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I am changing my deck mounted running lights; the old lights were "bedded" with about 1/2" of silicone. I've managed to get a lot of it off, but the last bit doesn't want to go. What is the best way to get this off? I've tried vinegar, IPA and scraping. . .
No chemical will help.
My own process for removing silicone is:
1) using a chisel on the largest amounts
2) using a knife (I have an old kitchen "steak" type knife with a relatively flexible blade) on what remains
3) using sandpaper on the surface to remove the "residue" (check by wiping some water on it - if water no longer "beads" or "pools" - silicone is finally gone).
While doing that, I keep cursing the PO and whoever was the first dumass that thought up the idea of using silicone as a sealant on a boat.
(Just had to rebed the dorade boxes and, you guessed it, more silicone)
That said, it does help in some cases if silicone is applied over something like paint that can be dissolved by acetone - in which case silicone may somewhat come off with underlying material. This does not generally help on FRP.
That said, it does help in some cases if silicone is applied over something like paint that can be dissolved by acetone - in which case silicone may somewhat come off with underlying material. This does not generally help on FRP.
Unfortunately, the oil from the silicone is a pernicious contaminant on fiberglass and very difficult to get rid of. If you think you've gotten rid of it all—an easy way to check is to pour water over the surface.... if it beads at all, instead of wetting the surface, you failed.
One thing that worked for me was the Interlux fiberglass solvent wash. It broke the silicone down (it became crumbly) where I could scrape and wipe it off. Had to use a lot of solvent, but it worked.
Also, I've seen a silicone remover at Ace hardware. It comes in a caulking gun tube, and it's not cheap, but could be worth a try.
Curious, there is an ACE store near my marina - I think I am going to buy a tube and try it. As long as it does not dissolve fiberglass - it may be a good solution, finally.
The only chemicals, that would be readily commercially available, that are not recommended for long term use with silicone are Xylene and Toluene.
Silicone is highly resistant to Acetone and also to mineral spirits/stoddard solvent (which is basically WD-40). While over time mineral spirits/stoddard solvent may cause swelling to the surface of the silicone it will NOT remove silicone contamination from fiberglass or gelcoat. Just because you rubbed the visible residue from the surface does not mean it is not still silicone contaminated..
The only real cure for silicone contamination is wet sanding. Xylene and Toluene would need to be in contact with the gelcoat for a LONG time to remove any silicone and doing so may harm the substrate..
Trust me I have tried many tactics over the years and NOTHING removes the underlying contamination better than wet sanding.
If you aren't concerned with saving the paint, try brake cleaner. Methylene chloride, if you still find it, is the best silicone remover. For a safer chemical, 3M makes a spray remover; and their Prep Solvent 70 is used by auto painters to clean off residual silicone, supposedly with excellent results. YMMV.
Methylene Chloride is a very nasty chemical and should not be used unless you're wearing a respirator and heavy gloves, full face mask... as it is skin absorbable and highly carcinogenic.
My old, weathered, white, textured, gelcoat deck has no objections either strcturally or visually in the prudent use of a stainless steel "tooth brush". It picks out the residual bits. In tough situations I use a mild wire brush in my portable electric drill. I just re-bedded all my deck hardware last week.
fiestaMojo, if you are planning to replace the old lights with new ones, you probably don't need to be too concerned with trying to remove all traces of the old silicone.
If that is the case, then you may want to try using a wire wheel on a 4" hand grinder. I have used a steel one to successfully removing 5200 from gelcoat. However, if I were concerned with damaging the deck, I would use a softer bronze wheel.
Actually the WD-40 worked quite well at "loosening" up the old silicone, just a little scraping with a razor blade afterwards did the trick. Now, what should I use when mounting the new lights? I have a pair of Innovative Lighting LED navigation lights (got them for a good price), and a Perko-style stern light (the foam rubber gasket/brass mounting plate set up).
No actinic will help.
My own action for removing silicone is:
1) application a brand on the better amounts
2) application a knife (I accept an old kitchen "steak" blazon knife with a almost adjustable blade) on what remains
3) application sandpaper on the apparent to abolish the "residue" (check by wiping some baptize on it - if baptize no best "beads" or "pools" - silicone is assuredly gone). While accomplishing that, I accumulate cursing the PO and whoever was the aboriginal dumass that anticipation up the abstraction of application silicone as a adhesive on a boat.
I just removed a bunch of silicone from a rub rail. Please see my other thread on what I used. It worked great. (Hey, it's really late here.) Hope that helps.
I was talking to Catalina customer service. They recommend the use of "Anti-Bond", and promise I will be pleased. It is in the West Marine data base, but, unfortunately, for some reason (related to the danger element in the chemical?) not available in Canada...
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