The black surface turns brown when wet? This is normal on the surface, the waterproofing is not affected. Related articles How do I cover gaps and cracks? What if I see blisters? Is Liquid Rubber Waterproof Sealant environmentally friendly? Can I build my final membrane all at once? Can Waterproof Sealant be put on tarred surfaces? Comments 0 comments Please sign in to leave a comment.