EPA Methods List with Links



US EPA Method 24 - Determination Of Volatile Matter Content, Water Content, Density, Volume Solids, And Weight Solids Of Surface Coatings



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1.0 Scope and Application.



1.1 Analytes.



1.2 Applicability.

This method is applicable for the determination of volatile matter content, water content, density, volume solids, and weight solids of paint, varnish, lacquer, or other related surface coatings.



1.3 Precision and Bias.

Intra- and inter-laboratory analytical precision statements are presented in Section 13.1. No bias has been identified.



2.0 Summary of Method.



2.1 Standard methods are used to determine the volatile matter content, water content, density, volume solids, and weight solids of paint, varnish, lacquer, or other related surface coatings.



3.0 Definitions.



3.1 Waterborne coating

Means any coating which contains more than 5 percent water by weight in its volatile fraction.



3.2 Multicomponent coatings

Are coatings that are packaged in two or more parts, which are combined before application. Upon combination a coreactant from one part of the coating chemically reacts, at ambient conditions, with a coreactant from another part of the coating.



3.3 Ultraviolet (UV) radiation-cured coatings

Are coatings which contain unreacted monomers that are polymerized by exposure to ultraviolet light.



4.0 Interferences. [Reserved]




5.0 Safety.



5.1 Disclaimer.

This method may involve hazardous materials, operations, and equipment. This test method may not address all of the safety problems associated with its use. It is the responsibility of the user of this test method to establish appropriate safety and health practices and to determine the applicability of regulatory limitations prior to performing this test method.



5.2 Hazardous Components.

Several of the compounds that may be contained in the coatings analyzed by this method may be irritating or corrosive to tissues (e.g., heptane) or may be toxic (e.g., benzene, methyl alcohol). Nearly all are fire hazards. Appropriate precautions can be found in reference documents, such as Reference 3 of Section 16.0.



6.0 Equipment and Supplies.

The equipment and supplies specified in the ASTM methods listed in Sections 6.1 through 6.6 (incorporated by reference - see 60.17 for acceptable versions of the methods) are required:



6.1 ASTM D 1475-60, 80, or 90, Standard Test Method for Density of Paint, Varnish, Lacquer, and Related Products.



6.2 ASTM D 2369-81, 87, 90, 92, 93, or 95, Standard Test Method for Volatile Content of Coatings.



6.3 ASTM D 3792-79 or 91, Standard Test Method for Water Content of Water Reducible Paints by Direct Injection into a Gas Chromatograph.



6.4 ASTM D 4017-81, 90, or 96a, Standard Test Method for Water in Paints and Paint Materials by the Karl Fischer Titration Method.



6.5 ASTM 4457-85 (Reapproved 1991), Standard Test Method for Determination of Dichloromethane and 1,1,1- Trichloroethane in Paints and Coatings by Direct Injection into a Gas Chromatograph.



6.6 ASTM D 5403-93, Standard Test Methods for Volatile Content of Radiation Curable Materials.



7.0 Reagents and Standards.



7.1 The reagents and standards specified in the ASTM methods listed in Sections 6.1 through 6.6 are required.



8.0 Sample Collection, Preservation, Storage, and Transport.



8.1 Follow the sample collection, preservation, storage, and transport procedures described in Reference 1 of Section 16.0.



9.0 Quality Control.



9.1 Reproducibility (NOTE: Not applicable to UV radiation-cured coatings).

The variety of coatings that may be subject to analysis makes it necessary to verify the ability of the analyst and the analytical procedures to obtain reproducible results for the coatings tested. Verification is accomplished by running duplicate analyses on each sample tested (Sections 11.2 through 11.4) and comparing the results with the intra-laboratory precision statements (Section 13.1) for each parameter.



9.2 Confidence Limits for Waterborne Coatings.

Because of the inherent increased imprecision in the determination of the VOC content of waterborne coatings as the weight percent of water increases, measured parameters for waterborne coatings are replaced with appropriate confidence limits (Section 12.6). These confidence limits are based on measured parameters and inter-laboratory precision statements.



10.0 Calibration and Standardization.



10.1 Perform the calibration and standardization procedures specified in the ASTM methods listed in Sections 6.1 through 6.6.



11.0 Analytical Procedure.

Additional guidance can be found in Reference 2 of Section 16.0.



