【国外标准】 Standard Test Method for Quantifying Dirt Collection on Coated Exterior Panels (Withdrawn 2009)

Change in color or appearance of coated exterior surfaces due to such factors as dirt collection or retention is undesirable. If Test Method D 3274 or other test methods are used to establish that dirt collection is the primary cause of such a change, this test method can be used to quantify the degree of dirt collection or, more properly, the degree of change in visual appearance of the coated surface due to dirt collection.When used in this manner and with color change, exposure duration and environment specified, this test method can provide a performance specification with respect to dirt collection.This test is only useful as a comparative test.1.1 This test method covers an instrumental procedure for quantifying the degree of dirt collection on exposed exterior coated panels.1.2 This test method is limited to those coated exterior panels with lightness values before exposure significantly greater than those after exposure.1.3 The instrumental readings do not distinguish between mildew growth and other forms of dirt.1.4 This test method measures total dirt collection. Loose dirt may be washed and removed from specimens if only imbedded dirt collection is to be measured.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.