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? How should I prepare the surface before applying Waterproof Sealant? What temperature can I apply Liquid Rubber Waterproof Sealant? Can I build my final membrane all at once? Comments 0 comments Please sign in to leave a comment.