This technique is applicable to dry paint films and varnishes in a variety of forms including the intact dry paint film surface, a notched or other angular cut surface that exposes a cross section of all paint layers, a paint chip, and ground paint film.
The response of the spot test method varies depending on the extractability of lead from a coating matrix, which may differ depending on the test kit used, the coating type tested, and the type of lead pigment (3).
In some situations, metals and other chemical species interfere with the spot tests causing false negative or false positive results (see Section 8).
A spot test result may be used as a negative screen for the presence of lead in paints and varnishes provided the response of the test kit is sensitive to detecting lead reliably at a given predetermined level, for example, a federal or state regulated abatement action level (4).
This practice may be used in conjunction with quantitative analytical methods for lead such as portable X-ray fluorescence, anodic stripping voltammetry, or fixed-site laboratory analysis of paint chip samples.
Colorblind individuals (protanomalous viewers) who are deficient in viewing red colors may have difficulty in discerning the pink or red color of a positive rhodizonate test.
1.1 This practice covers the use of commercial spot test kits based on either sulfide or rhodizonate for the qualitative determination of the presence of lead in dry paint films.
1.2 This practice may also be used as a qualitative procedure for other dry coating films such as varnishes.
1.3 This practice provides a list of the advantages and limitations of chemical spot test kits based on sulfide and rhodizonate to allow the user to choose the appropriate spot test for a given circumstance.
1.4 This practice contains notes which are explanatory and not part of mandatory requirements.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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