5.1 In using Practice D3960 to measure the volatile organic compound content of waterborne coatings, precision can be poor for low volatile organic compound content air-dry coatings if the volatile organic weight percent is determined indirectly. The present method directly identifies and then quantifies the weight percent of individual volatile organic compounds in air-dry coatings (Note 6). The total volatile organic weight percent can be obtained by adding the individual weight percent values (Note 7).
Note 6: The present method may be used to speciate solvent-borne air-dry coatings. However, since these normally contain high, and often complex, quantities of solvent, precision tends to be better using other methods contained in Practice D3960, where the volatile fraction is determined by a direct weight loss determination.
Note 7: Detectable compounds may result from thermal decomposition in a hot injection port or from reaction with the extraction solvent. If it can be shown that a material is a decomposition product, or is the result of a reaction with the extraction solvent, then results for that compound should be discounted from the volatile measured by Test Method D6886.
1.1 This test method is for the determination of the weight percent of individual volatile organic compounds in waterborne air-dry coatings (Note 1).
1.2 This method may be used for the analysis of coatings containing silanes, siloxanes, and silane-siloxane blends.
1.3 This method is not suitable for the analysis of coatings that cure by chemical reaction (this includes two-component coatings and coatings which cure when heated) because the dilution herein required will impede the chemical reaction required for these types of coatings.
1.4 This method can be used to determine the weight percent organic content of waterborne coatings in which the volatile organic compound weight percent is below 5 percent. The method has been used successfully with higher content waterborne coatings and with solventborne coatings (Note 2).
1.5 This method may also be used to measure the exempt volatile organic compound content (for example, acetone, methyl acetate, t-butyl acetate and p-chlorobezotrifluoride) of waterborne and solvent-borne coatings. Check local regulations for a list of exempt compounds. The methodology is virtually identical to that used in Test Method D6133 which, as written, is specific for only exempt volatile compounds.
1.6 Volatile compounds that are presen......
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