11.1 Non Thin-film Ultraviolet Radiation-cured (UV radiation-cured) Coatings.



11.1.1 Volatile Content. Use the procedure in ASTM D 5403 to determine the volatile matter content of the coating except the curing test described in NOTE 2 of ASTM D 5403 is required.



11.1.2 Water Content. To determine water content, follow Section 11.3.2.



11.1.3 Coating Density. To determine coating density, follow Section 11.3.3.



11.1.4 Solids Content. To determine solids content, follow Section 11.3.4.



11.1.5 To determine if a coating or ink can be classified as a thin-film UV cured coating or ink, use the equation in Section 12.2. If C is less than 0.2 g and A is greater than or equal to 225 cm2 (35 in2) then the coating or ink is considered a thin-film UV radiation-cured coating and ASTM D 5403 is not applicable.

NOTE: As noted in Section 1.4 of ASTM D 5403, this method may not be applicable to radiation curable materials wherein the volatile material is water.



11.2 Multi-component Coatings.



11.2.1 Sample Preparation.



11.2.1.1 Prepare about 100 ml of sample by mixing the components in a storage container, such as a glass jar with a screw top or a metal can with a cap. The storage container should be just large enough to hold the mixture. Combine the components (by weight or volume) in the ratio recommended by the manufacturer. Tightly close the container between additions and during mixing to prevent loss of volatile materials. However, most manufacturers mixing instructions are by volume. Because of possible error caused by expansion of the liquid when measuring the volume, it is recommended that the components be combined by weight. When weight is used to combine the components and the manufacturer’s recommended ratio is by volume, the density must be determined by Section 11.3.3.



11.2.1.2 Immediately after mixing, take aliquots from this 100 ml sample for determination of the total volatile content, water content, and density.



11.2.2 Volatile Content. To determine total volatile content, use the apparatus and reagents described in ASTM D2369 Sections 3 and 4 (incorporated by reference - see 60.17 for the approved versions of the standard), respectively, and use the following procedures:



11.2.2.1 Weigh and record the weight of an aluminum foil weighing dish. Add 3 + 1 ml of suitable solvent as specified in ASTM D2369 to the weighing dish. Using a syringe as specified in ASTM D2369, weigh to 1 mg, by difference, a sample of coating into the weighing dish. For coatings believed to have a volatile content less than 40 weight percent, a suitable size is 0.3 + 0.10 g, but for coatings believed to have a volatile content greater than 40 weight percent, a suitable size is 0.5 + 0.1 g.

NOTE: If the volatile content determined pursuant to Section 12.4 is not in the range corresponding to the sample size chosen repeat the test with the appropriate sample size. Add the specimen drop-wise, shaking (swirling) the dish to disperse the specimen completely in the solvent. If the material forms a lump that cannot be dispersed, discard the specimen and prepare a new one. Similarly, prepare a duplicate. The sample shall stand for a minimum of 1 hour, but no more than 24 hours prior to being oven cured at 110 + 5C (230 + 9F) for 1 hour.



11.2.2.2 Heat the aluminum foil dishes containing the dispersed specimens in the forced draft oven for 60 min at 110 + 5C (230 + 9F). Caution -- provide adequate ventilation, consistent with accepted laboratory practice, to prevent solvent vapors from accumulating to a dangerous level.



11.2.2.3 Remove the dishes from the oven, place immediately in a desiccator, cool to ambient temperature, and weigh to within 1 mg.



11.2.2.4 Run analyses in pairs (duplicate sets) for each coating mixture until the criterion in Section 11.4 is met. Calculate Wvfollowing Equation 24-2 and record the arithmetic average.



11.2.3 Water Content. To determine water content, follow Section 11.3.2.



11.2.4 Coating Density. To determine coating density, follow Section 11.3.3.



11.2.5 Solids Content. To determine solids content, follow Section 11.3.4.



11.2.6 Exempt Solvent Content. To determine the exempt solvent content, follow Section 11.3.5.

NOTE: For all other coatings (i.e., water- or solvent-borne coatings) not covered by multicomponent or UV radiation-cured coatings, analyze as shown below:



11.3 Water- or Solvent-borne coatings.



11.3.1 Volatile Content. Use the procedure in ASTM D 2369 to determine the volatile matter content (may include water) of the coating.



11.3.1.1 Record the following information:

W1 = weight of dish and sample before heating, g

W2 = weight of dish and sample after heating, g

W3 = sample weight, g.



