangle

Park, North Carolina 27711; or, for a fee, from the National

Technical Information Services, 5285 Port Royal Road, Springfield,

Virginia 22161.

Publication No. EPA-453/R-97-004
iv
v

TABLE OF CONTENTS

Page

1.0 INTRODUCTION ................... 1-1

2.0 AEROSPACE MANUFACTURING AND REWORK OPERATIONS . . 2-1

2.1 GENERAL ................... 2-1

2.2 PROCESS DESCRIPTION ............. 2-3

2.2.1 Coating Application ......... 2-3

2.2.2 Cleaning ............... 2-6

3.0 EMISSION CONTROL TECHNIQUES ........... 3-1

3.1 COATING SUBSTITUTIONS ............ 3-1

3.2 EQUIPMENT CHANGES .............. 3-2

3.2.1 High Transfer Efficiency Spray Guns . 3-2

3.2.2 Spray Gun Cleaning .......... 3-5

3.2.3 Conventional High Transfer Efficiency

Application Methods ......... 3-6

3.3 HAND-WIPE CLEANER SUBSTITUTIONS ....... 3-7

3.3.1 Aqueous and Semiaqueous ....... 3-7

3.3.2 Citrus-Based ............. 3-7

3.3.3 Reduced Vapor Pressure ........ 3-8

4.0 PRESUMPTIVE RACT REQUIREMENTS .......... 4-1

4.1 SPECIALTY COATINGS ............. 4-1

4.2 PRIMERS, TOPCOATS, CHEMICAL MILLING

MASKANTS .................. 4-3

4.3 APPLICATION EQUIPMENT ............ 4-3

4.3.1 Exemptions .............. 4-3

4.3.2 Timing (Schedule) of Compliance ... 4-4

4.4 CLEANING OPERATIONS ............. 4-4

4.4.1 Housekeeping ............. 4-4

4.4.2 Hand-Wipe Cleaning .......... 4-5

4.4.3 Flush Cleaning ............ 4-6

4.4.4 Spray Gun Cleaning .......... 4-6

5.0 GUIDANCE TO STATE ENFORCEMENT AGENCIES ...... 5-1

5.1 DEFINITIONS ................. 5-1

5.2 APPLICABILITY ................ 5-2

5.3 COMPLIANCE, MONITORING, RECORDKEEPING & 

REPORTING PROVISIONS ............ 5-2

APPENDIX A DEFINITIONS ............. A-1

APPENDIX B AEROSPACE MANUFACTURING AND REWORK

OPERATIONS MODEL RULE ........ B-1
vi

LIST OF FIGURES

Page

Figure 2-1. Active U.S. aerospace manufacturing 

facilities ................ 2-4

LIST OF TABLES

Page

TABLE 2-1. AEROSPACE MANUFACTURING SIC CODES .... 2-2

TABLE 3-1. PERCENT REDUCTION IN COATING (PRIMERS

AND TOPCOATS) EMISSIONS WITH HIGH

TRANSFER EFFICIENCY EQUIPMENT FROM 

SECTION 114 DATA ............. 3-4

TABLE 4-1. SPECIALTY COATINGS VOC CONTENT 

LIMITS .................. 4-2
1-1

1.0 INTRODUCTION

The Clean Air Act (CAA) as amended in 1990 requires that State

implementation plans (SIP's) for certain ozone nonattainment areas be

revised to require the implementation of reasonably available control

technology (RACT) to control volatile organic compound (VOC)

emissions. The U. S. Environmental Protection Agency (EPA) has

defined RACT as the lowest emission limitation that a particular

source is capable of meeting by the application of control technology

that is reasonably available considering technological and economic

feasibility. The EPA has issued, and is continuing to issue, control

techniques guideline documents (CTG's) that present feasible RACT

control measures for VOC source categories. The CTG's recommend

"presumptive norms" of control for each source category, but

individual sources may have alternative RACT requirements imposed by

making an adequate infeasibility demonstration (44 FR 53761,

September 17, 1979).

Section 183(b)(3) of the CAA requires the EPA Administrator to

issue a CTG for the control of VOC emissions from coatings and

solvents used in the aerospace industry. This CTG is intended to

supersede any potential applicability of the Miscellaneous Metal Part

and Products CTG (RACT) requirements for manufacturing and rework

operations of aerospace vehicles and components. According to the

CAA, this CTG guidance should also reflect control resulting from

applying the "best available control (BAC) measures." 

Section 183(e)(1)(A) defines "BAC" as the "most effective equipment,
1-2

measures, processes, methods, systems or techniques, including

chemical reformulation, product or feedstock substitution,

repackaging, and directions for use, consumption, storage, or

disposal." Therefore, this CTG departs from the approach followed in

the other CTG's by not recommending a single approach for determining

RACT, but investigating a range of approaches to reduce VOC emissions

from aerospace operations. Several optional approaches comprise the

presumptive RACT found in this CTG.

The CTG's are intended to provide State and local air pollution

control authorities with an information base for proceeding with

their analyses of RACT for their own regulations. The CTG's contain

a review of current knowledge and data concerning the technology,

impacts, and costs associated with various emission control

techniques. Where applicable, the EPA recommends that States adopt

requirements consistent with the presumptive RACT. However, these

measures are only a recommendation; States may develop their own RACT

requirements on a case-by-case basis, considering the economic and

technical circumstances of individual sources. It should be noted

that no Federal laws or regulations preclude States from requiring

more stringent controls than those recommended as RACT. A particular

State, for example, may broaden the applicability by revising the

"aerospace vehicle or component" definition to include models, mockups, prototypes, and production equipment such as molds, jigs, and

tooling. Some States may need additional control in order to meet

the national ambient air quality standards (NAAQS) for ozone in some

areas.

This CTG identifies presumptive RACT for controlling VOC

emissions from aerospace coatings and cleaning solvents. National

emission standards for hazardous air pollutants (NESHAP) for

aerospace manufacturing and rework operations were published on

September 1, 1995 (60 FR 45948). While these final standards address
1-3

the reduction of HAP emissions, the control techniques required by

the NESHAP will result in reductions of VOC emissions as well. In

addition, the control techniques required by the NESHAP are similar

to those addressed in this CTG for reducing VOC emissions. Because

the emission reductions, costs, and environmental impacts have

already been determined for major HAP sources and are attributed to

the NESHAP (see Docket No. A-90-20, Subcategory II-B), these impacts

are not summarized in this CTG.

While the Aerospace NESHAP sets limits for maximum HAP and VOC

content for topcoats, primers, maskants, clean-up solvents, and

cleaning operations, the CTG establishes presumptive RACT limits for

VOC's. The CTG includes requirements for Specialty Coatings, which

are not covered by the Aerospace NESHAP. The Clean Air Act specifies

that solvents will be addressed in the Aerospace CTG. However,

because the CTG is guidance to be adopted as individual State

regulations and SIP's, it does not specify detailed requirements for

monitoring, testing, recordkeeping, and reporting as the NESHAP has

done. Rather, the States are directed under previous EPA guidance

for establishing RACT (57 FR 13502, April 16, 1992) to develop

"enforceable regulations" containing such requirements. While EPA is

providing an example of such a regulation in the model rule

(Appendix B), this CTG allows States the flexibility to address those

requirements as long as they meet EPA enforceability criteria.
2-1

2.0 AEROSPACE MANUFACTURING AND REWORK OPERATIONS

2.1 GENERAL

The aerospace industry being evaluated includes all

manufacturing facilities that produce an aerospace vehicle or

component and all facilities that rework or repair these aerospace

products. Aerospace vehicle or component is defined as, but not

limited to, any fabricated part, processed part, assembly of parts,

or completed unit of any aircraft including, but not limited to,

airplanes, helicopters, missiles, rockets, and space vehicles. In

addition to manufacturing and rework facilities, some shops may

specialize in providing a service, such as chemical milling, rather

than actually producing a component or assembly. In general,

aerospace manufacturing and rework facilities are covered by the SIC

codes listed in Table 2-1. However, facilities classified under

other SIC codes may be subject to the proposed rule if the facility

meets the definition of a major source and the definition of an

aerospace manufacturing or rework facility.
2-2

TABLE 2-1. AEROSPACE MANUFACTURING SIC CODES

SIC Code Description

3720 Aircraft and Parts

3721 Aircraft

3724 Aircraft Engines and Engine Parts

3728 Aircraft Parts and Equipment

3760 Guided Missiles, Space Vehicles, and Parts

3761 Guided Missiles and Space Vehicles

3764 Space Propulsion Units and Parts

3769 Space Vehicle Equipment

4512 Air Transportation, Scheduled

4581 Airports, Flying Fields, and Services

9711 National Security

Aerospace facilities may be divided into four market segments: 

commercial original equipment manufacturers (OEM), commercial rework

facilities, military OEM's, and military rework facilities. The

commercial OEM segment of the market includes the manufacture of

commercial aircraft as well as the production of business and private

aircraft. The military OEM segment of the market includes military

installations and defense contractors that manufacture aircraft,

missiles, rockets, satellites, and spacecraft. Rework facilities,

both commercial and military, may rework many of the above end

products.

Based on information obtained through the Federal Aviation

Administration and the U.S. Department of Commerce - Bureau of the

Census, there are an estimated 2,869 aerospace facilities that could

be subject to this guidance. Of this number, 1,395 produce or rework

commercial products, and 1,474 produce or rework military products. 
2-3

The combined VOC emissions from these facilities are estimated to be

over 213,000 megagrams/year (Mg/yr) (234,000 tons/yr).

