ASTM B487-85 (R2013) pdf free.Standard Test Method for Measurement of Metal and Oxide Coating Thickness by Microscopical Examination of Cross Section.
1.1 This test method covers measurement of the local thickness of metal and oxide coatings by the microscopical examination of cross sections using an optical microscope.
1.2 Under good conditions， when using an optical microscope, the method is capable of giving an absolute measuring accuracy of 0.8 um. This will determine the suitability of the method for measuring the thickness of thin coatings.
1.3 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. (This is especially applicable to the chemicals cited in Table X2.1.)
2.1 A full width sample is placed on the light table, and the pinholes are counted in a sample of known area (five or more square feet).
3.1 Foil in thickness of about 0.002 in. (0.05 mm) and heavier is virtually free of pinholes. With decrease in thickness, the number of pinholes may increase.
3.2 This method is provided to develop and maintain uniformity in the methods of evaluating pinholes in aluminum foil. The pinhole data provides assessments of process capability and quality levels of the foil as well.
4.1 A light table which provides illumination between 1500 and 1800 lux light intensity with a smooth and uniform inspection surface on which the foil is examined. The light table must be in a black booth or in an area where the lights are turned off to provide darkness of less than 50 lux. The light table should be able to accommodate the widest width of foil to be examined. The usual construction of the light table consists of a shallow box painted white on the inside with rows of fuorescent lights and with a frosted or milk glass covering to provide uniform light diffusion.
4.3 One or more counting frames (grids) that have openings of one square foot (one square decimeter for SI counts).ASTM B487 free download.