In spray polyurethane foam (SPF) roofing, the verge-of-popcorn surface texture is the roughest texture suitable for receiving the protective coating on an SPF roof. The surface shows a texture where nodules are larger than valleys with the valleys relatively cured. This surface is acceptable for receiving a protective coating only because of the relatively cured valleys. However, the surface is considered undesirable because of the additional amount of coating material required to protect the surface properly.
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