In addition to these facilities, there are numerous

subcontractors that manufacture or rework aerospace vehicles or

components. The subcontractors may work directly for the OEM or

rework facilities, or indirectly through first line subcontractors. 

Because most of these subcontractors perform various types of work,

they are often classified under non-aerospace SIC codes. 

Consequently, an estimate of the number of subcontractors cannot be

made. One company alone, however, employs the services of over

5,000 subcontractors.

Aerospace manufacturing facilities and rework operations

typically are located in or near industrial centers in areas of

medium to high population density. Some States with a large number

of aerospace manufacturers are California, Texas, Connecticut,

Florida, and Washington. Figure 2-1 presents the number of aerospace

manufacturing facilities by State.
2-4
2-5
2-6

Aerospace manufacturing facilities range in size from small

shops that produce a single aerospace component, such as propellers,

to large corporations that produce the entire aircraft. Aerospace

rework facilities, however, are usually large facilities that must be

able to rework or repair every facet of several models of large

commercial or military aircraft.

The hours of operation at aerospace manufacturing and rework

facilities may vary greatly due to the production backlog at each

facility. The hours of operation may range from 8 hours (or less)

per day, 5 days per week, to 24 hours per day, 7 days per week. 

2.2 PROCESS DESCRIPTION

Aerospace manufacturing and rework operations typically consist

of the following basic operations: materials receiving, machining

and mechanical processing, coating application, chemical milling,

heat treating, cleaning, metal processing and finishing, coating

removal (depainting), composite processing, and testing. Many

aerospace manufacturing and rework facilities may employ all of these

processes in their operations, as with an OEM facility that produces

the entire aerospace vehicle. However, an aerospace facility may

only employ a subset of these operations, as with a facility that

produces a single component or assembly or a facility that provides a

service such as chemical milling. Of these operations, coating

application and cleaning are the significant sources of VOC emissions

and are the processes covered by this Aerospace CTG in the following

sections.

2.2.1 Coating Application

A coating is a material that is applied to the surface of a

part to form a decorative, protective, or functional solid film. The

most common coatings are the broad categories of nonspecialized

primers and topcoats that are regulated for major sources under the
2-7

Figure 2-1. Active U.S. aerospace manufacturing facilities.

Aerospace NESHAP. There are also numerous specialty coatings covered

by this guidance that provide 
2-8

additional performance characteristics, such as temperature, fluid,

fire resistance, flexibility, substrate compatibility,

antireflection, temporary protection or marking, sealing, adhesively

joining substrates, enhanced corrosion protection, or compatibility

with a space environment. Each material is different because it must

meet individual performance standards particular to a specific

design. The quality of the coatings is critical to the airworthiness

and safety of the final product. Aerospace vehicle manufacturing is

strictly controlled by the Federal Aviation Administration, the

Department of Defense, and specific customer requirements. Industry

specifications for coatings are dictated by these requirements.

Most aerospace coatings are solvent-borne, which contain a

mixture of organic solvents, many of which are VOC's. The most

common VOC solvents used in coatings are toluene, xylene, methyl

ethyl ketone, and methyl isobutyl ketone. The VOC content ranges

differ for the various coating categories.

2.2.1.1 SealingSealants, predominately composed of

polysulfide, are applied throughout the aerospace vehicle structure

primarily to seal out moisture and contaminants to prevent corrosion,

such as on faying (i.e., closely or tightly fitting) surfaces, inside

holes and slots, and around installed fasteners. They are also used

to seal fuel tanks and pressurized components. Sealants are applied

using tubes, spatulas, brushes, rollers, or spray guns. Sealants are

often stored frozen and thawed before use, and many are two-component

mixtures that cure after mixing. Typically, a sealant is applied

before assembly or fastener installation, and the excess is squeezed

out or extruded from between the parts as the assembly is completed. 

This ensures a moisture-tight seal between the parts.. 

2.2.1.2 Adhesive BondingAdhesive bonding involves joining

together two or more metal or nonmetal components. This process is

typically performed when the joints being formed are essential to the
2-9

structural integrity of the aerospace vehicle or component. Bonding

surfaces are typically roughened mechanically or etched chemically to

provide increased surface area for bonding and then treated

chemically to provide a stable corrosion-resistant oxide layer. The

surfaces are then thinly coated with an adhesive bonding primer to

promote adhesion and protect from subsequent corrosion. Structural

adhesives are applied as either a thin film or as a paste. The parts

are joined together and cured either at ambient temperature, in an

oven, or in an autoclave to cure the adhesive and provide a permanent

bond between the components.. 

Nonstructural adhesives are used to bond materials that are not

critical to the structural integrity of the aerospace vehicle or

component, such as gaskets around windows and carpeting or to

nonstructurally joined components. These adhesives are applied using

tubes, brushes, and spray guns. 

2.2.2 Cleaning

Cleaning agents for hand-wipe, flush, and spray equipment

cleaning consist of solvents such as methyl ethyl ketone, methyl

isobutyl ketone, toluene, various solvent blends, or alkaline

materials.

2.2.2.1 Hand-Wipe and Flush CleaningAerospace components are

cleaned frequently during manufacturing to remove contaminants such

as dirt, grease, and oil, and to prepare the components for the next

operation. Cleaning is typically performed by a hand wiping process

using a wide variety of cleaning solvents. Assemblies and parts with

concealed or inaccessible areas may be flush-cleaned by passing the

cleaning agent over, into, or through the part. The cleaning agent

is then drained from the part and the procedure is repeated as many

times as necessary to ensure the required cleanliness.. 

2.2.2.2 Spray Gun and Coating Line CleaningSpray guns and

coating lines used to apply the various coatings used at aerospace
2-10

facilities must be cleaned when switching from one coating to another

and when they are not going to be immediately reused. Spray guns can

be cleaned either manually or with enclosed spray gun cleaners. 

Manual cleaning involves disassembling the gun and placing the parts

in a vat containing an appropriate cleaning solvent. The residual

paint is brushed or wiped off the parts. After reassembling, the

cleaning solvent may be sprayed through the gun for a final cleaning. 

Paint hoses/coating lines are cleaned by passing the cleaning solvent

through the lines until all coating residue is removed.Enclosed

spray gun cleaners are self-contained units that pump the cleaning

solvent through the gun within a closed chamber. After the cleaning

cycle is complete, the guns are removed from the chamber and

typically undergo some manual cleaning to remove coating residue from

areas not exposed to the cleaning solvent, such as the seals under

the atomizing cap.. 
3-1

3.0 EMISSION CONTROL TECHNIQUES

The principal technique used by the aerospace industry to

control VOC emissions from coating application and cleaning is

product substitution, which eliminates or reduces the generation of

emissions. The emission reduction is obtained using less energy and

producing less waste than using a control device to achieve the same

emission reductions.

The VOC emissions may be controlled by replacing products

containing high concentrations of VOC's with ones that have reduced

or eliminated VOC's. Different aerospace manufacturers use different

processes to produce their product. Therefore, they typically have

different specifications for the coatings and cleaning solvents used

on the components of the end products. Each individual facility must

evaluate the ability of the new product to maintain standards of

quality and performance. In addition, the potential overall

environmental benefit of the reformulated products must be carefully

evaluated.

The following sections describe the available product

substitutions for coatings and cleaning solvents. While alternative

methods, such as control devices (carbon adsorbers, incinerators,

etc.), are occasionally used to reduce emissions, they do not

represent RACT and are, therefore, not discussed below. 
3-2

3.1 COATING SUBSTITUTIONS

Waterborne and high solids materials are generally used for

coating substitutions. Specialty coatings typically have relatively

low usage, so reformulation to lower VOC contents does not produce

significant air quality benefits nor is it economically feasible for

the paint suppliers. Paint suppliers and the aerospace industry

generally have targeted high volume materials for reformulation

efforts. Therefore, lower VOC formulations are not available for

most of the low volume specialty coating categories. 

3.2 EQUIPMENT CHANGES

The aerospace industry has implemented several equipment

changes that directly reduce the level of VOC emissions. While there

are equipment changes that effect emissions from every process, the

three changes predominantly used in the industry are high transfer

efficiency spray guns, spray gun cleaners, and conventional high

transfer efficiency methods. Each of these equipment changes are

discussed below.

3.2.1 High Transfer Efficiency Spray Guns

Emissions from spray coating operations can be reduced through

the use of spraying systems with higher transfer efficiency. 

Transfer efficiency, expressed as a percentage, can be defined as the

ratio of coating solids actually applied to the surface of the

component being coated to the amount of solids released from the

spray gun. Spraying systems with a higher transfer efficiency can

coat the same surface area using less coating. Therefore, the VOC

emissions resulting from the use of this equipment are reduced

compared to applying the same coating with conventional spray

equipment. The transfer efficiency values reported in this section

depend on coating sprayed, part configuration, spray booth air

velocity, and other variables.
3-3

Most aerospace components are coated using manual spray

equipment utilizing conventional airspray or airless spraying

technology. The following sections discuss two types of high

transfer coating application equipment generally used in the

aerospace industry for the application of primers and topcoats: high

volume, low pressure (HVLP) and electrostatic (use of these types of

high transfer efficiency for specialty coatings is limited).

3.2.1.1 High Volume Low Pressure Spray GunsHigh volume low

pressure and electrostatic spraying systems are the primary high

efficiency spray methods used by the industry. High volume low

pressure spray guns use high volumes [10 to 25 standard cubic feet

per minute (scfm)] of low pressure [2 to 10 pounds per square inch

gauge (psig)] air to deliver the paint. The lower air pressure

creates a lower particle speed, resulting in a more controlled spray

pattern with less overspray and bounce back from the substrate, thus

improving transfer efficiency.. 

