Recommended for ASTM Method D 3258, Test for Stain Resistance and Porosity
This is a proprietary composition of pigment and dark colored dye dispersed in an organic liquid vehicle. When applied and then removed from a paint film, the intensity of the resultant stain indicates the degree of film porosity. ST-31 is more effective than other media recommended for this purpose.
 
Both media have perfect package stability and are manufactured and control tested to assure batch-to-batch uniformity. Their usefulness extends not only to ASTM tests, but to any soil and stain removal test procedure. Supplied in 4 fl.oz. (118 mL) cans or jars.