Adequate coating thickness (mil thickness) is necessary to protect polyurethane foam from the effects of ultraviolet degradation. This guide outlines general procedures for sampling and measuring the coating thickness by using slit or core samples.

Thickness of individual lifts of sprayed foam will have a bearing upon foam stability. Core samples are used to determine foam thickness. Compressive strength and core density affect resistance to foot traffic and impact. Specimens from core samples are used to determine these properties using Test Methods D 1621 and D 1622. Visual examinations of core specimens also indicate the quality of adhesion of the coating and the foam, between foam lifts, and between foam and substrate.

Slit samples are used to visually examine the foam's cell structure, the number of coating layers applied, dry film thickness of the coating, and coating adhesion.