Old silicone removal?

AlexSchmoll · #1 (**permalink**) 12-02-2006

Hi: Does anyone have experience with removing old silicone sealant. I've got a new (old) boat that has copious amounts of old cured sealant slopped around fittings, hatches, instruments etc. that doesn't want to budge. I have seen a couple of products advertised that will apparently dissolve and remove the old stuff, but am concerned about damaging the gelcoat. Any tried and true suggestions? Thanks!

Alex

sailingfool · #2 (**permalink**) 12-02-2006

Silicone usually isn't hard to get off, you can use a scrapper or even a fingernail. However, if yours is difficult or resistant, try this stuff

http://www.boatersworld.com/product/376970950msk.htm

sailingdog · #3 (**permalink**) 12-02-2006

Silicone generally isn't all that strong an adhesive...it generally is used to make gaskets rather than work as a sealant due to its weak adhesion properties. The one time you will generally need to use a chemical cleaner is to get rid of the residues that it leaves behind. The residues can cause problems with paint adhesion and usually will leave "fisheyes" in the paint.

BeneteauMark · #4 (**permalink**) 12-03-2006

I haven't had to take silicone off a boat, but did have to remove it from a camper. The project was resealing a leaking window, and a previous owner had removed the rather sloppily resealed it with silicone. Couldn't get the silicone to let go of the aluminum window frame or the skin of the campler. Tried several solvents (mineral spirits, acetone, etc.) and settled on Interlux 222 (their fiberglass dewaxing solvent). It caused the silicone to lose adhesion and come off nicely, though I want through a lot of 222 and shop towels. The 222 evaporated so quickly that I had to keep re applying it.

Also, I found a silicone remover at my local Ace hardware recently. Bought some ($15 for a caulking gun size tube), but haven't tried it yet.

Mark

AlexSchmoll · #5 (**permalink**) 12-03-2006

Thanks all for the suggestions -- the residue is nasty and needs some kind of help other than scraping.

Alex

BigBoatSailor · #6 (**permalink**) 12-09-2006

Last year, I had to remove the forward section of my Hunter 34 cabin sole that was entirely set in silicone. What the guys are saying about taking the bulk of it off is right on. It comes off relatively easy. I used a 4" blade razor blade type wallpaper scraper and essentially peeled it all off or at least cut the heavy stuff off.

The big problem is you MUST get all the residue off... the stuff you can't see. If you don't, your new caulking will not stick. Acetone, mineral spirits, alcohol, MEK and other petroleum based solvents will not touch it. It has to be squeaky clean like window glass.

I used Contractors Grade De-Solve-It. Ace has it in two size trigger spray bottles. It looks a little like Goo Gone. Spray it on and let it sit for awhile. Then you can use a Scotch Brite pad and/or scrub brush to remove it. It rinses with water. You may have to do a couple of applications to make sure nothing is left.

Bob