(a) To determine the density of a finish, the reference method is EPA Method 24 of appendix A of 40 CFR part 60. You may use EPA Method 24, an alternative method approved by the Administrator, or any other reasonable means for determining the density of a finish. Other reasonable means of determining density include, but are not limited to, an MSDS or a manufacturer's hazardous air pollutant data sheet. If the density is provided on a MSDS or a manufacturer's data sheet as a range of values, then the highest density value of the range must be used for the determination of compliance to this standard. This value must be entered on the finish log for each type of finish applied. You are not required to test the materials that you use, but the Administrator may require a test using EPA Method 24 (or another approved method) to confirm the reported density. However, if the results of an analysis by EPA Method 24 are different from the density determined by another means, the EPA Method 24 results will govern compliance determinations.

(b) You may use the weighted average of finish densities as determined in paragraph (a) of this section for each finish when you perform one of the actions listed in paragraphs (b)(1) and (2) of this section:

(1) Mix your own finishes on site.

(2) Mix new quantities of finish with previous quantities of finish that may have different densities.

(c) Equation 1 of this section may be used to determine the weighted average of finish densities, as follows:

$$ Where: Average Weighted Density = The average weighted density of applied finishes in pounds per gallon. Mass = Pounds of finish “i” applied. Density = The density of finish “i” in pounds per gallon. n = Number of finish types applied.