Final Staff Report with Appendices for Amendments 

 to Rule 4603 and Rule 4684

SAN JOAQUIN VALLEY UNIFIED AIR POLLUTION CONTROL DISTRICT 

FINAL STAFF REPORT 

Amendments to: 

 Rule 4603 (Surface Coating of Metal Parts and Products) 

 Rule 4684 (Polyester Resin Operations) 

September 17, 2009 

Prepared by: Joven R. Nazareno, Senior Air Quality Engineer 

Reviewed by: George Heinen, Rule Development Supervisor 

Errol Villegas, Planning Manager 

I. SUMMARY 

A. Reasons for Rule Development and Implementation 

The United States Environmental Protection Agency (EPA) and the California Air Resources 

Board (ARB) classified the San Joaquin Valley Air Basin (SJVAB) as a serious and severe 

non-attainment area for the federal and state ozone standards, respectively. Clean Air Act 

(CAA) section 172 (2)(1) provides that state implementation plans (SIPs) for nonattainment 

areas must include reasonably available control technology (RACT), for sources of 

emissions. Section 182 (b)(2) provides for certain nonattainment areas, States must revise 

their SIPs to include RACT for sources of VOC emissions covered by all Control Techniques 

Guidelines (CTG) documents issued after November 15, 1990 and prior to the area’s date of 

attainment. 

CAA section 183(e) directs EPA to list for regulation those categories of products that 

account for at least 80 percent of the VOC emissions, on a reactivity-adjusted basis, from 

consumer and commercial products in areas that violate the national ambient air quality 

standards (NAAQS) for ozone (i.e., ozone nonattainment areas). EPA issued the list on 

March 23, 1995, and continues to revise the list periodically. In September 2008, EPA 

promulgated a new CTG for Miscellaneous Metal and Plastic Parts Coatings (EPA453/R08/003) and a new CTG for Fiberglass Boat Manufacturing Materials (EPA-453/R08-004). CAA section 182(b)(2) requires that a CTG issued between November 15, 1990, 

and the date of attainment include the date by which States subject to section 182(b) must 

submit SIP revisions in response to the CTG. EPA is providing, in said CTGs, a one-year 

period for the required submittal. 

B. Description of the Rule Development Project 

The sole purpose of this rule development project is to amend Rule 4603 (Surface Coating 

of Metal Parts and Products) and Rule 4684 (Polyester Resin Operations) to implement 

RACT requirements as recommended in the CTG for Miscellaneous Metal and Plastic 

Parts Coatings (EPA-453/R08/003) and the CTG for Fiberglass Boat Manufacturing 
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Materials (EPA-453/R-08-004) promulgated by EPA in September 2008, as required by 

the CAA. The CTG for Miscellaneous Metal and Plastic Products would be incorporated 

into Rule 4603 and the CTG for Fiberglass Boat Manufacturing will be incorporated into 

Rule 4684. The CTGs contains VOC content limits, VOC control device efficiency, and 

work practice standards tor educe VOC emissions from these source categories. The 

CTG standards are discussed in Section III of this Final Draft Staff Report.

In developing a CTG, EPA, among other things, evaluates the sources of VOC emissions 

from application processes and the available control approaches for addressing these 

emissions, including the costs of such approaches. Based on available information and 

data, EPA provides recommendations for RACT for miscellaneous metal and plastic 

products and for fiberglass boat manufacturing materials. EPA considers the CTGs to be 

presumptive RACT standards (63 FR 15015, 3/27/98); therefore, the rules will be 

considered RACT after amendments to include the latest CTG requirements. 

II. BACKGROUND 

A. Existing Rule 4603 (Surface Coating of Metal Parts and Products) 

Rule 4603 was last amended in October 2008, which incorporated the 2007 CTG for large 

appliances coatings and 2007 CTG for metal furniture coatings. The rule applies to the 

surface coating of metal parts and products, large appliances parts and products, and 

metal furniture, as well as the solvent cleaning activities associated with coating 

operations. The purpose of the rule is to limit VOC emissions from coating of metal parts 

and products, large appliances parts and products, and metal furniture, and from organic 

cleaning, storage and disposal of solvents and waste solvent materials associated with 

such coating application and solvent cleaning operations. 

The rule specifies separate VOC limits for each category of coatings depending on the type 

of product being coated. The existing rule does not include surface coating of plastic parts 

and products, and pleasure crafts. The 2008 CTG for miscellaneous metal products 

included surface coating of plastic products and pleasure crafts. Rather than developing a 

separate rule, the surface coating of plastic products and pleasure crafts would be 

incorporated into Rule 4603 consistent with the applicability intent of the CTG. 

Rule 4603 allows certain exemptions from the rule or from the coating VOC content limits. 

For example, a facility is exempt from the VOC content limits of the rule if the amount of 

coatings used does not exceed a total of 55 gallons of non-compliant coatings per rolling 

consecutive 365-day period, provided the operator complies with the coating application 

methods and administrative requirements such as recordkeeping. Also coating operations 

that are subject to other District coating rules such as Rule 4661 (Organic Solvents), Rule 

4602 (Motor vehicle and Mobile Equipment Coating Operations), Rule 4612 (Motor Vehicle 

and Mobile Equipment Operations Phase II), and Rule 4605 (Aerospace Assembly and 
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Component Manufacturing Operations) Rule 4604 (Can and Coil Coating Operations). 

Additional exemptions from the rule includes coating operation involving touch-up and 

repair, polyester resin operations and the application of polyester resin to metal parts and 

products. The rule also contains certain exemptions for solvent cleaning operations. 

Rule 4603 establishes VOC content limits for coatings used in the manufacture and 

fabrication of metal parts and products. Except for coatings used on large appliances 

parts and products, and metal furniture coating operations , the general VOC limits for 

baked coating and for air-dried coating is 275 grams per liter (2.3 pounds/gallon) and 340 

grams/liter (2.8 pounds/gallon), respectively. Both limits are expressed weight of 

VOC/volume of coating, less water and less exempt compounds, as applied. The VOC 

limits for specialty coatings ranging from 360 grams/liter (3.0 pounds/gallon) to 880 

grams/liter (7.3 pounds/gallon) depending on the category of coating. Specialty coating 

category includes camouflage, extreme performance, heat resistant, high gloss, high 

performance architectural, high temperature, metallic topcoat, pretreatment primer, 

silicone release, solar absorbent, and solid film lubricant. It is important to mention that if 

a certain coating type is not included under any of the listed specialty coating category, 

then the VOC limit for such coating is defaulted to the general coatings’ VOC limit (i.e., the 

general VOC limits for baked coating and for air-dried coating is 275 grams per liter (2.3 

pounds/gallon) and 340 grams/liter (2.8 pounds/gallon), respectively. 

The VOC limits for coatings used on large appliances parts and products, and metal 

furniture coating operations range from 275 grams/liter (2.3 lb/gal) to 420 grams/liter (3.5 

lb/gallon) depending on the type of coating applied and whether it is air-dried or baked. 

The coating types for large appliances parts and products, and metal furniture coating 

specified in the rule includes general one component, general, multi-component, extreme 

performance, heat resistant, metallic, pretreatment coating, and solar absorbent. As 

mentioned above, if a certain coating type is not included under any of the listed coating 

category for large appliances and metal furniture coating category, then the VOC limit for 

such coating is defaulted to the general coatings’ VOC limit (i.e., the general VOC limits 

for baked coating and for air-dried coating is 275 grams per liter (2.3 pounds/gallon) and 

340 grams/liter (2.8 pounds/gallon), respectively. 

In lieu of complying with the applicable coating VOC limits, an operator may use an 

APCO-approved VOC emission control system provided it is under District permit, has an 

overall capture and control efficiency of at least 90 percent by weight, and the emissions 

resulting from the use of the control system would not result in emissions in excess of 

those that would have been achieved had the operator complied with the VOC content 

limits of the coating or solvents. In addition to the coatings VOC limits, the rule also 

include provisions for coating application methods, which include electrostatic application, 

electrodeposition, high-volume, low-pressure (HVLP) spray equipment, flow coating, roll 

coating dip coating, brush coating or other application method demonstrated to the District 

as capable of achieving at least 65 percent transfer efficiency. 
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Rule 4603 establishes work practice standards only for large appliances parts and 

products, and metal furniture coating operations pursuant to EPA CTGs for such source 

categories. The current rule’s work practice standards for coating operations only apply to 

large appliances and metal furniture coating operations but not to other metal parts and 

products coating operations. The rule also includes organic solvent cleaning 

requirements. The current VOC content limits for organic solvent cleaning materials is 25 

grams/liter (0.21 pound/gallon) for all types of cleaning operations. Also, the rule includes 

administrative requirements such as coating product labeling, recordkeeping, and test 

methods to demonstrate compliance with the emission standards of the rule. 