High volume low pressure systems have been in use in the United

States for approximately 10 years. In early systems, turbines were

used to supply a high volume of low pressure air to the spray guns

through large hoses. The second generation used compressed air with

an air regulator to maintain the required low pressure. The third

and current generation of HVLP equipment uses restrictors within the

gun to reduce the atomization pressure to a maximum of 10 psi at the

air cap.

One disadvantage of HVLP spray guns is that some very high

solids coatings are difficult to atomize due to their higher

viscosities. However, when a turbine is used, the temperature of the

atomizing air increases which aids in reducing the viscosity of the

coating. Other disadvantages of HVLP spray guns are that they cannot

be used with extension nozzles, and they may slow production rates

because of the low fluid delivery rates.
3-4

It is estimated that HVLP can apply approximately 80 percent of

the coating currently used in the aerospace industry, including

primers, waterborne coatings, and both single and two-component

topcoats. A medium commercial/rework facility utilizes HVLP

equipment with high solids paint and has had a reduction of 22 to

30 percent in coating usage for various aircraft types. The HVLP

technology has proven easy to use and maintain. It also provides

high transfer efficiency and appears to be the preferred spray

technology in the aerospace industry at this time.
3-5

Table 3-1
3-6

TABLE 3-1. PERCENT REDUCTION IN COATING EMISSIONS

(PRIMERS AND TOPCOATS) WITH HIGH TRANSFER

EFFICIENCY EQUIPMENT FROM SECTION 114 DATA

Size Commercial or military OEM or rework High transfer equipment % Reduction in emissions

Large Military OEM HVLP 20

Large Military OEM HVLP 20

Large Military OEM HVLP 25

Large Commercial OEM Unspecified 30

Large Commercial OEM Unspecified 18

Medium Commercial

Military

Military

OEM

OEM

Rework

HVLP 25

Medium Commercial

Military

Military

OEM

OEM

Rework

HVLP 20-40

Medium Military OEM HVLP and electrostatic 40

Medium Military OEM HVLP and electrostatic 40

Medium Military OEM HVLP 40

Medium Military OEM HVLP 10

Medium Military

Military

OEM

Rework

Electrostatic 30-40

Medium Military Rework HVLP and electrostatic 35-40

Medium Commercial OEM Unspecified 30

Medium Commercial OEM Unspecified 33

Medium Commercial Rework HVLP and electrostatic 50

Medium Commercial Rework HVLP and high solids 22% for large aircraft

25% for medium aircraft

30% for small aircraft

Small Commercial OEM Unspecified 30

Small Commercial

Military

OEM

OEM

HVLP 28
3-7

 shows the reduction in emissions obtained from the Section 114

questionnaire responses from various facilities utilizing high

transfer efficiency equipment such as HVLP or electrostatic

equipment, either alone, in conjunction with each other, or, in one

case, HVLP equipment with high solids coatings.
3-8

3.2.1.2 Electrostatic Spray GunsWith electrostatic spray

systems, atomized particles of coating acquire an electric charge as

they pass through a high voltage field at the end of the spray

nozzle. This electric charge causes the particles to be attracted to

the parts being painted, which are electrically grounded. Although

other substrates can be pretreated with conductive coatings, this

technology is primarily used for metal parts. The electrostatic

effect can be utilized in conjunction with air spray, airless, and

air-assisted airless systems to enhance the transfer efficiencies of

these basic technologies. See Table 3-1 for examples of percent

reduction obtained at various facilities using electrostatic spray

guns or electrostatic spray guns in combination with HVLP spray

guns.. 

3.2.2 Spray Gun Cleaning

Spray guns are typically cleaned at the end of every job, as

well as between color changes. Manual cleaning of spray guns

involves disassembling the gun and placing the parts in a tray

containing an appropriate cleaning solvent. The residual paint is

brushed or wiped off the parts, then cleaning solvent is sprayed

through the gun after it is reassembled. Various methods are used to

minimize the resulting emissions from spray gun cleaning and are

discussed below.

Enclosed system. Enclosed spray gun cleaners are completely

enclosed units that spray the cleaning solvent through and over the

spray gun. The enclosed unit eliminates most of the exposure of the

cleaning solvent to the air, thereby greatly reducing the VOC

emissions from evaporation.

Nonatomized cleaning. Cleaning solvent is placed in the

pressure pot and forced through the gun with the atomizing cap in

place. No atomizing air is to be used. The cleaning solvent from
3-9

the spray gun is directed into a vat, drum, or other waste container

that is closed when not in use.

Disassembled spray gun cleaning. Manual cleaning (described

above) with the components cleaned by hand in a vat, which is only

closed when not in use. Alternatively, the components are soaked in

a vat, which is closed at all times except when components are being

inserted or removed.

Atomizing cleaning. Cleaning solvent is forced through the

spray gun and the resulting atomized spray is directed into a waste

container that is fitted with a device designed to capture the

atomized solvent emissions.

3.2.3 Conventional High Transfer Efficiency Application Methods

Conventional high transfer efficiency application methods for

primers and topcoats include dip, roll, brush, and flow coating (use

of these methods for specialty coatings is limited). These methods

are discussed below.

Dip Coating. With dip coating application, parts are immersed

into a tank of coating. The parts are then removed from the tank and

held over it until the excess coating drips back into the tank. This

method is simple and allows many different parts to be coated with

high transfer efficiency. However, dip coating is limited to parts

that can fit into the dip tank. Other parts difficult to dip coat

could include complex parts that would trap the coating, allowing

unequal coating thicknesses.

Roll Coating. In roll coating application, a series of

mechanical rollers are used to coat flat surfaces. This method

achieves high efficiency with high rates of application and

automation. However, roll coating is limited to flat parts.

Brush Coating. In brush coating application, brushes and hand

rollers are used to apply the coating manually. This method is used

with operations (e.g., touch-up and detail painting) that cannot
3-10

tolerate the overspray associated with spray gun application. For

example, if a facility needs to paint only the tail section of an

airplane, it may be easier to brush coat this area than to mask the

entire plane to protect the rest of the shell from overspray. This

application method typically involves high labor costs, increased

production time, and poor coating thickness control.

Flow Coating. In flow coating application, the part is

conveyed over a closed sink, and a pumped stream of coating gently

flows over the surface of the part. The excess coating is drained

into the sink, filtered, and pumped to a holding tank for reuse. 

Flow coating is typically limited to flat sheets and noncritical

parts. Coating thickness is difficult to control using flow coating.

3.3 HAND-WIPE CLEANER SUBSTITUTIONS

Product substitutions for hand-wipe cleaning that are prevalent

in the aerospace industry can be classified as aqueous, semiaqueous,

citrus-based, and reduced vapor pressure. Each category is discussed

below.

3.3.1 Aqueous and Semiaqueous

Aqueous and semiaqueous cleaners contain water as the base

component rather than an organic solvent or mixture of solvents. 

Other components may include corrosion inhibitors, alkalinity

builders, and organic surfactants, depending on the desired soil

removal properties. Aqueous and semiaqueous cleaners have been used

in noncritical areas where strict cleanliness requirements do not

have to be met, or where there are no confined spaces that may trap

residues of the cleaner.

The advantages of using aqueous and semiaqueous cleaning

solvents include reduced VOC emissions. Disadvantages are increased

production time due to slower evaporation rates, possible decreased

efficiency, and possible increase in wastewater treatment

requirements. In addition, aqueous cleaners may not be applicable to
3-11

all aerospace parts, especially those components that have small

confined spaces where the cleaner residues cannot be adequately

removed. 

3.3.2 Citrus-Based

Citrus-based terpenes such as d-limonene are the primary

components in many alternative cleaning solutions. While these

solutions have high VOC contents, their vapor pressure is very low,

leading to reduced evaporation rates. These cleaners have been found

to be effective in some cleaning operations except for cleaning prior

to adhesive bonding. Some disadvantages include possible worker

sensitivity, VOC emissions, lack of rinseability in water, and

increased production time due to slower evaporation rates. 

3.3.3 Reduced Vapor Pressure

Reduced vapor pressure cleaning solvents have a maximum VOC

composite vapor pressure of 45 millimeters of mercury (mmHg) at 20°C. 

Cleaning solvent emissions are reduced because their lower vapor

pressure leads to reduced evaporation rates. These cleaners are

effective in many cleaning operations except for some limited

operations such as cleaning oxygen systems.
4-1

4.0 PRESUMPTIVE RACT REQUIREMENTS

The presumptive RACT requirements for the aerospace component

and vehicle cleaning and coating operations are described in the

following sections. The operations covered by this CTG shall not be

subject to another CTG. The operations and applications exempted

under this CTG shall not be subject to another CTG. Applicable

definitions are included in Appendix A.

These presumptive RACT requirements do not apply to

manufacturing or rework operations involving space vehicles; rework

operations performed on antique aerospace vehicles or components; or

to the following activities where cleaning and coating of aerospace

components and vehicles may take place: research and development,

quality control, laboratory testing, and electronic parts and

assemblies (except for cleaning and coating of completed assemblies). 

