General purpose seam compound is to be used above the waterline under topside enamels or below the waterline under antifouling paints. They are knifed into a clean, sealed or primed seam. 7110:The white can be used under varnish on decks. These compounds are fairly stiff and can be softened by heat. 7510: Seam Cement is made from rosin and oils that are fully compatible with soft antifouling paints. Paintable after overnight dry. The Seam Cement is not too stiff and can be easily knifed into seams below the waterline.