B. Existing Rule 4684 (Polyester Resin Operations) 

Rule 4684 was adopted on May 19, 1994. The rule has undergone two amendments with 

the last occurring on September 20, 2007. The September 2007 rule amendments 

implemented the Best Available Retrofit Control Technology (BARCT) standards for 

organic solvent cleaning operations, pursuant to the California Health and Safety Code. 

The purpose of the rule is to limit VOC emissions from polyester resin operations and from 

organic solvent cleaning, storage and disposal of solvents and waste solvent materials 

associated with such operations. The rule applies to commercial and industrial polyester 

resin operations. Polyester resin operations is defined in the rule as methods used for the 

production or rework of products by mixing, pouring, hand layup, impregnating, injecting, 

forming, winding, spraying, and/or curing with fiberglass, filers, or other reinforcement 

materials and associated cleanup. 

Rule 4684 exempts facilities that use less than 20 gallons per month of polyester resin, 

provided the operator keeps the records required by the rule to demonstrate exemption 

status. Also exempt from the organic cleaning requirements of the rule are cleaning of 

solar cells, laser hardware, scientific instruments, or high precision optics. Cleaning in 

laboratory tests and analyses, or bench scale or research and development projects is 

also exempt from the organic cleaning requirements of the rule. 

Rule 4684 allows an operator to choose one of three compliance methods. One option is 

to use low-VOC polyester resins ranging from 35% to 50% by weight monomer content 

depending on the type of resin or gel coat. The second option is to use resins containing 

vapor suppressant wherein the weight loss from VOC emissions does not exceed 60 

grams per square meter of exposed surface during resin polymerization. The third option 

is to operate an APCO-approved VOC emission control system that achieves an overall 

capture and control efficiency of at least 85 percent by weight. 

Rule 4684 requires that spray application of resins be performed using airless, airassisted airless, high-volume low-pressure spray equipment, or electrostatic spray 

equipment. In lieu of using the specified spray equipment, the operator may comply by 

operating an APCO-approved VOC emission control system around the application 
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operation, provided the control system achieves an overall capture and control efficiency 

of at least 85 percent by weight. 

Rule 4684 requires operators to use organic solvent cleaning materials that contain no 

more than 25 grams/liter (0.21 pound/gallon) for all types of cleaning operations. Also, the 

rule includes administrative requirements such as recordkeeping and test methods to 

demonstrate compliance with the emission standards of the rule. 

 

For detailed requirements, please refer to the current Rules 4603 and 4684, which are 

available on the District’s website at www.valleyair.org. 

III. EPA CTG for Miscellaneous Metal and Plastic Parts (EPA-453/R-08-003, 

September 2008) 

In September 2008, EPA issued the CTG for miscellaneous metal and plastic parts 

coatings. The CTG applies to facilities where the total actual VOC emissions, including 

related cleaning activities, from all miscellaneous metal parts and products, miscellaneous 

plastic parts and products, and pleasure crafts at the facility are equal to or exceed 6.8 

kilograms per day (15 pounds per day), or an equivalent level of 2.7 tons per 12-month 

rolling period, before consideration of controls. The recommended threshold level is 

equivalent to the evaporation of approximately two gallons of solvent per day. EPA does 

not recommend the CTG standards apply to facilities that emit less than this level because 

of the very small reductions that can be achieved. 

CTG considers miscellaneous metal products and plastic products to include, but are not 

limited to, metal and plastic components of the following types of products as well as the 

products themselves: fabricated metal products, molded plastic parts, small and large 

farm machinery, commercial and industrial machinery and equipment, automotive and 

transportation equipment, interior or exterior automotive parts, construction equipment, 

motor vehicles, pleasure crafts (recreational boats), extruded aluminum structural 

components, railroad cars, heavier vehicles, lawn and garden equipment, business 

machines, laboratory and medical equipment, electronic equipment, steel drums, metal 

pipes, and numerous other industrial and household products. This CTG does not apply 

to other types of coating operations that are subject to other CTGs, such as fiberglass 

boat glass manufacturing for which a separate CTG was published by EPA in September 

2008. 

The CTG for miscellaneous metal and plastic parts and products includes VOC coating 

limits for miscellaneous metal parts and products, plastic parts and products, 

automotive/transportation and business machine plastic parts, pleasure crafts, and motor 

vehicles. 

The following discussions are excerpts from the provisions of the CTG: 

Process Description and Sources of VOC Emissions 
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Application of coatings on metal or plastic parts and products serve decorative, protective, 

and functional purposes. The coatings on the substrates of metal parts and products 

protect them from corrosion by providing resistance to moisture, heat, and outdoor 

elements. Coating plastic parts and products provides color, texture, or protection which 

improves appearance and durability, and can also function to attenuate electromagnetic 

interference/radio interference (EMI/RFI) signals, and to hide mold lines and flaws in the 

substrate surface. 

The three main process operations in the metal and plastic parts and products coating 

application process are surface preparation, coating application, and cleaning activities. 

All three operations use VOC-containing materials (coatings, thinners, and cleaning 

materials). Surface preparation is performed to correct any flaws in the part prior to 

coating, and to prepare the part to receive the coating. There are several different steps 

involve in the cleaning process of metal parts such as acid or alkaline cleaning, water 

rinse, phosphate treatment, water rinse, and pretreatment and/or water rinse, and finally 

drying the parts in an oven. For plastic parts or products, some sanding may be done to 

remove burrs or other inconsistencies besides puttying to fill any gaps or small cracks in 

the plastic part. For pre-primed plastic parts, spot primer may be applied to any areas 

missing primer or with an inconsistent primer application. After pretreatment, any 

remaining residue must be removed, typically, by wiping of the dust with water or alcohol 

soaked rugs. 

Coatings are applied using different methods such as conventional air spray, airless spray, 

air-assisted airless spray, electrostatic spray, high volume low pressure (HVLP), dip 

coating, flow coating, roll coating, electrocoating, autophoric coating, and zinc-arc spray. 

The CTG describes these different coating application methods. In a typical liquid spray 

and dip coating operations, the coated parts/products move from the coating application 

area through a flash-of area where solvents in the coating begin to evaporate slowly, thus 

avoiding bubbling of the coating while it is curing in the oven. After the typical coating 

operation, large appliance products are dried and cured using heated dryers or by air 

drying. Touch-up operations are performed using manual air spray guns and a lacquer 

base coating, which has good drying characteristics that allow for shorter drying times. 

VOC emissions from the coating processes occur from the evaporation of solvents in the 

coatings during coating application/flash-off and drying/curing of the coatings. About 65 to 

80 percent of the VOC from spraying liquid coatings are emitted during the application and 

flash-off operations, and 20 to 35 percent are emitted from the crying/curing operation. 

The remaining portion of the emissions is primarily from mixing or thinning operations. 

Available Controls for VOC Emissions from Coatings 

Two general types of emission control techniques for reducing VOC emissions from large 

appliance coatings are pollution prevention measures and emission capture and add-on 

control systems. Pollution prevention measures include coating product 
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substitution/reformulation, work practices, and equipment substitution. Low VOC content 

coatings (alternative coating formulations) include powder coatings, waterborne coatings, 

higher solids coatings, and ultraviolet (UV) curable liquid coatings and UV curable powder 

coatings. Work practice standards include storing VOC-containing materials and coatingrelated waste materials in closed containers, making sure that mixing and storage 

containers are kept close at all times as much as possible, minimizing spills, and 

conveying materials in closed containers or pipes. In addition to pollution prevention 

measures, emissions can be reduced by the use of capture system in conjunction with 

add-on control systems (e.g., thermal or catalytic oxidizer, adsorption, or absorption) that 

either destroy or recover VOCs in the exhaust streams. 

