EKAPCD 432 - 0 3/13/2014 

RULE 432 Polyester Resin Operations - Adopted 3/13/2014 

I. Applicability

The purpose of this rule is to reduce volatile organic compounds (VOC) emissions from 

polyester resin operations. The provisions of this rule apply to commercial polyester resin 

operations, industrial polyester resin operations, and organic solvents (use {including 

cleaning}, storage, waste, and disposal {off-site transfer}) associated with polyester resin 

operations. 

II. Definitions

A. APCO: Air Pollution Control Officer of the Eastern Kern Air Pollution Control 

District. 

B. Application Equipment: Device, including, but not limited to, a spray gun, brush, and 

roller, used to apply adhesives, coatings, or inks. 

C. ARB: California Air Resources Board. 

D. Assembly Adhesive: Chemical material used to join two or more fiberglass, metal, 

foam, plastic, or wood parts. Assembly adhesives include, but are not limited to, 

methacrylate adhesives and putties made from polyester or vinylester resin mixed with 

inert filler or fibers. 

E. ASTM: American Society of Testing and Materials International. 

F. Atomized Resin Application: Technology that utilizes application equipment that 

breaks resin into droplets (or aerosol) as it exits application equipment to the surface of 

the part. Atomized resin application includes, but is not limited to, resin spray guns and 

resin chopper spray guns. 

G. Bench Scale Project: Project (not located at Research and Development facility) 

operated on a small scale, such as one capable of being located on a laboratory bench 

top. 

H. Catalyst: Substance is added to a resin to initiate or promote polymerization. 

I. CFR: Code of Federal Regulations. 

J. Cleaning Materials: Materials including, but not limited to, materials used for cleaning 

hands, tools, molds, application equipment, and work areas. 

K. Clear Gel Coat: Clear (translucent) gel coating used to allow underlying colors or 

patterns to be visible. Tooling gel coat used to build or repair molds is NOT a clear gel 

coat. 
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L. Closed Molding Process: Molding process that utilizes pressure to distribute resin 

through the reinforcing fabric placed between two mold surfaces to either saturate the 

fabric or fill the mold cavity. Pressure utilized can be one or combination of the 

following forms: clamping, fluid (hydraulic), vacuum, or atmospheric. Mold surfaces 

may be rigid or flexible. Closed molding includes, but is not limited to, compression 

molding with sheet molding compound, infusion molding, resin injection molding 

(RIM),vacuum-assisted resin transfer molding (VARTM), resin transfer molding 

(RTM), and vacuum-assisted compression molding. The following are not close 

molding processes: 

1. Processes utilizing a closed mold to compact saturated fabric or remove air or 

excess resin from the fabric (such as in vacuum bagging). 

2. Open molding steps, such as application of gel coat or skin coat layer by 

conventional open molding prior to a closed molding process. 

M. Coating: A material applied onto or impregnated into a substrate for protective, 

decorative, or functional purposes. 

N. Corrosion-Resistant Material: Polyester resin material used to make products for 

corrosion resistant applications such as tooling, fuel or chemical tanks, boat hulls, pools 

and outdoor spas. 

O. Cure: Polymerization process where small molecules, called monomers, combine 

chemically to produce a very large chainlike or network molecule. Chemicals are 

transformed from a liquid to a solid state or semisolid state to achieve desired physical 

properties for the product, including hardness. 

P. Cured Coating: Coating that is dry to the touch. 

Q. Degreaser: Solvent containing tank, tray, drum, etc. utilized to clean objects. Objects 

are cleaned by immersion into solvent or exposure to solvent vapor. Objects include, 

but not limited to, parts, products, tools, machinery, and equipment. An enclosed spray 

application equipment cleaning system is not a degreaser. 

R. Dissolver: Organic solvent that is added to an adhesive, coating, or ink to melt or to 

liquefy solid particles. 

S. EPA: United States Environmental Protection Agency. 

T. Filament Application: Resin application method to an open mold where reinforcement 

fibers are fed through a resin bath and winding the resin impregnated fibers on a 

rotating mandrel. 