4.1 SPECIALTY COATINGS

Presumptive RACT for coatings used on aerospace components and

vehicles is based on VOC content. Except as provided in Sections 4.0

and 4.1, the presumptive RACT for coating VOC content is the use of

coatings with a VOC content less than or equal to that given in

Table 4-1: Specialty Coatings VOC Content Limits. 
4-2

TABLE 4-1. SPECIALTY COATINGS VOC CONTENT LIMITS (g/L)a

Coating type Limit Coating type Limit

Ablative Coating ................................ 600

Adhesion Promoter .............................. 890

Adhesive Bonding Primers:

Cured at 250°F or below ......................... 850

Cured above 250°F ............................ 1030

Adhesives:

Commercial Interior Adhesive ..................... 760

Cyanoacrylate Adhesive ........................ 1,020

Fuel Tank Adhesive ............................ 620

Nonstructural Adhesive .......................... 360

Rocket Motor Bonding Adhesive ................... 890

Rubber-based Adhesive .......................... 850

Structural Autoclavable Adhesive .................... 60

Structural Nonautoclavable Adhesive ................. 850

Antichafe Coating ............................... 660

Bearing Coating ................................ 620

Caulking and Smoothing Compounds ................. 850

Chemical Agent-Resistant Coating .................... 550

Clear Coating .................................. 720

Commercial Exterior Aerodynamic 

Structure Primer .............................. 650

Compatible Substrate Primer ........................ 780

Corrosion Prevention Compound ..................... 710

Cryogenic Flexible Primer ......................... 645

Cryoprotective Coating ........................... 600

Dry Lubricative Material ........................... 880

Electric or Radiation-Effect Coating ................... 800

Electrostatic Discharge and Electromagnetic

Interference (EMI) Coating ........................ 800

Elevated-Temperature Skydrol-Resistant

Commercial Primer ............................ 740

Epoxy Polyamide Topcoat ......................... 660

Fire-Resistant (interior) Coating ...................... 800

Flexible Primer ................................. 640

Flight-Test Coatings:

Missile or Single Use Aircraft ..................... 420

All Other ................................... 840

Fuel-Tank Coating .............................. 720

High-Temperature Coating ......................... 850

Insulation Covering .............................. 740

Intermediate Release Coating ........................ 750

Lacquer ...................................... 830

Maskants:

Bonding Maskant ............................ 1,230

Critical Use and Line Sealer Maskant ............... 1,020

Seal Coat Maskant ............................ 1,230

Metallized Epoxy Coating ......................... 740

Mold Release .................................. 780

Optical Anti-Reflective Coating ...................... 750

Part Marking Coating ............................ 850

Pretreatment Coating ............................. 780

Rain Erosion-Resistant Coating ...................... 850

Rocket Motor Nozzle Coating ....................... 660

Scale Inhibitor ................................. 880

Screen Print Ink ................................ 840

Sealants:

Extrudable/Rollable/Brushable Sealant ............... 280

Sprayable Sealant ............................. 600

Silicone Insulation Material ........................ 850

Solid Film Lubricant ............................. 880

Specialized Function Coating ....................... 890

Temporary Protective Coating ....................... 320

Thermal Control Coating .......................... 800

Wet Fastener Installation Coating .................... 675

Wing Coating ................................. 850

aCoating limits are expressed in terms of mass (grams) or VOC per volume (liter) of coating less water and less exempt

 solvent.
4-3

Exemptions. The following applications are exempt from the

presumptive RACT coating limits in Table 4-1:

1. Touchup, aerosol, and DOD classified coatings;

2. Coatings used on space vehicles; and

3. Facilities that use separate formulations in volumes of

less than 50 gallons per year, subject to a maximum exemption of

200 gallons for all such formulations applied annually.
4-4

4.2 PRIMERS, TOPCOATS, CHEMICAL MILLING MASKANTS

The broad categories of primers, topcoats (including selfpriming topcoats), and chemical milling maskants (Type I/II) are not

specialty coatings as listed in Table 4-1 and are regulated for major

sources under the Aerospace NESHAP requiring MACT limits with a

compliance date specified in 40 CFR 63.749(a). These limits may be

assumed to represent RACT limits 1 year after the major sources are

required to meet the MACT limits and, therefore, shall not be

effective until 1 year after the NESHAP compliance date of September

1, 1998. The requirements do not apply to facilities that use

separate formulations of primers, topcoats, and chemical milling

maskants (Type I/II) in volumes of less than 50 gallons per year,

subject to a maximum exemption of 200 gallons total for such

formulations applied annually.

4.3 APPLICATION EQUIPMENT FOR PRIMERS AND TOPCOATS

Presumptive RACT for primer and topcoat (including self-priming

topcoats) application equipment used on aerospace components and

vehicles is based on current practices and requirements in some

States. Except as provided in Section 4.3 and Subsection 4.3.1, the

presumptive RACT for primer and topcoat (including self-priming

topcoat) application equipment is the use of one or more of the

following application techniques: flow/curtain coat; dip coat; roll

coating; brush coating; cotton-tipped swab application;

electrodeposition coating; high volume low pressure (HVLP) spraying;

electrostatic spray; or other coating application methods that

achieve emission reductions equivalent to HVLP or electrostatic spray

application methods.

4.3.1 Exemptions

The following situations are exempt from the presumptive RACT

application techniques described in Section 4.3:
4-5

1. Any situation that normally requires the use of an airbrush

or an extension on the spray gun to properly reach limited access

spaces;

2. The application of specialty coatings;

3. The application of coatings that contain fillers that

adversely affect atomization with HVLP spray guns and that the

permitting agency has determined cannot be applied by any of the

application methods specified in Section 4.3;

4. The application of coatings that normally have a dried film

thickness of less than 0.0013 centimeter (0.0005 in.) and that the

permitting agency has determined cannot be applied by any of the

application methods specified in Section 4.3;

5. The use of airbrush application methods for stenciling,

lettering, and other identification markings;

6. The use of hand-held spray can application methods; and

7. Touch-up and repair operations.

4.3.2 Timing (Schedule) of Compliance

The application techniques identified as presumptive RACT are

regulated for major sources under the Aerospace NESHAP requiring MACT

application equipment with a compliance date of September 1, 1998

specified in 40 CFR 63.749(a). These equipment requirements may be

assumed to represent RACT requirements 1 year after the major sources

are required to meet the MACT equipment requirements and, therefore,

shall not be effective until 1 year after the NESHAP compliance date

of September 1, 1998.

4.4 CLEANING OPERATIONS

For solvent cleaning operations, this guidance departs from the

standard presumptive RACT requirement to incorporate MACT level

controls. Therefore, the requirements of Section 4.2 shall not

become effective prior to the Aerospace NESHAP compliance date of

September 1, 1998. The MACT and RACT for solvent cleaning is based
4-6

on work practices and cleaning solvent composition. Except as

provided in Section 4.0 and Subsection 4.4.2, MACT and RACT for

certain activities is described below. 

4.4.1 Housekeeping

All fresh and used cleaning solvents, except semiaqueous

cleaning solvents, used in solvent cleaning operations shall be

stored in containers that shall be kept closed at all times except

when filling or emptying. It is recommended that cloth and paper, or

other absorbent applicators, moistened with cleaning solvents be

stored in closed containers. Cotton-tipped swabs used for very small

cleaning operations are exempt. In addition, the owner or operator

must implement handling and transfer procedures to minimize spills

during filling and transferring the cleaning solvent to or from

enclosed systems, vats, waste containers, and other cleaning

operation equipment that hold or store fresh or used cleaning

solvents. The above requirements are known collectively as

housekeeping measures. Aqueous cleaning solvents are excluded from

these housekeeping requirements. 

4.4.2 Hand-Wipe Cleaning

Hand-wipe cleaning operations require the use of cleaning

solvents which are aqueous or have a VOC composite vapor pressure

less than or equal to 45 millimeters of mercury (mm Hg) at 20°C. 

Exemptions

The following cleaning operations would be exempt from the

cleaning solvent composition and vapor pressure requirements stated

in Section 4.4.2: 

 1. Cleaning during the manufacture, assembly, installation,

maintenance, or testing of components of breathing oxygen systems

that are exposed to the breathing oxygen;

 2. Cleaning during the manufacture, assembly, installation,

maintenance, or testing of parts, subassemblies, or assemblies that
4-7

are exposed to strong oxidizers or reducers (e.g., nitrogen

tetroxide, liquid oxygen, hydrazine); 

 3. Cleaning and surface activation prior to adhesive bonding; 

 4. Cleaning of electronics and assemblies containing

electronics; 

 5. Cleaning of aircraft and ground support equipment fluid

systems that are exposed to the fluid, including air-to-air heat

exchangers and hydraulic fluid systems; 

 6. Cleaning of fuel cells, fuel tanks, and confined spaces; 

 7. Surface cleaning of solar cells, coated optics, and

thermal control surfaces; 

 8. Cleaning during fabrication, assembly, installation, and

maintenance of upholstery, curtains, carpet, and other textile

materials used on the interior of the aircraft; 

 9. Cleaning of metallic and nonmetallic materials used in

honeycomb cores during the manufacture or maintenance of these cores,

and cleaning of the completed cores used in the manufacture of

aerospace vehicles or components; 

10. Cleaning of aircraft transparencies, polycarbonates, or

glass substrates;

11. Cleaning and cleaning solvent usage associated with

research and development, quality control, or laboratory testing;

12. Cleaning operations, using nonflammable liquids, conducted

within 5 feet of energized electrical systems. Energized electrical

systems means any AC or DC electrical circuit on an assembled

aircraft once electrical power is connected, including interior

passenger and cargo areas, wheel wells, and tail sections; and

13. Cleaning operations identified as essential uses under the

Montreal Protocol for which the Administrator has allocated essential

use allowances or exemptions in 40 CFR § 82.4. 
4-8

4.4.3 Flush Cleaning

For cleaning solvents used in the flush cleaning of aerospace

parts, assemblies, and coating unit components, the used cleaning

solvent (except for semiaqueous cleaning solvents) must be emptied

into an enclosed container or collection system that is kept closed

when not in use or captured on wipers and disposed of in accordance

with Section 4.4.1. Aqueous cleaning solvents are excluded from

these flush cleaning requirements. 