Emission Limits Based on Low-VOC Coatings 

The CTG include suggested limits for a variety of coatings. The following sections detail 

those limits for the four major categories: 

1. Metal Parts and Products Coatings 

The CTG recommends the VOC limits for metal parts and products coatings as shown in 

Table 1. These limits would be added to Rule 4603 as appropriate. 

Table 1 Metal Parts and Products VOC Content Limits

VOC Limit 

Air-dried baked 

Coating Type 

kg/l coating lb/gal 

coating 

kg/l coating lb/gal coating

General, one component 0.34 2.8 0.28 2.3 

General, multi-component 0.34 2.8 0.28 2.3 

Camouflage 0.42 3.5 0.42 3.5 

Electric-insulating varnish 0.42 3.5 0.42 3.5 

Etching filler 0.42 3.5 0.42 3.5 

Extreme high Gloss 0.42 3.5 0.36 3.0 

Extreme performance 0.42 3.5 0.36 3.0 

Heat resistant 0.42 3.5 0.36 3.0 

High performance 

architectural 

0.74 6.2 0.74 6.2 

High temperature 0.42 3.5 0.42 3.5 

Metallic 0.42 3.5 0.42 3.5 

Military specification 0.34 2.8 0.28 2.3 

Mold seal 0.42 3.5 0.42 3.5 

Pan backing 0.42 3.5 0.42 3.5 

Pre-fabricated architectural 

multi-component 

0.42 3.5 0.28 2.3 
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Table 1 Metal Parts and Products VOC Content Limits (continued) 

VOC Limit 

Air-dried baked 

Coating Type 

kg/l coating lb/gal 

coating 

kg/l coating lb/gal coating

Pre-fabricated architectural 

one-component 

0.42 3.5 0.28 2.3 

Pretreatment coatings 0.42 3.5 0.42 3.5 

Repair and touch up 0.42 3.5 0.36 3.0 

Silicon release 0.42 3.5 0.42 3.5 

Solar-absorbent 0.42 3.5 0.36 3.0 

Vacuum-metalizing 0.42 3.5 0.42 3.5 

Drum coating, new, exterior 0.34 2.8 0.34 2.8 

Drum coating, new, interior 0.42 3.5 0.42 3.5 

Drum coating, 

reconditioned, exterior 

0.42 3.5 0.42 3.5 

Drum coating, 

reconditioned, interior 

0.50 4.2 0.50 4.2 

2. Plastic Parts and Products Coatings 

Current Rule 4603 only applies to metal parts and products, large appliances parts and 

products, and metal furniture coating operations. Rather than developing a separate rule 

to implement the CTG for plastic parts and products coating operations and pleasure craft 

coating operations, District staff is proposing to revise the existing applicability of the rule 

so it would also apply to plastic parts and products coating operations and pleasure craft 

coating operations. The CTG recommends the VOC limits for plastic parts and products 

shown in Table 2. These limits would be added to Rule 4603 as appropriate. 

Table 2 Plastic Parts and Products VOC Content Limits 

Coating Type Kg VOC/liter coating Lb VOC/gal coating 

General one component 0.28 2.3 

General multi-component 0.42 3.5 

Electric dissipating coatings 

and shock-free coatings 

0.80 6.7 

Extreme performance 0.42 (2 pack coatings) 3.5 (2 pack coatings) 

Metallic 0.42 3.5 

Military specification 0.34 (1 pack) 

0.42 (2 pack) 

2.8 (1 pack) 

3.5 (2 pack) 

Mod-seal 0.76 6.3 

Multi-colored coatings 0.68 5.7 

Optical coatings 0.80 6.7 

Vacuum-metalizing 0.80 6.7 
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For plastic parts and products coating operations (except for automotive/transportation 

and business machine plastic parts and products), the CTG recommended that the 

coating operations listed below would not need to comply with the applicable coating VOC 

limits for plastic parts and products coating operations, but they would be subject to the 

work practice standards. 

• Touch up and repair. 

• Stencil coatings applied on clear or transparent substrate. 

• Clear or translucent coatings. 

• Coatings applied at a paint manufacturing facility while conducting performance 

tests on coatings. 

• Any individual coating category used in volumes less than 50 gallons in any one 

calendar year, if substitute compliance coatings are not available, provided the total 

usage of all such coatings does not exceed 200 gallons per calendar year, per 

stationary source. 

• Reflective coatings used on highway cones. 

• Mask coatings that are less than 0.5 millimeter thick (dried) and area coated is less 

than 25 square inches. 

• Electromagnetic interference/radio frequency interference shielding coatings 

• Mask coatings that are less than 0.5 millimeter thick (dried) and the area coated is 

less than 25 square inches. 

• Heparin-bezalkonium chloride (HBAC)-containing coatings applied to medical 

devices, provided the total usage of all such coatings does not exceed 100 gallons 

per year per facility. 

Furthermore, for plastic parts and products coating operations (except for 

automotive/transportation and business machine plastic parts and products, the coating 

application methods would not apply to airbrush coating application operation using 5 

gallons or less of coating per calendar year, provided the operator keeps the records 

required by the rule to demonstrate that the coating usage is below the allowable 

exemption amount. 

3. Automotive/Transportation and Business Machine Plastic Parts and Products 

Coating 

The CTG recommended the VOC limits shown in Table 3. These limits would be added to 

Rule 4603 as appropriate. 
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Table 3 - VOC Content Limits for Automotive/Transportation and Business Machine Plastic Parts 

and Products Coating Operations

Automotive/Transportation Plastic Parts and Products Coatings 

Coating Type VOC Limit in kg/liter (lb/gallon) 

I. High Baked Coatings – Interior and Exterior 

Flexible Primer 0.54 (4.5) 

Non-flexible Primer 0.42 (3.5) 

Basecoat 0.52 (4.3) 

Clearcoat 0.48 (4.0) 

Non-basecoat/clearcoat 0.52 (4.3) 

II. Low Bake/Air-Dried Coatings – Exterior Parts 

Primers 0.58 (4.8) 

Basecoat 0.60 (5.0) 

Clearcoat 0.54 (4.5) 

Non-basecoat/clearcoat 0.60 (5.0) 

III. Low Bake/Air-Dried Coatings – Interior parts 0.60 (5.0) 

IV. Touch-up and Repair Coatings 0.62 (5.2) 

Business Machine Plastic Parts and Products Coatings 

Coating Type VOC Limit in kg/liter (lb/gallon) 

Primer 0.35 (2.9) 

Topcoat 0.35 (2.9) 

Texture Coat 0.35 (2.9) 

Fog Coat 0.26 (2.2) 

Touch-up and Repair 0.35 (2.9) 

4. Pleasure Craft Coating 

The CTG recommends the VOC limits for pleasure craft surface coating shown in Table 4. 

These limits would be added to Rule 4603 as appropriate. 

Table 4 Pleasure Craft Surface Coating VOC Content Limits 

Coating Type VOC limit in kg/liter coating VOC limit in lb/gal coating 

Extreme high gloss topcoat 0.49 4.1 

High gloss topcoat 0.42 3.5 

Pretreatment wash primers 0.78 6.5 

Finish primer/surfacer 0.42 3.5 

High build primer surface 0.34 2.8 

Aluminum substrate 

antifoulant coating 

0.56 4.7 

Other substrate antifoulant 

coating 

0.33 2.8 

All other pleasure craft 

surface coating for metal or 

plastic 

0.42 3.5 
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5. Motor Vehicle Materials 

The CTG included VOC limits for motor vehicle materials as shown in Table 5. These 

limits will not be included in Rule 4603, but they will be included in proposed amendments 

to Rule 4602 (Motor Vehicle Assembly Coatings) currently underway in order to implement 

the CTG for Automobile and Light-Duty Truck Assembly Coatings promulgated by EPA in 

September 2008. 