U. Filled Polyester Resin Material: Material formulated by adding compatible filler(s) to 

polyester resin material(s). 
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V. Filler: Inert (non-VOC) substance added to the resin to enhance its mechanical 

properties or extend its volume. Resin fillers include, but are not limited to, silica, 

carbon black, talc, mica and calcium carbonate. 

W. Fire Retardant Material: Polyester resin material used to make products that are 

resistant to flame or fire. 

X. Fluid Impingement Technology: Spray gun that produces an expanding non-misting 

curtain of liquid by the impingement of low-pressure uninterrupted liquid streams. 

Y. Gel Coat: Polyester resin topcoat that provides a cosmetic enhancement and improves 

resistance to degradation from environmental exposure. 

Z. Grams of VOC per Liter of Material: The weight of VOC per volume of material and 

can be calculated by the following equation: 

Ws - Ww - Wec Grams of VOC per liter of material = Vm 

Where: 

Ws = weight of volatile compounds (grams) 

Ww = weight of water (grams) 

Wec = weight of exempt compounds (grams) 

Vm = volume of material (liters) 

AA. High-Strength Material: Polyester resins which have a casting tensile strength of 

10,000-psi or more. 

BB. High-Volume, Low-Pressure (HVLP): Spray equipment permanently labeled as such 

and which is designed and operated between 0.1 and 10 pounds per square inch, gauge, 

(psig) air atomizing pressure measured dynamically at the center of the air cap and at 

the air horns and with liquid supply pressure less than 50 psig. 

CC. Lamination Resin: Orthophthalate, isophthalate and dicyclopentadiene (DCPD) resin 

which is used in composite system made of layers of reinforcement fibers and resins. 

DD. Liquid Leak: Visible solvent leak from a container at a rate of more than three drops 

per minute, or a visible liquid mist. 

EE. Maintenance Cleaning: Cleaning of tools, forms, molds, jigs, machinery, and 

equipment (excluding coating, ink and adhesive application equipment), and the 

cleaning of work areas where maintenance or manufacturing occurs. 

FF. Manual Application: Application of resin to an open mold using a hand layup 

technique. Components of successive plies of resin-impregnated reinforcement fibers 

are applied using hand tools such as brushes and rollers. 

GG. Manufacturing Process: Process of making goods or products by hand or by machine. 

HH. Marble Resin: Orthophthalate and modified acrylic isophthalate resin, which is 

designed for the fabrication of cast products, such as vanities. 
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II. Mold: Cavity or surface where gel coat, resin, and fibers are placed and from which 

finished fiberglass parts take their form. 

JJ. Monomer: Organic compound, such as styrene, that reacts with unsaturated polyester 

resins to form a cured polyester resin. 

KK. Month: Calendar month. 

LL. Neat Resin: Resin that has no added filler. 

MM. Non-Absorbent Container: Container made of non-porous material that does not allow 

the migration of solvents through it. 

NN. Non-Atomized Resin Application: Technology that utilizes application equipment that 

does not break resin into droplets (or aerosol) as it exits application equipment to the 

surface of the part. Non-atomized resin application technology includes, but are not 

limited to, non-atomizing spray guns, flowcoaters, chopper flowcoaters, pressure fed 

resin rollers, resin impregnators, or fluid impingement technology. 

OO. Non-Atomized Solvent Flow: Solvents in the form of a liquid stream without the 

introduction of any propellant. 

PP. Non-Atomizing Spray Gun: Spray gun where resin flows in a steady and observable 

coherent flow, with no droplets formed in the area that is within the first three (3) 

inches of the applicator orifice. Droplets may form in the area greater than three (3) 

inches from the applicator orifice. 

QQ. Non-Leaking Container: Container without a liquid leak. 

RR. Normal Business Hours: Monday through Friday, 8:00 am to 5:00 pm. 

SS. Open Molding Resin and Gel Coat Process: Process where reinforcing fibers and resin 

are placed in an open-air mold while the reinforcing fibers are saturated with resin. 

