If you make your life repairing boats - you would require a license to buy and use silicone sealant on boats. Terrible ramifications for additional work down the road. Use any of the other sealants recommended here on the thread. Watch that 5200 - try 4200 instead. My $.02 And worth every bit. GO An Ex-MIP and feeling better about it every day! **************Get trade secrets for amazing burgers. Watch "Cooking with Tyler Florence" on AOL Food. (http://food.aol.com/tyler-florence?video=4&?NCID=aolfod00030000000002)