Table 5 Motor Vehicle Materials VOC Content Limits 

Motor Vehicle Material VOC limit in kg/liter coating VOC limit in lb/gal coating 

Cavite wax 0.65 5.4 

Sealer 0.65 5.4 

Deadener 0.65 5.4 

Gasket/gasket sealing 

material 

0.20 1.7 

Underbody coating 0.65 5.4 

Trunk interior coating 0.65 5.4 

Bedliner 0.20 1.7 

Lubricating wax/compound 0.70 5.8 

Add-on Control system 

If product performance or other needs dictate the use of higher VOC materials than those 

that would meet the recommended VOC limits in Tables 1 through 4, a facility could 

choose to use add-on control equipment with an overall control efficiency of 90 percent in 

lieu of using low-VOC coatings and specified application methods. This control option 

applies to all coatings and thinners applied to miscellaneous metal and plastic 

components or products, except for motor vehicles. But as noted above, the VOC limits 

for motor vehicles materials would not be included in Rule 4603, but they would be 

included in a separate rulemaking project to amend Rule 4602 (Motor Vehicle Assembly 

Coatings). 

Proposed Amendments to Rule 4603 

The District’s permit database indicates that there approximately 300 permitted sources 

that are subject to Rule 4603. Staff reviewed the reports of inspections conducted by the 

District’s Compliance Division and determined that operators are already using coatings 

that comply with the draft amendments to Rule 4603.

Comparison of Rule 4603 Coating VOC Limits with CTG Standards 

Rule 4603 general coating limits are: Air-dried is 275 grams per liter (2.3 pounds per 

gallon) of coating, less water and exempt compounds, as applied. Baked is 340 grams 
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per liter (2.8 pounds per gallon) of coating, less water and exempt compounds, as applied. 

The specialty coating VOC limits for baked range from 880 grams per liter (7.3 pounds per 

gallon) to 360 grams per liter (3.0 pounds per gallon) of coating, less water and exempt 

compound, as applied, depending on the type of specialty coating; and for air-dried the 

limits range from 880 grams per liter (7.3 pounds per gallon) to 420 grams per liter (3.5 

pounds per gallon) of coating less water and exempt compound, as applied, depending on 

the type of specialty coating. Coatings that are not specified in the table of VOC limits for 

specialty coatings are defaulted to the general coating category as specified above. 

Rule 4603 does not include all the metal parts and products coating categories listed in 

the CTG. Those coating categories included in the CTG are considered by District staff as 

being regulated under the general coating limits specified in Rule 4603. Some of the 

CTG coating VOC limits for miscellaneous metal parts and products (except for coatings 

used for large appliances and metal furniture coating operations) are less stringent than 

Rule 4603 existing general coating limits (baked: 2.8 pounds per gallon; air-dried: 2.3 

pounds per gallon) for the following CTG coating categories: 

• Electric-insulating varnish: 3.5 pounds per gallon (baked or air dried) 

• Etching filler: 3.5 pounds per gallon (baked and air dried) 

• Mold seal: 3.5 pounds per gallon (baked or air dried) 

• Pan backing: 3.5 pounds per gallon (baked or air dried) 

• Prefabricated architectural multi-component: 3.5 pounds per gallon (air-dried) 

• Prefabricated architectural one-component: 3.5 pounds per gallon (air-dried) 

• Pretreatment coating: 3.5 pounds per gallon (baked and air dried) 

• Vacuum-metalizing: 3.5 pounds per gallon (baked or air-dried) 

In addition, the CTG limits for baked camouflage coating and for metallic coating of 3.5 

pounds per gallon is less stringent than Rule 4603 limit of 3.0 pounds per gallon. The 

CTG limit for baked extreme performance coating of 3.0 pounds per gallon is slightly more 

stringent than Rule 4603 limit of 3.5 pounds per gallon. Repair and touch-up coating is 

exempt in Rule 4603, but the CTG’s repair and touch repair coating VOC limit is 3.5 

pounds per gallon (air-dried) and 3.0 pounds per gallon (baked). 

As discussed above, for metal parts and products CTG coating VOC limits, District staff is 

proposing only to incorporate the VOC limit for extreme performance coating because it is 

more stringent than the existing rule 4603, remove the current rule’s exemption for touch 

and repair and also specify the CTG limit of 3.5 lb/gal for air dried and 3.0 lb/gal for baked. 

Other coating categories in the CTG which have less stringent VOC limits than Rule 4603 

general coating limits, as discussed above, would not be incorporated because it would be 
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a relaxation of the current SIP-approved rule which EPA does allow. Likewise, the CTG 

recommends to not apply the VOC limits for the stencil coatings; safety-indicating 

coatings; solid-film lubricants; electric-insulating and thermal-conducting coatings, 

magnetic data storage disk; and plastic extruded onto metal parts to form a coating. 

These exemptions would not be incorporated into the rule because it would constitute a 

relaxation of the SIP-approved version of the rule since Rule 4603 currently does not 

currently exempt such coating operations. 

The CTG’s VOC limits for drum coating categories would not be included in Rule 4603 

since drum manufacturing is subject to Rule 4603 (Can and Coil Coating Operations). 

The CTG limit for reconditioned drum interior coating of 4.2 lb/gal (504 grams/liter) is 

slightly more stringent that Rule 4604 limit of 510 grams/liter. However, since there is no 

reconditioned drum coating operation currently operating within the District, staff would not 

recommend amending Rule 4604. Any reconditioned drum coating operation that may 

operate in the future within the District would be subject to Rule 2201 (New and Modified 

Stationary Source Rule) requirements for Best Available Control technology (BACT) and 

emission offset requirements. Therefore, it is not necessary to amend Rule 4604 at this 

time. 

The following are proposed amendments to Rule 4603 to implement the CTG for 

miscellaneous metal parts and products coatings. The proposed amendments would be 

effective on and after January 1, 2011. 

• The title of the rule would be changed to read: Surface Coating of Miscellaneous Metal 

Parts and Products, Plastic Parts and Products, and Pleasure Crafts. 

• Section 1.0 (Purpose) would be changed to include limiting the VOC emissions from 

plastic parts and products, automotive/transportation and business machine plastic 

parts and products, and pleasure craft coating operations. 

• Section 2.0 (Applicability) would be changed so the rule also applies to plastic parts 

and products, automotive/transportation and business machine plastic parts and 

products, and pleasure craft coating operations. 

• Section 3.0 (Definitions) would be include 25 new definitions and modify some existing 

definitions to enhance clarity and effectiveness of the rule. 

• Section 4.0 (Exemption) would be modified so that the existing exemption for touch-up 

and repair would be removed effective on and after (one day before rule amendments 

adoption date) and a VOC content limit of 360 grams/liter (3.0 lb/gallons) for baked and 

420 grams/liter (3.5 lb/gallon) for air-dried would be specified to make it consistent with 

the CTG. 
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• Section 5.0 (Requirements) would include changes to the existing table of VOC limits 

for metal parts and products coating operations, add separate tables of VOC coating 

limits for plastic parts and products, for automotive/transportation and business 

machine plastic parts and products, and for pleasure craft. 

• The work practice standards recommended by the CTG would be incorporated into 

Rule 4603. The standards include: storing all VOC-containing coatings, thinners, and 

cleaning materials, and waste materials in closed non-absorbent and non-leaking

containers, and such containers should remain closed at all times, except when 

specifically in use; closing the mixing vessels that contain VOC coatings and other 

materials, except when specifically in use; minimizing spills of any VOC-containing 

materials and clean up spills immediately; and conveying VOC-containing materials in 

closed containers or pipes. Although the CTG only recommends work practice 

standards, but no specific VOC limit for organic cleaning solvents, the sources in the 

District covered by the CTG would still be required to comply with the existing cleaning 

solvent VOC limit of 25 grams/liter in order to prevent relaxation of the SIP-approved 

rule. 

• Existing Section 6.5 would be deleted because it serves no useful purpose since the 

year of revision of ASTM test method is already specified in the rule itself. EPA has 

historically wanted the District to specify the revision year of the ASTM test method 

instead of stating “the most recent version of such test method”.

For Miscellaneous Metal Parts and Products Coatings

• The existing VOC content limit for Extreme Performance Coating would be lowered 

from 420 grams/liter (3.5 lb/gallon) to 360 grams/liter (3.0 lb/gallon) to make it 

consistent with the CTG. 

• The current exemption for touchup and repair coating would be remove and new VOC 

limits would be 360 grams/liter (3.0 lb/gallon) for baked and 420 grams/liter (3.5 

lb/gallon) for air-dried 

Plastic Parts and Products Coating Operations (Except for Automotive/Transportation and 

Business Machine Plastic Parts and Products) 

District staff reviewed the District Permit database and determined that there are only two 

permitted facilities that perform surface coating of plastic parts and products1, but each 

facility’s total VOC emissions from coating and cleaning operations, before consideration 

of controls, are below the CTG applicability threshold of 15 lb VOC/day or 2.7 tons VOC 

 

1

 Fairmont Sign Company (PTO: N-4223-1): Permit VOC limit for plastic coating operation is 2 lb/day. 