Open molding operations include vacuum bags (or similar) used to compress uncured 

laminate to remove bubbles, excess resin, and to achieve a bond between core material 

and laminate. 

TT. Organic Solvent: The same as “Solvent.” 

UU. Organic Solvent Cleaning: Activity, operation, or process, (including surface 

preparation, cleanup, or wipe cleaning), performed outside of a degreaser, that uses 

organic solvents to remove uncured adhesives, uncured coatings, uncured inks or other 

contaminants. These operations including, but not limited to, dirt, soil, oil, lubricants, 

coolants, moisture, fingerprints, and grease, from parts, products, tools, machinery, 

general work areas and application equipment (including coatings, adhesives, and ink 

spray equipment). 
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VV. Pigmented Gel Coat: Opaque gel coat that provides a colored, glossy surface which 

improves the aesthetic appearance of the products. Pigmented gel coat does not include 

tooling gel coat used to build or repair molds. 

WW. Polyester Resin Materials: Materials including, but not limited to: unsaturated 

polyester resins such as isophthalic, orthophthalic, halogenated, Bisphenol-A, vinylester, or furan resins; cross-linking agents; catalysts, gel coats, inhibitors, accelerators, 

promoters, and any other materials used in polyester resin operations. 

XX. Polyester Resin Operations: Production or rework of products by mixing, pouring, 

hand layup, impregnating, injecting, forming, winding, spraying, and/or curing with 

fiberglass, fillers, or any other reinforcement materials and associated cleanup. 

YY. Polymer: Chemical compound comprised of a large number of chemical units, formed 

by chemical linking of monomers. 

ZZ. Production Resin: General purpose resin material that is not especially corrosion 

resistant, fire retardant, high strength, or gel coats. 

AAA. Propellant: Gas, including air, in a pressure container utilized to expel the contents 

when the pressure is released. 

BBB. Repair Cleaning: Solvent cleaning operation or activity carried out during a repair 

process. 

CCC. Repair Process: Process of returning a damaged or not operating properly object to 

good condition. 

DDD. Research and Development: Facility or part of a facility used to development useful 

materials, devices, systems, or methods, including, but not limited to, design, 

development, and improvement of prototypes and processes. Research and 

development does not include the production manufacturing operations. 

EEE. Resin: Class of natural or synthetic organic polymers used to encapsulate and bind 

together reinforcement fibers in the construction of fiberglass parts. 

FFF. Resin and Gel Coat Operation: Operation in which resins or gel coats (including 

putties or polyputties) is combined with additives (including, but are not limited to, 

fillers, promoters, or catalysts). 

GGG. SCAQMD: South Coast Air Quality Management District. 

HHH. Skin Coat: Layer of resin and fibers applied over gel coat to protect the gel coat from 

deformation by the subsequent laminate layers. 

III. Small Job: Minor resin or gel coat application project which requires only a very 

limited amount of materials. Total material use for all small jobs at a facility shall not 

exceed two (2) gallons a day. 
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JJJ. Solid Surface Resin: Resin, used without gel coats, to fabricate homogenous solid 

surface products. 

KKK. Solvent: As defined in Rule 410.3, Organic Solvent Degreasing Operations. 

LLL. Specialty Gel Coat: Gel coat used in conjunction with fire retardant, corrosion resistant 

or high-strength materials. 

MMM. Specialty Resin: Halogenated, furan, bisphenol A, vinyl-ester, or isophthalic resin used 

to make products for exposure to one or more of the following extreme environmental 

conditions: corrosive agents, caustic agents, acidic agents, or flame (heat). 

NNN. Stationary Source: As defined in Rule 210.1 (New and Modified Stationary Source 

Review Rule). 

OOO. Tooling Resin: Resins used to build or repair molds (tools) or prototypes (plugs) that 

comprise the molds. 

PPP. Tooling Gel Coat: Gel coat used to build or repair molds (tools) or prototypes (plugs) 

that comprise the molds. 

QQQ. Touch-up: Application of resin or gel coat to correct minor cosmetic imperfections that 

occur during fabrication or field installations. 