4.4.4 Spray Gun Cleaning

All spray guns must be cleaned by one or more of the following

methods: 

1. Enclosed spray gun cleaning system that is kept closed when

not in use, provided that leaks from enclosed spray gun cleaners are

repaired within 14 days from when the leak is first discovered. If

the leak is not repaired by the 15th day after detection, the

cleaning solvent shall be removed and the enclosed cleaner shall be

shut down until the leak is repaired or its use is permanently

discontinued;

2. Unatomized discharge of cleaning solvent into a waste

container that is kept closed when not in use;

3. Disassembled spray gun that is cleaned in a vat and kept

closed when not in use; or

4. Atomized spray into a waste container that is fitted with a

device designed to capture atomized cleaning solvent emissions. 
5-1

5.0 GUIDANCE TO STATE ENFORCEMENT AGENCIES

This chapter presents information for air quality management

agencies to consider in developing an enforceable rule limiting VOC

emissions from coating and solvent cleaning operations at aerospace

manufacturing and rework facilities. The State or other implementing

agency can exercise its prerogative to consider other options

provided that they meet the objectives prescribed in this chapter.

This guidance is for instructional purposes only and, as such,

is not binding. In the development of a State or local aerospace

manufacturing and rework operations rule, the State or other

enforcement agency should consider all information presented in the

CTG and the promulgated NESHAP along with additional information

about specific sources to which the rule will apply. The reasonably

available control technology (RACT) rule, however, should address all

the factors listed in this chapter and in Section 4 to ensure that

the rule has reasonable provisions for demonstrating compliance and

is enforceable. A model rule which contains all these requirements

is provided in Appendix B. The model rule is guidance only and the

State or local agency has the flexibility to adopt alternative

measures, including market-based incentive programs, provided they

meet EPA enforceability criteria. 

5.1 DEFINITIONS

The RACT rule should accurately describe the types of sources

that would be affected and clearly define terms used to describe the

industry or applicable control methods. Example definitions of
5-2

pertinent terms are presented in Appendix A for reference by the

State or local agency. 

5.2 APPLICABILITY

The recommended RACT described in this document applies to the

manufacture of aerospace vehicles and components as well as the

rework or repair of these aerospace products. (See Section 2.) This

guidance has been developed for affected sources in areas of

moderate, serious, or severe nonattainment that have the potential to

emit greater than or equal to 25 tons per year of VOC's. The

guidance is intended to apply to affected sources in extreme areas,

however, if potential VOC emissions are greater than or equal to

10 tons per year. The State or local agency has the flexibility to

apply RACT as deemed necessary. For example, an agency may apply

RACT to all sources that have actual emissions at 50 percent of these

thresholds. 

5.3 COMPLIANCE, MONITORING, RECORDKEEPING & REPORTING PROVISIONS

The State or local agency is responsible for ensuring that

appropriate requirements for compliance determination (testing),

monitoring, recordkeeping and reporting are incorporated into its

RACT rule. These requirements must meet two objectives: (1) the

agency's need to demonstrate VOC emission reductions and (2) EPA's

criteria for enforceability. Because source types, compliance

methods, and agency requirements may vary substantially across the

nation, specific provisions for compliance determination (testing),

monitoring, recordkeeping and reporting are not included in this CTG.

However, for a State's RACT rules to be enforceable, they must

definitively set forth recordkeeping, monitoring, and compliance

determination (testing) requirements appropriate to the type of

source(s) being regulated and sufficient to allow determinations

whether the source(s) are in compliance. Therefore, EPA's Model

Rule, which accompanies this CTG, contains suggested recordkeeping,
5-3

testing, and monitoring provisions that EPA believes are sufficient

to enable EPA and the States to determine compliance with the RACT

requirements of the Model Rule. The State or other implementing

agency can exercise its prerogative to consider various

recordkeeping, testing, and monitoring requirements provided they

meet the objectives prescribed in this CTG. This guidance is for

instructional purposes only and, as such, is not binding.
A-4

APPENDIX A. DEFINITIONS

Terms used in this CTG and the Model Rule in Appendix B are

defined in the Clean Air Act (Act), or in this section as follows:

Ablative coating means a coating that chars when exposed to

open flame or extreme temperatures, as would occur during the failure

of an engine casing or during aerodynamic heating. The ablative char

surface serves as an insulative barrier, protecting adjacent

components from the heat or open flame.

Adhesion promoter means a very thin coating applied to a

substrate to promote wetting and form a chemical bond with the

subsequently applied material.

Adhesive bonding primer means a primer applied in a thin film

to aerospace components for the purpose of corrosion inhibition and

increased adhesive bond strength by attachment. There are two

categories of adhesive bonding primers: primers with a design cure

at 250°F or below and primers with a design cure above 250°F.

Aerosol coating means a hand-held, pressurized, nonrefillable

container that expels an adhesive or a coating in a finely divided

spray when a valve on the container is depressed.

Aerospace vehicle or component means any fabricated part,

processed part, assembly of parts, or completed unit, with the

exception of electronic components, of any aircraft including but not

limited to airplanes, helicopters, missiles, rockets, and space

vehicles.
A-5

Aircraft fluid systems means those systems that handle

hydraulic fluids, fuel, cooling fluids, or oils.

Aircraft transparency means the aircraft windshield, canopy,

passenger windows, lenses and other components which are constructed

of transparent materials.

Antichafe coating means a coating applied to areas of moving

aerospace components that may rub during normal operations or

installation.

Antique aerospace vehicle or component means an aircraft or

component thereof that was built at least 30 years ago. An antique

aerospace vehicle would not routinely be in commercial or military

service in the capacity for which it was designed.

Aqueous cleaning solvent means a solvent in which water is at

least 80 percent of the solvent as applied.

Bearing coating means a coating applied to an antifriction

bearing, a bearing housing, or the area adjacent to such a bearing in

order to facilitate bearing function or to protect base material from

excessive wear. A material shall not be classified as a bearing

coating if it can also be classified as a dry lubricative material or

a solid film lubricant.

Bonding maskant means a temporary coating used to protect

selected areas of aerospace parts from strong acid or alkaline

solutions during processing for bonding.

Caulking and smoothing compounds means semi-solid materials

which are applied by hand application methods and are used to

aerodynamically smooth exterior vehicle surfaces or fill cavities

such as bolt hole accesses. A material shall not be classified as a

caulking and smoothing compound if it can also be classified as a

sealant.
A-6

Chemical agent-resistant coating (CARC) means an exterior

topcoat designed to withstand exposure to chemical warfare agents or

the decontaminants used on these agents.

Chemical milling maskant means a coating that is applied

directly to aluminum components to protect surface areas when

chemical milling the component with a Type I or II etchant. Type I

chemical milling maskants are used with a Type I etchant and Type II

chemical milling maskants are used with a Type II etchant. This

definition does not include bonding maskants, critical use and line

sealer maskants, and seal coat maskants. Additionally, maskants that

must be used with a combination of Type I or II etchants and any of

the above types of maskants (i.e., bonding, critical use and line

sealer, and seal coat) are not included. Maskants that are defined

as specialty coatings are not included under this definition.

Cleaning operation means collectively spray-gun, hand-wipe, and

flush cleaning operations.

Cleaning solvent means a liquid material used for hand-wipe,

spray gun, or flush cleaning. This definition does not include

solutions that contain no VOC.

Clear coating means a transparent coating usually applied over

a colored opaque coating, metallic substrate, or placard to give

improved gloss and protection to the color coat. In some cases, a

clearcoat refers to any transparent coating without regard to

substrate.

Closed-cycle depainting system means a dust free, automated

process that removes permanent coating in small sections at a time,

and maintains a continuous vacuum around the area(s) being depainted

to capture emissions. 

Coating means a material that is applied to the surface of an

aerospace vehicle or component to form a decorative, protective, or

functional solid film, or the solid film itself.
A-7

Coating operation means using a spray booth, tank, or other

enclosure or any area, such as a hangar, for applying a single type

of coating (e.g., primer); using the same spray booth for applying

another type of coating (e.g., topcoat) constitutes a separate

coating operation for which compliance determinations are performed

separately.

Coating unit means a series of one or more coating applicators

and any associated drying area and/or oven wherein a coating is

applied, dried, and/or cured. A coating unit ends at the point where

the coating is dried or cured, or prior to any subsequent application

of a different coating. It is not necessary to have an oven or

flashoff area to be included in this definition.

Commercial exterior aerodynamic structure primer means a primer

used on aerodynamic components and structures that protrude from the

fuselage, such as wings and attached components, control surfaces,

horizontal stabilizers, vertical fins, wing-to-body fairings,

antennae, and landing gear and doors, for the purpose of extended

corrosion protection and enhanced adhesion.

Commercial interior adhesive means materials used in the

bonding of passenger cabin interior components. These components

must meet the FAA fireworthiness requirements.

Compatible substrate primer means either compatible epoxy

primer or adhesive primer. Compatible epoxy primer is primer that is

compatible with the filled elastomeric coating and is epoxy based. 