Premier Coatings-DBA Premier Finishing (PTO: N-4338-12-1): Permit VOC limit for plastic coating 

operation is 3,195 lb/year (1.59 tons/year). 
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per 12-month rolling period from all metal parts and products, automotive/transportation 

and business machine plastic parts and products, and pleasure craft coating operations, 

including related cleaning operations, before consideration of controls, at a stationary 

source. Although no existing sources would be subject to the draft coating VOC limits, 

District staff would include the CTG limits into the rule as a “back-stop” in the event new or 

modified sources become subject to the coating limits in the future. 

The following are proposed amendments to Rule 4603 to implement the CTG for plastic 

parts and products coatings: 

• The rule would include the CTG VOC content limits ranging from 275 grams/liter (2.3 

lb/gallon) to 804 grams/liter (6.7 lb/gallon), depending on the type of coating (i.e., 

general one component coating, general multi-component coating, extreme 

performance coating, metallic coating, multi-colored coating, etc.). The VOC limits 

would only apply to operators whose total VOC emissions from all metal parts and 

products, automotive/transportation and business machine plastic parts and products, 

and pleasure craft coating operations, including related cleaning operations, before 

consideration of controls, at a stationary source are equal to or greater than 2.7 tons of 

VOC per 12-month rolling period. Operators of plastic parts and products coating 

operations whose total VOC emissions at a stationary source are below the 2.7 tons of 

VOC per 12-month rolling period threshold are not required to comply with the 

applicable coatings VOC limits. However, the operator would need to comply with the 

applicable recordkeeping requirements of the rule and also calculate the VOC emission 

to demonstrate if the VOC emissions are below the specified threshold. 

• As recommended by the CTG, the exemption in Section 4.0 would include a provision 

that the coatings VOC limits in Table 3 and the solvent cleaning requirements would 

not apply to the coatings and coating operations listed below provided the operator 

complies with the work practice standards and coating application methods specified in 

the rule. 

• Touch-up and repair coatings; 

• Stencil coatings applied on clear or transparent substrate; 

• Clear or translucent coatings; 

• Coatings applied at a paint manufacturing facility while conducting performance 

tests on coatings; 

• Individual coating category used in volumes less than 50 gallons in any one 

calendar year, if substitute compliance coatings are not available, provided the 

total usage of all such coatings does not exceed 200 gallons per calendar year, 

per stationary source; 

• Reflective coatings used on highways; 

• Mask coatings that are less than 0.5 mm thick (dried) and the area coated is less 

than 25 square inches; 
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16 Final Staff Report with Appendices for Amendments 

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• Electro-magnetic interference (EMI) and radio frequency interference (RFI) 

shielding coatings; 

• Heparin-bezalkonium chloride (HBAC)- containing coatings applied on medical 

devices, provided the total usage of all such coatings does not exceed 100 gallons 

per calendar year, per stationary source; and 

• The coating application methods would not apply to airbrush operations using five 

(5) gallons or less of coating per calendar year provided the operator complies 

with the applicable VOC limits, work practice standards, and recordkeeping 

requirement in the rule. 

• As recommended by EPA, Section 4.7 would be clarified that the exemption for 

polyester resin operations and the application of polyester resin materials on metal 

parts and products would be clarified by specifying that such operations are subject to 

Rule 4684 (Polyester Resin Operations). 

• As discussed above, the work practice standards recommended by the CTG would be 

included in the rule and would apply to plastic parts and products coating operations. 

Automotive/Transportation and Business Machine Plastic Parts and Products Coating 

Operations 

District staff reviewed the District Permit database and determined that there are no 

facilities that perform automotive/transportation and business machine plastic parts and 

products coating operations. Although no sources would be subject to the new coating 

VOC limits, District staff would include the CTG limits into the rule as a “back-stop” in the 

event new or modified sources become subject to the coating limits in the future. 

The following are proposed amendments to Rule 4603 to implement the CTG for 

automotive/transportation and business machine plastic parts and products coatings: 

• The rule would include coating VOC content limits ranging from 348 grams/liter (2.9 

lb/gallon) to 600 grams/liter (5.0 lb/gallon), depending on the type of coating (e.g., 

general one component coating, general multi-component coating, extreme 

performance coating, metallic coating, multi-colored coating, etc.). 

• As recommended by the CTG, the coating VOC limits would only apply to operators 

whose total VOC emissions from all metal parts and products, 

automotive/transportation and business machine plastic parts and products, and 

pleasure craft coating operations, including related cleaning activities, before 

consideration of controls, at a stationary source are equal to or greater than 2.7 tons of 

VOC per 12-month rolling period. Operators of automotive/transportation and business 

machine plastic parts and products coating operations whose total VOC emissions at a 

stationary source are below the 2.7 tons of VOC per 12-month rolling period threshold 

are not required to comply with the applicable coatings VOC limits. However, the 
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17 Final Staff Report with Appendices for Amendments 

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operator shall comply with the applicable recordkeeping requirements of the rule and 

calculate the VOC emission to demonstrate if the VOC emissions are below the specified 

threshold. 

• As recommended by the CTG, the exemption in Section 4.0 would include a provision 

that the coatings VOC limits and the solvent cleaning requirements would not apply to 

the coatings and coating operations listed below provided the operator complies with 

the work practice standards and coating application methods specified in the rule. 

• Texture coatings; 

• Vacuum metalizing coatings; 

• Gloss reducers; 

• Texture topcoats; 

• Adhesion primers; 

• Resist coatings; and 

• Stencil coatings. 

• As discussed above, the work practice standards recommended by the CTG would be 

included in the rule and would also apply to automotive/transportation and business 

machine plastic parts and products coating operations. 

Pleasure Craft Coating Operations 

District staff reviewed the District Permit database and determined that there are seven 

permitted facilities that maybe performing surface coating of pleasure crafts2

 and could be 

subject to the new coating VOC limits being included into the rule. 

The following are proposed amendments to Rule 4603 to implement the CTG for pleasure 

craft coatings: 

• The rule would include coatings VOC content limits ranging from 336 grams/liter (2.8 

lb/gallon) to 780 grams/liter (6.5 lb/gallon), depending on the type of coating (e.g., 

extreme high gloss, high gloss, pretreatment wash primer, high build primer surfacer, 

aluminum substrate antifoulant coating, etc.). 

• As recommended by the CTG, the coatings VOC content limits would only apply to 

pleasure craft coating operations whose total actual VOC emissions from all metal 

parts and products, automotive/transportation and business machine plastic parts and 

products, and pleasure craft coating operations, including related cleaning activities, 

before consideration of controls, at a stationary source are equal to or greater than 2.7 

 

2 International Inboard Marine (PTO: N-3296); Marine Services (PTO: N-3905); Malibu Boats LLC (PTO: N3941); Fineline Industries, Inc. (PTO: N-1246-1-1); Wakecraft Boats Inc. (PTO: N-7450-1-0); Belmont Boats 

(PTO: C-110-1-0); Sanger Boats, Inc. (C-1074-1-4); 
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tons of VOC per 12-month rolling period. Operators of pleasure craft coating 

operations whose total VOC emissions at a stationary source below the 2.7 tons of 

VOC per 12-month rolling period threshold are not required to comply with the 

applicable coatings VOC limits. However, the operator shall comply with the applicable 

recordkeeping requirements of the rule and calculate the VOC emission to demonstrate 

if the VOC emissions are below the specified threshold. 

• As recommended by the CTG, the coating application methods would not apply to 

extreme gloss coatings and the solvent cleaning requirements provided the operator 

complies with the VOC limit for such coating category and the work practice standards 

of this rule. 

• As recommended by EPA, existing Section 5.7.6 pertaining to alternative compliance 

option which allows an operator to operate an APCO approved VOC emission control 

system in lieu of complying with the specified cleaning solvent VOC limit would be 

deleted because this section is duplicative of the identical provision in existing Section 

5.10.2 that allows an alternative compliance option. 