RRR. Tub/Shower Resin: Dicyclopentadiene (DCPD), orthophthalate and isophthalate resins, 

used to fabricate bath ware products. 

SSS. Vapor Suppressant: Substance added to resin to minimize the transfer of monomer 

vapor into the atmosphere. 

TTT. Vinylester Resin: Thermosetting resin containing esters of acrylic or methacrylic acids 

having a double-bond and ester linkage sites at the end of the resin molecules. 

UUU. Volatile Organic Compound (VOC): As defined in Rule 102, Definitions. 

VVV. Waste Materials: Materials including but not limited to paper or cloth used for cleaning 

operations, waste resins, or spent cleaning materials. 

III. Exemptions

A. The provisions of this rule, excluding recordkeeping requirements of Section V.A, shall 

not apply to any polyester resin operation provided the volume of polyester resin 

materials used is less than 20 gallons per month. 

B. The solvent cleaning provisions of Section IV.B.2, Table 1 shall not apply to the 

following applications: 

1. Cleaning of solar cells, laser hardware, scientific instruments, or high precision 

optics. 
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2. Cleaning in laboratory tests and analyses, or bench scale or research and 

development projects. 

IV. Requirements

A. Polyester Resin Operation

1. An operator of a polyester resin operation shall comply with the following process 

or control requirements: 

Use materials in an open molding process that comply with the weighted average 

monomer VOC content limits in Table 1. In addition to complying with Table 1 

limits, the non-monomer VOC content of each resin and gel coat shall not contain 

more than 5 percent by weight of the resin or gel coat; or comply with Sections 

IV.A.2, IV.A.3, or IV.A.4. 

TABLE 1

VOC CONTENT LIMITS FOR OPEN MOLDING RESIN AND GEL COAT

Compliant Materials Weighted Average Monomer 

Material Weight Percent Limit 

a. General Purpose Resin 

 Marble Resin 10% or 32%, as supplied, with no fillers 

 Solid Surface 17% 

 Tub/Shower Resin 24% or 35%, as supplied, with no fillers 

 Lamination Resin 31% or 35%, as supplied, with no fillers 

b. Tooling Resin 

 Atomized (spray) 30% 

 Non-atomized 29% 

c. Specialty Resin 

 Fire Retardant Resin 38% 

 High Strength Materials 40% 

 Corrosion Resistant Resin 48% 

d. All Other Resins 35% 

e. Tooling Gel Coat 40% 

f. Pigmented Gel Coat 

 White and Off White 30% 

 Non-White 37% 

 Primer 28% 

g. Clear Gel Coat 

 Marble Resin 40% 

 Other Resin 44% 

h. Specialty Gel Coat 48% 
2. Use resin containing a vapor suppressant, such that the weight loss from the VOC 

emissions does not exceed 50 grams per square meter of exposed surface during 

resin polymerization; 

3. Use a closed-mold system; or 

4. Install and operate a VOC emissions control system which meets all of the 

requirements of Sections IV.A.4.a. through IV.A.4.c during periods of emission 

producing activities: 

a. The VOC emission control system shall be approved, in writing, by the APCO. 

b. The VOC emission control system shall have an overall capture and control 

efficiency of at least 90 percent by weight, demonstrated using the applicable 

test method(s) in Section V.B. 

c. The VOC emission control system shall reduce VOC emissions, at all times, to 

a level that is not greater than the emission which would have been achieved 

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

work practices, as applicable. The following equation shall be used to determine 

if the minimum required overall capture and control efficiency of an emission 

control system is at an equivalent or greater level of VOC reduction as would be 

achieved using compliant materials, equipment, or work practices: 

VOC LWc 1-(VOC LWn,Max / Dn,Max ) CE = 1- x 100 VOC LWn,Max

x 1- (VOC LWc / Dc) 

Where: 

CE = Minimum Required Overall Capture and Control 

Efficiency, percent. 

VOCLWc = VOC Limit, less water and exempt compounds. 

VOCLWn,Max = 

Maximum VOC content of noncompliant coating used 

in conjunction with a control device, less water and 

exempt compounds. 