The compatible substrate primer is an epoxy-polyamide primer used to

promote adhesion of elastomeric coatings such as impact-resistant

coatings. Adhesive primer is a coating that (1) inhibits corrosion

and serves as a primer applied to bare metal surfaces or prior to

adhesive application, or (2) is applied to surfaces that can be

expected to contain fuel. Fuel tank coatings are excluded from this

category. 
A-8

Confined space means a space that (1) is large enough and so

configured that an employee can bodily enter and perform assigned

work; (2) has limited or restricted means for entry or exit (for

example, fuel tanks, fuel vessels, and other spaces that have limited

means of entry); and (3) is not suitable for continuous employee

occupancy.

Corrosion prevention system means a coating system that

provides corrosion protection by displacing water and penetrating

mating surfaces, forming a protective barrier between the metal

surface and moisture. Coatings containing oils or waxes are excluded

from this category.

Critical use and line sealer maskant means a temporary coating,

not covered under other maskant categories, used to protect selected

areas of aerospace parts from strong acid or alkaline solutions such

as those used in anodizing, plating, chemical milling and processing

of magnesium, titanium, or high- strength steel, high-precision

aluminum chemical milling of deep cuts, and aluminum chemical milling

of complex shapes. Materials used for repairs or to bridge gaps left

by scribing operations (i.e., line sealer) are also included in this

category.

Cryogenic flexible primer means a primer designed to provide

corrosion resistance, flexibility, and adhesion of subsequent coating

systems when exposed to loads up to and surpassing the yield point of

the substrate at cryogenic temperatures (-275°F and below).

Cryoprotective coating means a coating that insulates cryogenic

or subcooled surfaces to limit propellant boil-off, maintain

structural integrity of metallic structures during ascent or reentry, and prevent ice formation.

Cyanoacrylate adhesive means a fast-setting, single component

adhesive that cures at room temperature. Also known as "super glue."
A-9

Dry lubricative material means a coating consisting of lauric

acid, cetyl alcohol, waxes, or other noncross linked or resin-bound

materials that act as a dry lubricant.

Electric or radiation-effect coating means a coating or coating

system engineered to interact, through absorption or reflection, with

specific regions of the electromagnetic energy spectrum, such as the

ultraviolet, visible, infrared, or microwave regions. Uses include,

but are not limited to, lightning strike protection, electromagnetic

pulse (EMP) protection, and radar avoidance. Coatings that have been

designated as "classified" by the Department of Defense are exempt.

Electrostatic discharge and electromagnetic interference (EMI)

coating means a coating applied to space vehicles, missiles, aircraft

radomes, and helicopter blades to disperse static energy or reduce

electromagnetic interference.

Elevated-temperature Skydrol-resistant commercial primer means

a primer applied primarily to commercial aircraft (or commercial

aircraft adapted for military use) that must withstand immersion in

phosphate-ester (PE) hydraulic fluid (Skydrol 500b or equivalent) at

the elevated temperature of 150°F for 1,000 hours.

Epoxy polyamide topcoat means a coating used where harder films

are required or in some areas where engraving is accomplished in

camouflage colors.

Exempt solvent means a specified organic compound that has been

determined by the EPA to have negligible photochemical reactivity and

is listed in 40 CFR 51.100. 

Fire-resistant (interior) coating means for civilian aircraft,

fire-resistant interior coatings are used on passenger cabin interior

parts that are subject to the FAA fireworthiness requirements. For

military aircraft, fire-resistant interior coatings are used on parts

that are subject to the flammability requirements of MIL-STD-1630A

and MIL-A-87721. For space applications, these coatings are used on
A-10

parts that are subject to the flammability requirements of SE-R-0006

and SSP 30233.

Flexible primer means a primer that meets flexibility

requirements such as those needed for adhesive bond primed fastener

heads or on surfaces expected to contain fuel. The flexible coating

is required because it provides a compatible, flexible substrate over

bonded sheet rubber and rubber-type coatings as well as a flexible

bridge between the fasteners, skin, and skin-to-skin joints on outer

aircraft skins. This flexible bridge allows more topcoat flexibility

around fasteners and decreases the chance of the topcoat cracking

around the fasteners. The result is better corrosion resistance.

Flight test coating means a coating applied to aircraft other

than missiles or single-use aircraft prior to flight testing to

protect the aircraft from corrosion and to provide required marking

during flight test evaluation.

Flush cleaning means removal of contaminants such as dirt,

grease, oil, and coatings from an aerospace vehicle or component or

coating equipment by passing solvent over, into, or through the item

being cleaned. The solvent may simply be poured into the item being

cleaned and then drained, or assisted by air or hydraulic pressure,

or by pumping. Hand-wipe cleaning operations where wiping,

scrubbing, mopping, or other hand action are used are not included.

Fuel tank adhesive means an adhesive used to bond components

exposed to fuel and must be compatible with fuel tank coatings.

Fuel tank coating means a coating applied to fuel tank

components for the purpose of corrosion and/or bacterial growth

inhibition and to assure sealant adhesion in extreme environmental

conditions.

Grams of VOC per liter of coating (less water and less exempt

solvent) means the weight of VOC per combined volume of total
A-11

volatiles and coating solids, less water and exempt compounds, and

can be calculated by the following equation:

Ws = weight of total volatiles in grams

Ww = weight of water in grams

Wes = weight of exempt compounds in grams

Vs = volume of coating in liters

Vw = volume of water in liters

Ves = volume of exempt compounds in liters 

Hand-wipe cleaning operation means removing contaminants such

as dirt, grease, oil, and coatings from an aerospace vehicle or

component by physically rubbing it with a material such as a rag,

paper, or cotton swab that has been moistened with a cleaning

solvent.

High temperature coating means a coating designed to withstand

temperatures of more than 350°F.

High volume low pressure (HVLP) spray equipment means spray

equipment that is used to apply coating by means of a spray gun that

operates at 10.0 psig of atomizing air pressure or less at the air

cap.

Insulation covering means material that is applied to foam

insulation to protect the insulation from mechanical or environmental

damage.

Intermediate release coating means a thin coating applied

beneath topcoats to assist in removing the topcoat in depainting

operations and generally to allow the use of less hazardous

depainting methods.
A-12

Lacquer means a clear or pigmented coating formulated with a

nitrocellulose or synthetic resin to dry by evaporation without a

chemical reaction. Lacquers are resoluble in their original solvent.

Leak means any visible leakage, including misting and clouding.

Limited access space means internal surfaces or passages of an

aerospace vehicle or component that cannot be reached without the aid

of an airbrush or a spray gun extension for the application of

coatings.

Metalized epoxy coating means a coating that contains

relatively large quantities of metallic pigmentation for appearance

and/or added protection.

Mold release means a coating applied to a mold surface to

prevent the molded piece from sticking to the mold as it is removed.

Nonstructural adhesive means an adhesive that bonds nonload

bearing aerospace components in noncritical applications and is not

covered in any other specialty adhesive categories.

Operating parameter value means a minimum or maximum value

established for a control equipment or process parameter that, if

achieved by itself or in combination with one or more other operating

parameter values, determines that an owner or operator has continued

to comply with an applicable emission limitation.

Optical antireflection coating means a coating with a low

reflectance in the infrared and visible wavelength ranges that is

used for antireflection on or near optical and laser hardware.

Part marking coating means coatings or inks used to make

identifying markings on materials, components, and/or assemblies. 

These markings may be either permanent or temporary.

Pretreatment coating means an organic coating that contains at

least 0.5 percent acids by weight and is applied directly to metal or

composite surfaces to provide surface etching, corrosion resistance,

adhesion, and ease of stripping.
A-13

Primer means the first layer and any subsequent layers of

identically formulated coating applied to the surface of an aerospace

vehicle or component. Primers are typically used for corrosion

prevention, protection from the environment, functional fluid

resistance, and adhesion of subsequent coatings. Primers that are

defined as specialty coatings are not included under this definition.

Radome means the nonmetallic protective housing for.

electromagnetic transmitters and receivers (e.g., radar, electronic

countermeasures, etc.).

Rain erosion-resistant coating means a coating or coating

system used to protect the leading edges of parts such as flaps,

stabilizers, radomes, engine inlet nacelles, etc. against erosion

caused by rain impact during flight.

Research and development means an operation whose primary

purpose is for research and development of new processes and products

and that is conducted under the close supervision of technically

trained personnel and is not involved in the manufacture of final or

intermediate products for commercial purposes, except in a de minimis

manner.

Rocket motor bonding adhesive means an adhesive used in rocket

motor bonding applications.

Rocket motor nozzle coating means a catalyzed epoxy coating

system used in elevated temperature applications on rocket motor

nozzles.

Rubber-based adhesive means a quick setting contact cement that

provide a strong, yet flexible bond between two mating surfaces that

may be of dissimilar materials.

Scale inhibitor means a coating that is applied to the surface

of a part prior to thermal processing to inhibit the formation of

scale.
A-14

Screen print ink means an ink used in screen printing processes

during fabrication of decorative laminates and decals. 

Sealant means a material used to prevent the intrusion of

water, fuel, air, or other liquids or solids from certain areas of

aerospace vehicles or components. There are two categories of

sealants: extrudable/rollable/brushable sealants and sprayable

sealants.

Seal coat maskant means an overcoat applied over a maskant to

improve abrasion and chemical resistance during production

operations.

Self-priming topcoat means a topcoat that is applied directly

to an uncoated aerospace vehicle or component for purposes of

corrosion prevention, environmental protection, and functional fluid

resistance. More than one layer of identical coating formulation may

be applied to the vehicle or component.