• The application equipment requirements in Section 5.12 would be modified to specify 

that the required coating application methods apply to metal parts and products, large 

appliances parts and products, metal furniture, plastic parts and products, 

automotive/transportation and business machine parts and products, and pleasure 

crafts. 

• As discussed above, the work practice standards recommended by the CTG would be 

included in the rule and would also apply to pleasure craft coating operations. 

IV. CTG for Fiberglass Boat Manufacturing Materials (EPA-453/R-08-004, 

September 2008) 

In September 2008, EPA issued a CTG for fiberglass boat manufacturing which provides 

recommendations for controlling VOC emissions from the use of gel coats, resins, and 

materials used to clean application equipment. The CTG applies to facilities that 

manufactures hulls or decks of boats from fiberglass, or build molds to make fiberglass 

hulls or decks. The CTG does not apply to facilities that manufacture solely parts of boats 

(such as hatches, seats, or lockers) or boat trailers, but do not manufacture decks or hulls 

of boats from fiberglass, or build molds to make hulls or decks. However, if a facility 

manufactures hulls or decks and also manufactures all other fiberglass boat parts (such 

as hatches, seats, lockers) then the facility is subject to the CTG standards. 

The CTG apply to fiberglass boat manufacturing facilities where the total actual VOC 

emissions from all fiberglass boat manufacturing operations including cleaning operations, 

before consideration of controls, are equal to or exceed 15 lb/day or an equivalent 

threshold of 2.7 tons per 12-month rolling period. The CTG does not recommend the 
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control requirements apply to facilities below the stated threshold because of very small 

VOC emission reductions that could be achieved since such a level is considered to be 

very low within the fiberglass boat manufacturing industry and is expected only from 

facilities producing only small number of small boats. The CTG does not extend to 

surface coatings applied to fiberglass boats and does not apply to industrial adhesives 

used in the assembly of fiberglass boats. Surface coating of fiberglass and metal 

recreational boats (pleasure craft) and covered by the CTG for miscellaneous metal and 

plastic parts and products which is being incorporated into the draft amendments to Rule 

4603 as discussed above. Polyester resin putties that are used in assembling fiberglass 

parts are not considered adhesives so they are subject to the fiberglass boat 

manufacturing CTG standards. 

A. Process Description and Sources of VOC Emissions 

The CTG includes a detailed discussion of the processes involve in manufacturing 

fiberglass boat hulls or decks and miscellaneous small fiberglass parts such as tanks, 

seats, lockers, and hatches. Fiberglass boats are typically manufactured in a process 

called open molding. Separate molds are used for boat hull, deck, and miscellaneous 

small parts. Resins and gel coats are used to manufacture fiberglass boat hulls or decks 

and miscellaneous small parts. 

The primary VOC emitted from fiberglass boat manufacturing materials are styrene and 

methacrylate. The resin contains styrene and the gel coat contains both compounds. 

Styrene and methacrylate are both monomers. A fraction of the monomer evaporates 

during resin and gel coat application and curing. The majority of the monomer is bound in 

the cross-linking reaction between the polymer molecules in the hardened resin or gel coat 

which become part of the finished product, so not all of the styrene or methacrylate 

evaporate during the boat manufacturing process. The amount of monomer VOC emitted 

is dependent on several factors, including initial monomer content, application method, 

and thickness of the part or the layer that is curing. The VOC emission is usually 

expressed in terms of lb monomer per ton of material applied, or kg per megagram. 

B. Available Control Options for Resins and Gel Coat 

1. Low Monomer Resins and Gel Coats 

Reducing the monomer content of the resin or gel coat and using non-atomized 

application method reduces the monomer VOC emissions from resins and gel coats used 

in open molding at fiberglass boat manufacturing process. The CTG discussed how 

different resins and gel coats can be reformulated to achieve varying levels of lowered 

monomer VOC contents depending on their use in the manufacturing process. From a 

regulatory standpoint, low-monomer VOC content requirement is easier to monitor and 

enforce and also easier for facility operators to demonstrate compliance on a continuous 
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basis compared to other control options such as installing and operating a VOC control 

system. 

As discussed in South Coast Air Quality Management District‘s Final Staff Report for Rule 

1162 dated November 2001, Ultra Violet (UV) curing and Electron Beam (EB) resins are 

considered near zero or zero emission resins because of their instantaneous 

polymerization. SCAQMD staff’s research in 2001 indicates that EB and UV curing 

technology for composite industry is a promising technology for certain applications. 

2. Vapor Suppressed Resin and Gel Coats 

Vapor suppressed resins and gel coats may be used to achieve emissions reductions 

without changes in equipment. Vapor suppressed resin or gel coat have an additive, 

typically a wax, to reduce evaporation of monomer VOC by forming a film on the resin or 

gel coat surface as it cures. But the vapor suppressing wax presents significant technical 

problems in boat manufacturing. Boats are relatively large and complex so they are 

usually built and assembled from subassemblies that eventually must be bonded together. 

To achieve a good secondary bond between two parts made of vapor suppressed resins, 

the wax film on the bonding surfaces must be removed by grinding or sanding before the 

pars can be bonded. This additional surface preparation can be labor intensive such that 

one boat manufacturer estimated that switching to vapor suppressed resins caused about 

a 25% labor increase in building parts. Also, the ultimate strength of the bonded parts 

may also be reduced such that the possibility of structural failure may also increase. 

3. Non-atomizing Resin Application 

The CTG indicated that switching from atomizing to non-atomizing application of resin with 

a 35% styrene achieves a 41% emissions reduction. If both styrene content and 

application method are changed, the emission reduction can be greater that changing the 

percent styrene content alone or the application method only. The CTG stated that 

changing from an atomized application method with a resin of 40% styrene content to 35% 

styrene content that is applied with non-atomizing technology can achieve a 58% emission 

reduction. 

The CTG includes a detailed discussion on non-atomizing resin application techniques, 

which include bucket and brush application by hand, resin rollers, resin impregnators, and 

fluid impingement technology. All these methods reduce emissions by eliminating the 

atomization of resins. Non-atomizing technology is feasible for applying production and 

tooling resins only. Gel coats must still be applied with atomizing spray guns, so reduction 

from gel coats can only be achieved by using low monomer VOC gel coats. An exception 

is gel coat that can be applied with a brush or roller to the interior areas of finished boats 

where cosmetic appearance is not as critical as the exterior. 
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4. Closed Molding 

Closed molding is a fabrication technique in which reinforced plastic parts are produced 

between the halves of a two-part mold, or between a mold and a flexible membrane, such 

as a bag. The four types of closed molding methods used in fiberglass boat 

manufacturing, as described in detail by the CTG, include vacuum bagging, vacuumassisted resin transfer molding, resin transfer molding, and compression molding with 

sheet molding compound. Closed molding processes as currently practiced cannot be 

used to reduce emissions during gel coat or skin coat application because these 

applications must still use conventional open molding techniques reduce. But closed 

molding can still be used to reduce monomer VOC emissions from subsequent laminating 

steps after the gel coat and skin coat layers have been applied. 

The CTG has indicated that one fiberglass boat manufacturer in the nation has developed 

a patented closed molding process that has replaced open molding for hulls of many of its 

smaller (17 to 22 feet long) power boats. However, closed molding is generally applicable 

to making large number of small parts, such as hatches, doors, or small number of high 

performance boat hulls and decks, but it is not feasible to replace open molding with 

closed molding at all types of boat manufacturing facilities 

C. Proposed Amendments to Rule 4684 (Polyester Resin Operations) 

District staff reviewed the District Permit database and determined that there are seven 

fiberglass boat manufacturing facilities3

 that are currently subject to Rule 4684 and may be

be affected by the VOC limits being proposed for resins and gel coats. It is important to 

mention that some of the permitted boat manufacturing facilities in the District are major 

sources (sources that emit at least 10 tons per year of VOC or nitrogen oxides) so they will 

be issued federally-mandated Title V operating permits. Other boat manufacturing 

facilities in the District permitted VOC emissions are less than the CTG applicability 

threshold of 2.7 tons per 12-month rolling period so they will not be subject to the 

proposed amendments. In addition, those boat manufacturers in the District that are 

major sources of hazardous air pollutant (sources that emit at least 10 tons per year of a 

single of HAP or at least 25 tons per year of a combination of HAP) are already subject to 

the control requirements pursuant to 40 CFR Part 63 Subpart VVVV (National emission 

Standards for Hazardous Air Pollutants), which EPA promulgated in August 2001. The 

CTG control requirements for fiberglass boat manufacturing materials are consistent with 

40 CFR Part 63 Subpart VVVV. 

The following are proposed amendments to Rule 4684. The proposed amendments 

would be effective on and after January 1, 2011. 

