ASTM D662-93 pdf free.Standard Test Method for Evaluating Degree of Erosion of Exterior Paints.
The photographic reference standards that are part ofthis test method and are provided in the Pictorial Standards ofCoating Defects Handbook are representative of the degree oferosion of exterior paint films.Fig. 1 is for illustration purposesonly and should not be used for evaluation.
The use of the photographic reference standards illustrated in Fig.1 requires the following precautions:Care must be taken not to confuse various types offailure that may be present on the same surface.It must be realized that the degree of failure will varyover any given area. Therefore, an average portion of the filmshould be used for comparison. On larger surfaces it isrecommended that ratings be made at several locations and themean and range reported.
The photographic standards used represent variousdegrees of erosion of a white brushing type paint over a darkprimer. This system was necessary to provide sufficient contrast for photographic purposes.The erosion of a film to itsnormal substrate is, however, readily visible to the naked eyeso it may easily be compared to the standards and given anumerical rating.In doubtful cases, erosion is sometimes more visible ina damp film than in a dry film. Also,with severe erosion, it isoften easier to rate the degree of erosion in a damp film than ina dry film.While erosion of a sprayed film is more regular in itswearing away,a numerical rating can be given to it byinterpreting the amount of erosion in terms of these standards.6.3 For convenience in recording the data obtained，therecords should be kept on forms agreed upon between thepurchaser and the seller.
No precision or bias statement has been established forthis test method. Erosion failure of paint films can occur in use.This testmethod provides a mean of evaluating the degree of failure bycomparing to pictorial standards.ASTM D662 pdf download.