To help make caulking a snap, use a spoon as a silicone applicator. If using fingers, keep a small pail of water near by. Wet fingers smooth the silicone better than dry. To get old silicone off of metal tubs use a long bladed utility knife to cut off the bulk of it. Rub the remaining silicone residue with camp stove fuel (methyl hydrate) or 3M's silicone remover, and a terry cloth rag to get it off. To prevent scratches on fiberglass products, use an edge that is not as sharp as utility knives. Such as a painters 5 in 1 multi tool. Kitchen and bath rated silicone have special fungicides in them to help prevent mildew. Use of other silicone types require more cleaning effort and more frequent changing.