 

3 International Inboard Marine (PTO: N-3296); Marine Services (PTO: N-3905); Malibu Boats LLC (PTO: N3941); Fineline Industries, Inc. (PTO: N-1246-1-1); Wakecraft Boats Inc. (PTO: N-7450-1-0); Belmont Boats 

(PTO: C-110-1-0); Sanger Boats, Inc. (C-1074-1-4); 
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• Section 2.0 (Applicability) would be expanded to clarify that the rule also applies to 

fiberglass boat manufacturing operations. 

• Section 3.0 (Definitions) would include 17 new definitions of terms associated with 

fiberglass boat manufacturing in order to enhance the clarity and effectiveness of the 

rule. 

• Section 4.1 (Exemption) would be modified to state that the existing 20 gallon or less 

per month of polyester resin materials usage exemption does not apply to fiberglass 

boat manufacturing. The reason for excluding fiberglass boat manufacturing from this 

low-usage exemption is due to the CTG not having a similar exemption for fiberglass 

boat manufacturing. 

• As recommended by the CTG standards, a new Section 4.2 would be added to exempt 

production resins (including skin coats) that must meet the specifications for use in 

military vessels or must be approved by the U.S. Coast Guard for use in construction 

of lifeboats, rescue boats, and other life-saving appliances approved under 40 CFR 

subchapter Q, or to the construction of small passenger vessels regulated by 46 CFR 

subchapter T are exempt from the requirements of Section 5.2.2. This exemption does 

not constitute relaxation of the SIP-approved version of the rule because there are no 

boat manufacturing sources within the District is currently manufacturing vessels or 

pleasure crafts that meet the criteria stated above. The CTG recommended that the 

open molding and non-monomer VOC limits do not apply to production and tooling 

resins, and pigmented, clear and tooling gel coat used for part or mold repair and 

touch-up, as well as 100% vinylester resin, District staff is not incorporating the CTG’s 

recommendation to exempt such resins and gel coats because it would constitute 

relaxation of a SIP-approved version of Rule 4684 since existing permitted boat 

manufacturing facilities are able to comply with the monomer content limits of the 

existing rule. 

• Section 5.0 (Requirements). Section 5.1 would be modified to specify that the 

requirements apply to polyester resin operations, except for fiberglass boat 

manufacturing which would subject to new Section 5.2. New Section 5.2 would 

include three compliance options for controlling VOC emissions from fiberglass boat 

manufacturing. The new monomer VOC limits would apply only to fiberglass boat 

manufacturing facilities whose total VOC emissions from open molding fiberglass boat 

manufacturing operations, including related solvent cleaning activities, before 

consideration of controls, at a stationary source are equal to or greater than 2.7 tons of 

VOC per 12-month rolling period. The operator would need to comply with the 

applicable recordkeeping requirements of the rule and would have to calculate the 

VOC emissions to demonstrate that the VOC emissions are at least 2.7 tons per 12-

month rolling period. Operators of fiberglass boat manufacturing operations whose 

VOC emissions are less than specified VOC applicability threshold of 2.7 tons of VOC 
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23 Final Staff Report with Appendices for Amendments 

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per 12-month rolling period would be still be subject to the current resin and gel coat 

monomer content limit specified by the existing rule (please see discussion on page 24 

of this staff report). Please refer to the draft rule for details of the emission control 

requirements of the compliance options listed below. 

o Compliant Material Option: Achieve the specified individual monomer content 

limits. The weighted average monomer VOC content limits for fiberglass boat 

manufacturing open molding process ranging from 28% to 40% by weight 

depending on the type of resin (i.e., production resin and tooling resin), type of gel 

coat (pigmented gel coat, clear gel coat, and tooling gel coat), and also depending 

on the application method. The proposed monomer VOC content limits are shown 

in Table 6. In addition to complying with the monomer VOC content limit, each 

resin and each gel coat must not contain more than 5% by weight non-monomer 

VOC content. The rule would include the calculation equations to determine the 

weighted average monomer VOC content. 

 Table 6 Compliant Materials Monomer VOC Content for Open Molding Resin and Gel 

Coat 

 Material Application Method Weighted Average Monomer 

VOC content (weight percent) 

limit 

Production Resin Atomized (spray) 28% 

Production Resin Nonatomized 35% 

Pigmented Gel Coat Any method 33% 

Clear Gel Coat Any method 48% 

Tooling Resin Atomized 30% 

Tooling Resin Nonatomized 39% 

o Emissions Averaging Option: Meet the numerical monomer VOC emission rate 

limits as shown in Table 7, which would enable an operator to average emissions 

among different operations using the equations in the draft rule to estimate the 

monomer VOC emissions rates from each operation based on material and 

application method. In addition to complying with a facility-specific monomer VOC 

mass emission rate (12-month rolling average), each resin and gel coat must not 

contain more than 5% by weight non-monomer VOC content. A table of the 

Monomer VOC Emission Rate Formulas for Open Molding Operations would be 

included in Rule 4684. 
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Table 7 Monomer VOC Emission Rate Formulas for Open Molding 

Material Application Method Formula to calculate 

monomer VOC emission rate*

Atomized 0.014 x (Resin VOC%)2.425

Atomized, plus vacuum bagging with roll-out 0.01185 x (Resin VOC%)2.425

Atomized, plus vacuum bagging without rollout 0.009454 x (Resin 

VOC%)2.425

Nonatomized 0.014 x (Resin VOC%)2.275

Nonatomized, plus vacuum bagging with rollout 0.0110 x (Resin VOC%)2.275

Production 

resin, Tooling 

resin 

Nonatomized, plus vacuum bagging without 

roll-out 

0.0076 x (Resin VOC%)2.275

Pigmented gel 

coat, clear gel 

coat, tooling gel 

coat 

All methods 0.0045 x (Gel coat 

VOC%)1.675

 The formulas in Table 7 calculate monomer VOC emissions in kilograms of monomer per 

megagram of resin or gel coat applied. The formulas for vacuum bagging with roll-out are 

applicable when a facility rolls out the applied resin and fabric prior to applying the vacuum 

bagging materials. The formulas for vacuum bagging without roll-out are applicable when a facility 

applies the vacuum bagging materials immediately after resin application without rolling the resin 

and fabric. VOC% = monomer VOC content as supplied, expressed as a weight-percent value 

between 0 and 100%. 

o Add-on Control Option: Install and operate an APCO-approved VOC control 

system to achieve a numerical monomer VOC emission limit that is determined for 

each facility based on the mix of application methods and materials used at that 

facility. Additionally the VOC control system must also meet the existing 85% 

capture and control efficiency specified in the current rule. 

Requirements for Fiberglass Boat Manufacturing Operations with VOC Emissions Less 

than 2.7 tons per 12-month Rolling Period 

Operators of fiberglass boat manufacturing operations whose VOC emissions are less 

than 2.7 tons of VOC per 12-month rolling period or fiberglass boat manufacturing 

operations using a closed molding process would be still be subject to the current resin 

and gel coat monomer content limit specified by the existing rule. The existing rule VOC 

limits are: 35% monomer by weight for low VOC resins, except for specialty resins and gel 

coats; 45% monomer by weight for low VOC pigmented gel coats; and 50% monomer by 

weight for low VOC specialty resins and clear gel coats. In lieu of using materials that 
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meet the monomer content limits, the existing rule allows the operator to (1) use of closed 

mold system; (2) use resin containing a vapor suppressant, such that the weight loss from 

the VOC emissions does not exceed 60 grams per square meter of exposed surface 

during resin polymerization3) install and operate an APCO-approved VOC control

system that meets a specified capture and control efficiency. In addition to complying with 

the existing rule’s VOC requirements, the operator would need to comply with the 

applicable recordkeeping requirements of the rule and calculate the VOC emissions from 

fiberglass boat manufacturing to demonstrate if the VOC emissions from all fiberglass boat 

manufacturing open molding operations, including related cleaning activities, are less than 

2.7 tons of VOC per 12-month rolling period. 