Dn,Max = 

Density of solvent, reducer, or thinner contained in the 

noncompliant coating, containing the maximum VOC 

content of the multi-component coating. 

Dc = Density of corresponding solvent, reducer, or thinner 

used in the compliant coating system. 

5. Resins and gel coats used for touch up, repair, or small jobs, may have a monomer 

content limit up to 10% more than the applicable limit set forth in Table 1. Such 

resins or gel coats shall only be applied by a hand-held atomized spray gun which 

has a container for the resin or gel coat as part of the gun. Resins or gels applied by 

another method shall comply with the applicable limit in Table 1. Total material 

use for all small jobs at a facility shall not exceed two (2) gallons a day. 

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B. Spray application of polyester resin shall only be performed using airless, air assisted 

airless, high-volume, low-pressure (HVLP) spray equipment, or electrostatic spray 

equipment. 

1. High-Volume, Low-Pressure (HVLP) spray equipment shall be operated in 

accordance with the manufacturer's recommendations. 

2. For HVLP spray guns manufactured prior to January 1, 1996, the end user shall 

demonstrate that the gun meets HVLP spray equipment standards. Satisfactory 

proof will be either in the form of manufacturer's published technical material or by 

a demonstration using a certified air pressure tip gauge, measuring the air atomizing 

pressure dynamically at the center of the air cap and at the air horns. 

3. A person shall not sell or offer for sale for use within the District any HVLP spray 

gun without a permanent marking denoting the maximum inlet air pressure in psig 

at which the gun will operate within the parameters specified in Section II. 

C. In lieu of complying with the applicable requirements of IV.B, an operator may install 

and maintain a VOC emission control system that meets the requirements of Section 

IV.A.4 around the coating application operation. 

TABLE 2 

VOC CONTENT LIMITS FOR ORGANIC SOLVENTS

Type of Solvent Cleaning Operation VOC Content Limit Grams of 

VOC/liter of material (lb/gal) 

a. Product Cleaning During 

Manufacturing Process or Surface 

Preparation for Coating Application 

25 (0.21) 

b. Repair and Maintenance Cleaning 25 (0.21) 

c. Cleaning of Polyester Resin 

Application Equipment 25 (0.21) 

2. In lieu of complying with the VOC content limits in Table 2, an operator may 

control VOC emissions from cleaning operations with an APCO-approved VOC 

emission control system that meets the requirements of Section IV.A.4 for the 

solvent cleaning operations. 

E. Solvent Storage and Disposal

An owner or operator shall store or dispose of all uncured polyester resin materials, 

fresh or spent solvents, waste solvent cleaning materials such as cloth, paper, etc., 

coatings, adhesives, catalysts, and thinners in self-closing, non-absorbent and nonleaking containers. The containers shall remain closed at all times except when 

depositing or removing the contents of the containers or when the container is empty. 
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V. Administrative Requirements

A. Recordkeeping

An operator subject to this rule shall maintain the following records: 

1. Daily records of the type and quantity of all resins, gel coats, fillers, catalysts, and 

cleaning materials (including cleaning solvents) used in each operation. Records 

shall also indicate the amount used and VOC content, in weight percent, of all 

polyester resin and gel coat materials used for touch up, repair, and small jobs. 

2. Records of the VOC content, in weight percent, of all polyester resin and gel coat, 

filler materials, including the weight percent of non-monomer VOC content of the 

resin and gel coat, used or stored at the stationary source. 

3. Records of the VOC content of all cleaning materials used and stored at the 

stationary source as specified in Section IV.D. 

4. Records showing the weight loss per square meter during resin polymerization for 

each vapor-suppressed resin. 

5. VOC Emission Control System records an operator using a VOC emission control 

system pursuant to Section IV.A.4 to comply with this rule shall maintain daily 

records of key system operating parameters to demonstrate continuous operation 

and compliance of the VOC emission control system during periods of emissionproducing activities. Key system operating parameters are those parameters 

necessary to ensure compliance, including, but not limited to, temperature, pressure 

drop, and air flow rate. 

