This specification covers measurement of strain resistance of anodic coatings on aluminium and its alloys, that have undergone a sealing treatment and contact with an acidic solution, are stainproof or nonadsorptive with respect to dyes. The method comprises contacting the test area of the anodized specimen with nitric acid solution and, after rinsing and drying, applying a special dye solution followed by rinsing and rubbing the test area with pumice powder, drying, and visual examination of the test area for retention of dye stain. Coatings that exhibit no dye stain or change in color are considered to have passed the test. Reagent grade chemicals shall be used in all tests. A specified solution of nitric acid shall be prepared in distilled or deionized water. A specified volume of aluminium blue 2WL dye shall be dissolved in distilled or deionized water.