• As recommended by EPA, the current requirements for VOC control system in Section 

5.1.1.4 would be modified to include a calculation equation that needs to be used by the 

operator in order to demonstrate that the control system should reduce the VOC 

emissions at all times to a level that is not greater than the emissions which would have 

been achieved through the use of compliant materials, compliant equipment, or 

compliant work practices. 

• As recommended by the CTG, work practice standards would be included requiring an 

operator to ensure that all containers with a capacity equal to or greater than 208 liters 

(55 gallons), including those used for on-site mixing of putties and polyputties have a 

cover with no visible gaps in place at all times, except when material is being placed or 

removed from a container, or when mixing or pumping equipment is being placed in or 

removed from a container. 

• Existing Section 6.4 would be deleted because it serves no useful purpose since the 

year of revision of ASTM test method is already specified in the rule itself. EPA has 

historically wanted the District to specify the revision year of the ASTM test method 

instead of stating the term “most recent version of such test method”.

IV. VOC EMISSION AND REDUCTIONS 

1. Rule 4603 VOC Emissions Reduction 

a. Proposed Amendments to Miscellaneous Metal Parts and Products Coating 

Operations 

The ARB emissions inventory database shows that the 2008 annual average baseline 

emission from metal parts and products coating operations is about 0.65 tons of VOC per 

day. The District’s permit database indicates that there approximately 300 permitted 

sources that are subject to Rule 4603. Staff reviewed the reports of inspections 

conducted by the District’s Compliance Division but unable to determine how many 

sources are using extreme performance coating, and how many sources are performing 
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touch-up and repair coating operation. However, since the federal Clean Air Act requires 

ozone nonattainment areas to implement RACT and that the CTGs promulgated by EPA 

constitute RACT requirements, at a minimum, District staff is compelled to incorporate the 

CTG standards into Rule 4603. Any potential VOC emissions reduction resulting from the 

proposed amendments to the miscellaneous metal parts and products portion of the rule 

would be estimated if new information is received by District staff from affected sources 

during the rule development process. 

b. Proposed Amendments for Plastic Parts and Products, and 

automotive/Transportation and Business Machine Plastic Parts and Products 

Coating Operations 

The ARB emissions inventory database shows that the 2008 annual average baseline 

emission from plastic parts and products coating operations is about 0.04 tons of VOC per 

day. The District’s permit database indicates that there are two permitted plastic parts and 

products coating facilities, but they are not subject to the draft amendments to incorporate 

the CTG’s plastic parts and products coating VOC limits because the permitted VOC 

emissions of each facility are less than rule applicability threshold of 2.7 tons per 12-month 

rolling average. There are no automotive/transportation and business machine plastic 

parts and products coating operations currently operating within the District. Therefore, no 

VOC emissions reduction would result from the proposed changes to the rule to include 

the coating VOC limits for plastic parts and products coating operations and coating VOC 

limits for automotive/transportation and business machine parts and products coating 

operations. 

c. Proposed Amendments for Pleasure Craft Coating Operations 

The ARB emissions inventory database shows that the 2008 annual average baseline 

emission from marine coatings (pleasure craft) is about 0.08 tons of VOC per day. A 

review of the seven permitted boat manufacturing and boat repair facilities operating within 

the District showed only one facility with a permit condition on the use of antifoulant 

coating which allows a VOC content limit of 400 grams/liter (3.3 lb/gallon) and a daily VOC 

emission limit of 40 lb/day. The proposed VOC limit is 336 grams/liter (2.8 lb/gallon). 

Assuming the facility uses 10 gallons per day of such coating, the VOC reduction is 

estimated at 5 lb/day (0.0025 ton/day) or 3,175 lb/year (1.6 tons/year). Data on the 

quantity and type of coatings that are being used for pleasure craft coating operations 

within the District is not available at this time. Any potential VOC emissions reduction 

resulting from the proposed amendments would be updated if new information is received 

by District staff from affected sources. 

2. Rule 4684 VOC Emissions Reduction 

The proposed amendments to Rule 4684 incorporates the CTG standards for fiberglass 

boat manufacturing materials which are essentially the same as the emission standards 
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specified in 40 CFR Part 63 Subpart VVVVV. As discussed above, some of the permitted 

fiberglass boat manufacturing facilities are major sources of hazardous air pollutants so 

they are already required to comply with 40 CFR Part 63 Subpart VVVV (National 

Emission Standards for Hazardous Air Pollutants for Boat Manufacturing). Other boat 

manufacturers are neither major sources of either VOC or HAPs, and are below the CTG 

applicability threshold. Therefore, no VOC emissions reduction is anticipated from the 

draft amendments to Rule 4684. 

V. COST EFFECTIVENESS AND SOCIOECONOMIC ANALYSES 

Pursuant to California Health & Safety Code Section 40920.6(a), the District is required to 

analyze the cost effectiveness of new rules or rule amendments that implement Best 

Available Retrofit Control Technology (BARCT) or planning requirements to incorporate all 

feasible measures. The draft amendments to Rule 4603 and Rule 4684 would only add 

federal RACT requirements but not BARCT or all feasible measure, and are therefore not 

subject to the cost effectiveness analysis mandate.

Pursuant to California Health & Safety Code Section 40728.5 (a) an assessment of the 

socioeconomic impacts is not required for any rule or regulation that only adopts a 

requirement that is substantially similar to, or is required by state or federal statute, 

regulation, or applicable formal guidance, such as a federal CTG. Since the proposed 

amendments to Rule 4603 and Rule 4684 implement the CTG standards mandated by the 

federal Clean Air Act, a socioeconomic impact analysis is not required. 

VI. ENVIRONMENTAL IMPACTS 

Pursuant to the California Environmental Quality Act (CEQA), staff investigated the possible 

environmental impacts of the proposed amendments to Rule 4603 and Rule 4684. Based 

on the lack of evidence to the contrary, District staff has concluded that the proposed 

amendments to the rules will not have any significant adverse effects on the environment. 

Staff recommends filing a Notice of Exemption under the provisions of Public Resource 

Code 15061 (b)(3). 

VII. RULE CONSISTENCY ANALYSIS 

As required by California Health & Safety Code Section 40727.2, District staff will prepare 

a rule consistency analysis later in the rule development process that compares the 

elements of amendments with the corresponding elements of other District rules, federal 

regulations and guidelines that apply to the same source category or type of equipment. 

The analysis has indicated that none of the proposed requirements of these rules would 

conflict with federal rules, regulations, or policies covering similar stationary sources. 
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VIII. RULE DEVELOPMENT PROCESS 

In June 2009, as part of the rule development process, in June 2009 District staff mailed 

copies of the proposed amendments to Rules 4603 and 4684 to affected sources, 

interested parties, the public, EPA and ARB to solicit their comments. In addition, the 

notice of the proposed amendments to the rules was also published in a general 

circulation newspaper in each of the eight San Joaquin Valley counties. The commenting 

deadline ended on July 20, 2009. Comments received during the rule development 

process were incorporated into the rule amendments as appropriate. Comments received 

and District responses are discussed in Appendix A of the Final Draft Staff Report. 

The notice of the public hearing for the proposed rules will be published in a general 

circulation newspaper in each of the eight San Joaquin Valley counties and was mailed to 

affected sources, interested parties, the public, EPA and ARB. The public notice will 

solicit written comments to be submitted by mail, and it also identified the name and 

telephone number of the District staff who can answer questions and respond to 

comments. The Receive and File for these proposed actions is scheduled for August 20, 

2009. The public hearing to consider the proposed actions by the District Governing 

Board is scheduled for September 17, 2009. 

IX. REFERENCES 

1. EPA CTG for Miscellaneous Metal and Plastic Parts Coatings (EPA 453/R-08-003), 

September 2008. 

2. EPA CTG for Fiberglass Boat Manufacturing Materials (EPA 453/R-08-004), 

September 2008. 

3. 40 CFT Part 63 Subpart VVVV (National Emission Standards for Hazardous Air 

Pollutants for Boat Manufacturing), August 22, 2001. 

4. SCAQMD Rule 1162 (Polyester Resin Operations) Final Staff Report, November 

2001.