11.3.1.2 Calculate the weight fraction of the volatile matter (Wv) for each analysis as shown in Section 12.3.



11.3.1.3 Run duplicate analyses until the difference between the two values in a set is less than or equal to the intra-laboratory precision statement in Section 13.1.



11.3.1.4 Record the arithmetic average (Wv).



11.3.2 Water Content. For waterborne coatings only, determine the weight fraction of water (Ww) using either ASTM D 3792 or ASTM D 4017.



11.3.2.1 Run duplicate analyses until the difference between the two values in a set is less than or equal to the intra-laboratory precision statement in Section 13.1.



11.3.2.2 Record the arithmetic average (Ww).



11.3.3 Coating Density. Determine the density (Dc, kg/l) of the surface coating using the procedure in ASTM D.



11.3.3.1 Run duplicate analyses until each value in a set deviates from the mean of the set by no more than the intra-laboratory precision statement in Section 13.1.



11.3.3.2 Record the arithmetic average (Dc).



11.3.4 Solids Content. Determine the volume fraction (Vs) solids of the coating by calculation using the manufacturer's formulation.



11.3.5 Exempt Solvent Content. Determine the weight fraction of exempt solvents (WE) by using ASTM Method D4457. Run a duplicate set of determinations and record the arithmetic average (WE).



11.4 Sample Analysis Criteria.

For Wv and Ww, run duplicate analyses until the difference between the two values in a set is less than or equal to the intra-laboratory precision statement for that parameter. For Dc, run duplicate analyses until each value in a set deviates from the mean of the set by no more than the intra-laboratory precision statement. If, after several attempts, it is concluded that the ASTM procedures cannot be used for the specific coating with the established intra-laboratory precision (excluding UV radiation-cured coatings), the U.S.

Environmental Protection Agency (EPA) will assume responsibility for providing the necessary procedures for revising the method or precision statements upon written request to: Director, Emissions, Monitoring, and Analysis Division, MD-14, Office of Air Quality Planning and Standards, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711.



12.0 Calculations and Data Analysis.



12.1 Nomenclature.

A = Area of substrate, cm2, (in2).

C = Amount of coating or ink added to the substrate, g.

Dc = Density of coating or ink, g/cm3 (g/in>3).

F = Manufacturer’s recommended film thickness, cm (in).

Wo = Weight fraction of nonaqueous volatile matter, g/g.

Ws = Weight fraction of solids, g/g.

Wv = Weight fraction of the volatile matter, g/g.

Ww = Weight fraction of the water, g/g.

12.2 To determine if a coating or ink can be classified as a thin-film UV cured coating or ink, use the following equation:

12.3 Calculate Wv for each analysis as shown below:



12.4 Nonaqueous Volatile Matter.



12.4.1 Solvent-borne Coatings.



12.4.2 Waterborne Coatings.



12.4.3 Coatings Containing Exempt Solvents.



12.5 Weight Fraction Solids.



12.6 Confidence Limit Calculations for Waterborne Coatings. To calculate the lower confidence limit, subtract the appropriate inter-laboratory precision value from the measured mean value for that parameter. To calculate the upper confidence limit, add the appropriate inter-laboratory precision value to the measured mean value for that parameter. For Wv and Dc, use the lower confidence limits; for Ww, use the upper confidence limit. Because Ws is calculated, there is no adjustment for this parameter.



13.0 Method Performance.

13.1 Analytical Precision Statements. The intra- and inter-laboratory precision statements are given in Table 24-1 in Section 17.0.



14.0 Pollution Prevention. [Reserved]




15.0 Waste Management. [Reserved]




16.0 References.

Same as specified in Section 6.0, with the addition of the following:

1. Standard Procedure for Collection of Coating and Ink Samples for Analysis by Reference Methods 24 and 24A. EPA-340/1-91-010. U.S. Environmental Protection Agency, Stationary Source Compliance Division, Washington, D.C. September 1991.

2. Standard Operating Procedure for Analysis of Coating and Ink Samples by Reference Methods 24 and 24A. EPA-340/1-91-011. U.S. Environmental Protection Agency, Stationary Source Compliance Division, Washington, D.C. September 1991.

3. Handbook of Hazardous Materials: Fire, Safety, Health. Alliance of American Insurers. Schaumberg, IL. 1983.



17.0 Tables, Diagrams, flowcharts, and Validation Data.

TABLE 24-1. ANALYTICAL PRECISION STATEMENTS.