16 C.F.R. § 1109.21 Composite testing.
(a) Paint. In testing paint for compliance with chemical content limits, certifiers and testing parties may procure tests conducted on a combination of different paint samples so long as test procedures are followed to ensure that no failure to comply with the lead limits will go undetected (see paragraph (c) of this section). A certificate may be based on testing each component part of the paint according to the requirements of § 1109.11 and certifying that each component part in the mixture individually complies with the lead in paint limit or other paint limit. Testing and certification of composite paints must also comply with §§ 1109.5 and 1109.11.
(b) Component parts. A certifier or testing party may procure tests conducted on a combination of component parts for compliance with chemical content limits so long as test procedures are followed to ensure that no failure to comply with the content limits will go undetected (see paragraph (c) of this section). Testing and certification of composite component parts for lead content must also comply with §§ 1109.5 and 1109.12. Testing and certification of composite component parts for phthalate content must also comply with §§ 1109.5 and 1109.13.
(c) How to evaluate composite testing. When using composite testing, only the total amount or percentage of the target chemical is determined, not how much was in each individual paint or component part. Therefore, to determine that each paint or component part is within the applicable limit, the entire amount of the target chemical in the composite is attributed to each paint or component part. If this method yields an amount of the target chemical that exceeds the limit applicable to any paint or component part in the composite sample, additional testing would be required to determine which of the paints or component parts, if any, fail to meet the applicable limit.