6. An operator claiming exemption under Section III shall maintain records of 

polyester materials usage to support the claim of exemption. 

7. The operator shall retain the records specified in Sections V.A.1 through V.A.6, as 

applicable, on site for a period of five years, make the records available on site 

during normal business hours to the APCO, ARB, or EPA, and submit the records 

to the APCO, ARB, or EPA upon request. 

B. Test Methods

The analysis of cleaning materials, polyester resin materials and control efficiency shall 

be determined by the following methods: 

1. The emission rate per square meter of exposed surface during polymerization of 

Polyester Resins is to be determined using: SCAQMD Method 309 (Static Method 

for Determination of Volatile Emissions from Polyester and Vinyl Resins 

Operations), Attachment A, 1/8/91. 

2. Determination of Overall Capture and Control Efficiency of VOC Emission Control 

Systems: 
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a. The capture efficiency of a VOC emission control system's collection device(s) 

shall be determined according to EPA's "Guidelines for Determining Capture 

Efficiency," January 9, 1995 and 40 CFR 51, Appendix M, Test Methods 204-

204F, as applicable, or any other method approved by EPA, ARB, and the 

APCO. 

b. The control efficiency of a VOC emission control system's VOC control 

device(s) shall be determined using EPA Test Methods 2, 2A, or 2D for 

measuring flow rates and EPA Test Methods 25, 25A, or 25B for measuring 

total gaseous organic concentrations at the inlet and outlet of the control 

device(s). EPA Method 18 or ARB Method 422 shall be used to determine the 

emissions of exempt compounds. 

c. For VOC emission control systems that consist of a single VOC emission 

collection device connected to a single VOC emission control device, the 

overall capture and control efficiency shall be calculated by using the following 

equation: 

[CECapture X CEControl] CECapture and Control = 100 

Where: 

CECapture and Control = Overall Capture and Control 

Efficiency, in percent. 

CECapture = Capture Efficiency of the 

collection device, in percent. 

CEControl = Control Efficiency of the 

control device, in percent. 

3. The monomer content of uncatalyzed resin materials is to be determined using 

ASTM D2369-87 (Standard Test Method for Volatile Content of Coatings) or 

SCAQMD Test Method 312. 

4. The VOC content of cleaning materials shall be determined using EPA Method 24 

(40 CFR Part 60, Appendix A). 

5. Determination of emissions of VOC from spray gun cleaning systems shall be made 

using SCAQMD "General Test Method for Determining Solvent Losses from Spray 

Gun Cleaning Systems," October 3, 1989. 

6. The transfer efficiency of alternative coating application methods shall be 

determined in accordance with the SCAQMD method "Spray Equipment Transfer 

Efficiency Test Procedure for Equipment User," May 24, 1989. 

C. Multiple Test Methods

When more than one test method or set of test methods is specified for any testing, a 

violation of any requirement of this rule established by any one of the specified test 

methods or set of test methods shall constitute a violation of this rule. 
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V. Compliance Schedule

A. New Sources

1. Owners or Operators of any facility proposing to install polyester resin operations 

and required to comply with Section IV of this rule shall obtain an Authority to 

Construct (ATC) in accordance with Rule 210.1 prior to installation or operation of 

any polyester resin operation. 

2. Owners or Operators of any facility with polyester resin operations exempt by 

Section III.A of this rule shall maintain records of polyester resin use upon initial 

operations. 

B. Existing Sources

1. Owners or Operators of any facility with polyester resin operations required to 

comply with Section IV of this rule shall obtain a valid Permit to Operate (PTO) or 

an Authority to Construct (ATC), and shall apply for an ATC within 180-days from 

the adoption of this Rule. 

2. Owners or Operators of any facility with polyester resin operations exempt by 

Section III.A of this rule shall commence maintaining records of polyester resin use 

within 180 days of this rule adoption. 

3. Owners or operators with valid PTO(s), required to comply with Section IV of this 

rule shall obtain shall be in full compliance within 12 months after rule adoption. 

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