Semiaqueous cleaning solvent means a solution in which water is

a primary ingredient (>60 percent of the solvent solution as applied

must be water). 

Silicone insulation material means an insulating material

applied to exterior metal surfaces for protection from high

temperatures caused by atmospheric friction or engine exhaust. These

materials differ from ablative coatings in that they are not

"sacrificial."

Solids means the nonvolatile portion of the coating that after

drying makes up the dry film.

Solid film lubricant means a very thin coating consisting of a

binder system containing as its chief pigment material one or more of

the following: molybdenum, graphite, polytetrafluoroethylene (PTFE),

or other solids that act as a dry lubricant between faying (i.e.,

closely or tightly fitting) surfaces.
A-15

Space vehicle means a man-made device, either manned or

unmanned, designed for operation beyond earth's atmosphere. This

definition includes integral equipment such as models, mock-ups,

prototypes, molds, jigs, tooling, hardware jackets, and test coupons. 

Also included is auxiliary equipment associated with test, transport,

and storage, that through contamination can compromise the space

vehicle performance.

Specialty coating means a coating that, even though it meets

the definition of a primer, topcoat, or self-priming topcoat, has

additional performance criteria beyond those of primers, topcoats,

and self-priming topcoats for specific applications. These

performance criteria may include, but are not limited to, temperature

or fire resistance, substrate compatibility, antireflection,

temporary protection or marking, sealing, adhesively joining

substrates, or enhanced corrosion protection. 

Specialized function coating means a coating that fulfills

extremely specific engineering requirements that are limited in

application and are characterized by low volume usage. This category

excludes coatings covered in other Specialty Coating categories.

Spray gun means a device that atomizes a coating or other

material and projects the particulates or other material onto a

substrate.

Structural autoclavable adhesive means an adhesive used to bond

load-carrying aerospace components that is cured by heat and pressure

in an autoclave.

Structural nonautoclavable adhesive means an adhesive cured

under ambient conditions that is used to bond load-carrying aerospace

components or other critical functions, such as nonstructural bonding

in the proximity of engines.

Surface preparation means the removal of contaminants from the

surface of an aerospace vehicle or component or the activation or
A-16

reactivation of the surface in preparation for the application of a

coating.

Temporary protective coating means a coating applied to provide

scratch or corrosion protection during manufacturing, storage, or

transportation. Two types include peelable protective coatings and

alkaline removable coatings. These materials are not intended to

protect against strong acid or alkaline solutions. Coatings that

provide this type of protection from chemical processing are not

included in this category.

Thermal control coating means a coating formulated with

specific thermal conductive or radiative properties to permit

temperature control of the substrate.

Topcoat means a coating that is applied over a primer on an

aerospace vehicle or component for appearance, identification,

camouflage, or protection. Topcoats that are defined as specialty

coatings are not included under this definition.

Touch-up and repair coating means a coating used to cover minor

coating imperfections appearing after the main coating operation.

Touch-up and repair operation means that portion of the coating

operation that is the incidental application of coating used to cover

minor imperfections in the coating finish or to achieve complete

coverage. This definition includes out-of-sequence or out-of-cycle

coating.

Volatile organic compound (VOC) means any compound defined as

VOC in 40 CFR 51.100. This includes any organic compound other than

those determined by the EPA to be an exempt solvent. For purposes of

determining compliance with emission limits, VOC will be measured by

the approved test methods. Where such a method also inadvertently

measures compounds that are exempt solvent, an owner or operator may

exclude these exempt solvents when determining compliance with an

emission standard.
A-17

VOC composite vapor pressure means the sum of the partial

pressures of the compounds defined as VOC's and is determined by the

following calculation:

Wi = Weight of the "i"th VOC compound, grams.

Ww = Weight of water, grams.

We = Weight of nonwater, non-VOC compound, grams.

MWi = Molecular weight of the "i"th VOC compound, g/g-mole.

MWw = Molecular weight of water, g/g-mole.

MWe = Molecular weight of exempt compound, g/g-mole.

PPc = VOC composite partial pressure at 20°C, mm Hg.

VPi = Vapor pressure of the "i"th VOC compound at 20°C, mm Hg.

Waterborne (water-reducible) coating means a coating which

contains more than 5 percent water by weight as applied in its

volatile fraction.

Wet fastener installation coating means a primer or sealant

applied by dipping, brushing, or daubing to fasteners that are

installed before the coating is cured.

Wing coating means a corrosion-resistant topcoat that is

resilient enough to withstand the flexing of the wings. 
B-1

APPENDIX B. AEROSPACE MANUFACTURING AND REWORK

OPERATIONS MODEL RULE

B.1 APPLICABILITY

(a) Provisions of this Rule

(1) Except as noted in (a)(2) and (a)(3), this rule applies to

the manufacture or rework of commercial, civil, or military aerospace

vehicles or components at facilities located in severe, serious, and

moderate ozone nonattainment areas that have the potential to emit 25

tons per year of VOC or more or are located in extreme nonattainment

areas and have potential to emit 10 tons per year or more.

(2) This rule does not apply to the following activities where

cleaning and coating of aerospace components and vehicles may take

place: research and development, quality control, laboratory

testing, and electronic parts and assemblies (except for cleaning and

coating of completed assemblies). 

(3) This rule does not apply to manufacturing or rework

operations involving space vehicles or rework operations performed on

antique aerospace vehicles or components.

B.2 DEFINITIONS

For the purpose of this rule the definitions listed in

Appendix A shall apply.

B.3 REQUIREMENTS

(a) VOC content of coatings.

(1) A person shall not apply to aerospace vehicles or

components any specialty coatings, including any VOC-containing
B-2

materials added to the original coating supplied by the manufacturer,

that contain VOC in excess of the limits specified below:
B-3
B-4

VOC CONTENT LIMITS FOR SPECIALTY COATINGS (g/L)a

Coating type Limit Coating type Limit

Ablative Coating ............................ 600

Adhesion Promoter .......................... 890

Adhesive Bonding Primers:

Cured at 250°F or below .................... 850

Cured above 250°F ....................... 1030

Adhesives:

Commercial Interior Adhesive ............... 760

Cyanoacrylate Adhesive ................. 1,020

Fuel Tank Adhesive ....................... 620

Nonstructural Adhesive .................... 360

Rocket Motor Bonding Adhesive ............ 890

Rubber-based Adhesive .................... 850

Structural Autoclavable Adhesive ............ 60

Structural Nonautoclavable Adhesive ........ 850

Antichafe Coating ........................... 660

Bearing Coating ............................. 620

Caulking and Smoothing Compounds .......... 850

Chemical Agent-Resistant Coating ............ 550

Clear Coating ............................... 720

Commercial Exterior Aerodynamic 

Structure Primer ........................... 650

Compatible Substrate Primer .................. 780

Corrosion Prevention Compound .............. 710

Cryogenic Flexible Primer ..................... 645

Dry Lubricative Material ..................... 880

Cryoprotective Coating ...................... 600

Electric or Radiation-Effect Coating ............ 800

Electrostatic Discharge and Electromagnetic

Interference (EMI) Coating ................. 800

Elevated-Temperature Skydrol-Resistant

Commercial Primer ......................... 740

Epoxy Polyamide Topcoat .................... 660

Fire-Resistant (interior) Coating ............... 800

Flexible Primer .............................. 640

Flight-Test Coatings:

Missile or Single Use Aircraft ............... 420

All Other ................................. 840

Fuel-Tank Coating ........................... 720

High-Temperature Coating ................... 850

Insulation Covering ......................... 740

Intermediate Release Coating ................. 750

Lacquer .................................... 830

Maskants:

Bonding Maskant ....................... 1,230

Critical Use and Line Sealer Maskant ....... 1,020

Seal Coat Maskant ....................... 1,230

Metallized Epoxy Coating .................... 740

Mold Release ............................... 780

Optical Anti-Reflective Coating ............... 750

Part Marking Coating ........................ 850

Pretreatment Coating ........................ 780

Rain Erosion-Resistant Coating ............... 850

Rocket Motor Nozzle Coating ................. 660

Scale Inhibitor .............................. 880

Screen Print Ink ............................. 840

Sealants:

Extrudable/Rollable/Brushable Sealant ....... 280

Sprayable Sealant ......................... 600

Silicone Insulation Material ................... 850

Solid Film Lubricant ......................... 880

Specialized Function Coating ................. 890

Temporary Protective Coating ................ 320

Thermal Control Coating ..................... 800

Wet Fastener Installation Coating ............. 675

Wing Coating ............................... 850

a Coating limits expressed in terms of mass (grams) of VOC per volume (liters) of coating less water and less exempt solvent.
B-5
B-6

(2) The following coating applications are exempt from the VOC

content limits listed in paragraph (B.3)(a)(1):

(i) Touchup, aerosol, and DoD "classified" coatings

(ii) Coating of space vehicles

(iii) Facilities that use separate formulations in volumes of

less than 50 gallons per year subject to a maximum exemption of

200 gallons total for such formulations applied annually.

(3) Primers, Topcoats, Chemical Milling Maskants. The broad

categories of primers, topcoats (including self-priming topcoats),

and chemical milling maskants (Type I/II) are not specialty coatings

as listed in the table in (B.3)(a)(1) and are regulated for major

sources under the Aerospace NESHAP requiring MACT limits with a

compliance date of September 1, 1998 as specified in

40 CFR 63.749(a). These limits may be assumed to represent RACT

limits 1 year after the major sources are required to meet the MACT

limits and, therefore, shall not be effective until 1 year after the

NESHAP compliance date. The requirements do not apply to facilities

that use separate formulations of primers, topcoats, and chemical

milling maskants (Type I/II) in volumes of less than 50 gallons per

year, subject to a maximum exemption of 200 gallons total for such

formulations applied annually.

(b) Application equipment.

(1) A person shall use one or more of the following

application techniques in applying any primer or topcoat to aerospace

vehicles or components: flow/curtain coat; dip coat; roll coating;

brush coating; cotton-tipped swab application; electrodeposition

coating; high volume low pressure (HVLP) spraying; electrostatic

spray; or other coating application methods that achieve emission

reductions equivalent to HVLP or electrostatic spray application

methods.
B-7

(2) The following situations are exempt from application

equipment requirements listed in paragraph (B.3)(b)(1):

(i) Any situation that normally requires the use of an

airbrush or an extension on the spray gun to properly reach limited

access spaces;

(ii) The application of specialty coatings;

(iii) The application of coatings that contain fillers that

adversely affect atomization with HVLP spray guns and that the

permitting agency has determined cannot be applied by any of the

application methods specified in Section (B.3)(b)(1);

(iv) The application of coatings that normally have a dried

film thickness of less than 0.0013 centimeter (0.0005 in.) and that

the permitting agency has determined cannot be applied by any of the

application methods specified in Section (B.3)(b)(1);

(v) The use of airbrush application methods for stenciling,

lettering, and other identification markings;

(vi) The use of hand-held spray can application methods; and

(vii) Touch-up and repair operations.

(3) The application techniques listed in paragraph (B.3)(b)(1)

are regulated for major sources under the Aerospace NESHAP requiring

MACT application equipment with a compliance date of September 1,

1998 specified in 40 CFR 63.749(a). These equipment requirements may

be assumed to represent RACT requirements 1 year after the major

sources are required to meet the MACT equipment requirements and,

therefore, shall not be effective until 1 year after the NESHAP

compliance date of September 1, 1998.

(c) Solvent cleaning. The following requirements apply to

solvent cleaning operations and shall not be effective until the

Aerospace NESHAP compliance date of September 1, 1998: 

(1) Hand-wipe cleaning. Cleaning solvents used in hand-wipe

cleaning operations shall:
B-8

(i) Meet the definition of aqueous cleaning solvent in

Appendix A, or 

(ii) Have a VOC composite vapor pressure less than or equal to

45 millimeters of mercury (mm Hg) at 20°C.

(2) The following solvent cleaning operations are exempt from

the requirements in paragraph (B.3)(c)(1):

(i) Cleaning during the manufacture, assembly, installation,

maintenance, or testing of components of breathing oxygen systems

that are exposed to the breathing oxygen;

(ii) Cleaning during the manufacture, assembly, installation,

maintenance, or testing of parts, subassemblies, or assemblies that

are exposed to strong oxidizers or reducers (e.g., nitrogen

tetroxide, liquid oxygen, hydrazine);

(iii) Cleaning and surface activation prior to adhesive

bonding;

(iv) Cleaning of electronics parts and assemblies containing

electronics parts;

(v) Cleaning of aircraft and ground support equipment fluid

systems that are exposed to the fluid, including air-to-air heat

exchangers and hydraulic fluid systems;

(vi) Cleaning of fuel cells, fuel tanks, and confined spaces;

(vii) Surface cleaning of solar cells, coated optics, and

thermal control surfaces;

(viii) Cleaning during fabrication, assembly, installation,

and maintenance of upholstery, curtains, carpet, and other textile

materials used on the interior of the aircraft;

(ix) Cleaning of metallic and nonmetallic materials used in

honeycomb cores during the manufacture or maintenance of these cores,

and cleaning of the completed cores used in the manufacture of

aerospace vehicles or components;
B-9

(x) Cleaning of aircraft transparencies, polycarbonate, or

glass substrates;

(xi) Cleaning and solvent usage associated with research and

development, quality control, or laboratory testing;

(xii) Cleaning operations, using nonflammable liquids,

conducted within 5 feet of energized electrical systems. Energized

electrical systems means any AC or DC electrical circuit on an

assembled aircraft once electrical power is connected, including

interior passenger and cargo areas, wheel wells and tail sections;

and,

(xiii) Cleaning operations identified as essential uses under

the Montreal Protocol for which the Administrator has allocated

essential use allowances or exemptions in 40 CFR § 82.4.

(3) Flush cleaning. For cleaning solvents used in the flush

cleaning of parts, assemblies, and coating unit components, the used

cleaning solvent (except for semiaqueous cleaning solvents) must be

emptied into an enclosed container or collection system that is kept

closed when not in use or captured with wipers provided they comply

with the housekeeping requirements of (B.3)(c)(5). Aqueous cleaning

solvents are exempt from these requirements.

(4) Spray gun cleaning. All spray guns must be cleaned by one

or more of the following methods:

(i) Enclosed spray gun cleaning system provided that it is

kept closed when not in use and leaks are repaired within 14 days

from when the leak is first discovered. If the leak is not repaired

by the 15th day after detection, the solvent shall be removed and the

enclosed cleaner shall be shut down until the leak is repaired or its

use is permanently discontinued,

(ii) Unatomized discharge of solvent into a waste container

that is kept closed when not in use,
B-10

(iii) Disassembly of the spray gun and cleaning in a vat that

is kept closed when not in use, or,

(iv) Atomized spray into a waste container that is fitted with

a device designed to capture atomized solvent emissions.

(5) Housekeeping. All fresh and used cleaning solvents,

except semiaqueous cleaning solvents, used in solvent cleaning

operations shall be stored in containers that shall be kept closed at

all times except when filling or emptying. It is recommended that

cloth and paper, or other absorbent applicators, moistened with

cleaning solvents be stored in closed containers. Cotton-tipped

swabs used for very small cleaning operations are exempt. In

addition, the owner or operator must implement handling and transfer

procedures to minimize spills during filling and transferring the

cleaning solvent to or from enclosed systems, vats, waste containers,

and other cleaning operation equipment that hold or store fresh or

used cleaning solvents. The above requirements are known

collectively as housekeeping measures. Aqueous cleaning solvents are

exempt from these requirements. 

(d) Control equipment and monitoring. 

(1) Each owner or operator may comply with the provisions of

paragraph (B.3)(a) by using approved air pollution control equipment

provided that the control system has combined VOC emissions capture

and control equipment efficiency of at least 81 percent by weight.

(2) Each owner or operator shall submit a monitoring plan that

specifies the applicable operating parameter value, or range of

values, to ensure ongoing compliance with (B.3)(d)(1). The

monitoring device shall be installed, calibrated, operated, and

maintained in accordance with the manufacturer's specifications. 

(3) Each owner or operator using an enclosed spray gun cleaner

shall visually inspect the seals and all other potential sources of
B-11

leaks at least once per month. Each inspection shall occur while the

spray gun cleaner is in operation. 

B.4 RECORDKEEPING REQUIREMENTS

(a) Each owner or operator using coatings listed in (B.3)(a)

shall:

(1) Maintain a current list of coatings in use with category

and VOC content as applied.

(2) Record coating usage on an annual basis

(b) Each owner or operator using cleaning solvents required in

(B.3)(c) shall:

(1) For aqueous and semiaqueous hand-wipe cleaning solvents,

maintain a list of materials used with corresponding water contents.

(2) For vapor pressure compliant hand-wipe cleaning solvents:

(i) Maintain a current list of cleaning solvents in use with

their respective vapor pressures or, for blended solvents, VOC

composite vapor pressures.

(ii) Record cleaning solvent usage on an annual basis.

(3) For cleaning solvents with a vapor pressure greater than

45 mm Hg used in exempt hand-wipe cleaning operations:

(i) Maintain a list of exempt hand-wipe cleaning processes.

(ii) Record cleaning solvent usage on an annual basis.

(c) Each owner or operator using control equipment under

paragraph (B.3)(d) shall record monitoring parameters as specified in

the monitoring plan required under (B.3)(d)(2).

(d) Except for Specialty Coatings, any source that complies

with the recordkeeping requirements of the Aerospace NESHAP, 40 CFR

63.752, is deemed to be in compliance with the requirements of this

paragraph (B.4). 
B-12

B.5 TEST METHODS

(a) For coatings which are not waterborne (water-reducible),

determine the VOC content of each formulation (less water and less

exempt solvents) as applied using manufacturer's supplied data or

Method 24 of 40 CFR part 60, Appendix A. If there is a discrepancy

between the manufacturer's formulation data and the results of the

Method 24 analysis, compliance shall be based on the results from the

Method 24 analysis. For water-borne (water-reducible) coatings,

manufacturer's supplied data alone can be used to determine the VOC

content of each formulation.

(b) Cleaning solvents.

(1) For aqueous and semiaqueous cleaning solvents

manufacturers' supplied data shall be used to determine the water

content.

(2) For hand-wipe cleaning solvents required in

paragraph (B.3)(c)(1), manufacturers' supplied data or standard

engineering reference texts or other equivalent methods shall be used

to determine the vapor pressure or VOC composite vapor pressure for

blended cleaning solvents.

(c) Control equipment. Measurements of VOC emissions subject

to paragraph (B.3)(d) shall be conducted in accordance with EPA

Methods 18, 25, and/or 25A (40 CFR 60, Appendix A).

(d) Except for Specialty Coatings, any source which complies

with the test method requirements of the Aerospace NESHAP, 40 CFR

63.750, is deemed to be in compliance with the requirements of this

paragraph (B.5).