Silicone Removal

Breaux

.
Feb 12, 2018
7
Hunter 23 Mandeville, LA
I just purchased an H23 and it appears that one of the previous owners got carried away with Silicone trying to protect the insides from water leaks. There is silicone everywhere; all over the deck, windows and even on the cushions in the main cabin. Does anyone know a safe removal process for this?
 
Sep 8, 2014
2,551
Catalina 22 Swing Keel San Diego
I've done a ton of research on this and tried numerous chemicals personally... Some things seem like they 'help' but nothing I have found is truly effective at removing silicone residue that will be nearly 'forever' trapped.
When I installed a new shower glass shower door in my house I tried an off the shelf H-D silicone remover (It claimed to break the bond between the silicone and the substrate). I 'think' it kinda worked as claimed, but it just smelled like a standard citrus stripper gel and basically I used a flat razor blade in the standard glass crapping knife to manually remove the residue. Coming off of glossy flat tile it was relatively easy. Still, the gel 'silicone remover' didn't do much.

Primarily removing silicone caulking is a mechanical process. Use a stiff plastic scraper to get the majority of it, metal is fine if you are not worried about scratching non sensitive areas. Then progress to a razor blade to get the rest, which only works really well on flat, glossy surfaces. You need to get as much as you can off but getting all the residue off depends on the application. If you have to do a fiberglass or gelcoat repair you MUST grind away the gelcoat or glass to ensure there is no trace of silicone residue. If you are re-bedding hardware, manually scrape an razor the old stuff out and bet meticulous about it. If the area isn't sensitive and will be covered you can sand it, but you'll notice the sand paper get mucked up by the silicone residue. Generally speaking, wherever there is silicone residue and I have to re-bed I do so with butyl tape. It will still give an excellent seal and the silicone residue does not seem to hinder it. If you have to re-bed with a polysulfide or polyurethane, that's when you need to grind/sand the surface to ensure you get all silicone reside. There is NO commerically available chemical I know of that you can 'wipe' on the surface of fiberglass/gelcoat that will dissolve silicone residue trapped in gelcoat or laminate pores. DOW apparently does make a product that is supposed to do this but it is only for sale to industrial customers and I'll be it is really nasty stuff. You can find the SDS on DOW's website.
If you are resealing windows/port-lights that had silicone.... typically, new silicone will seal to cured but clean silicone just fine. The only silicone that should be used for this is DOW 795 and it is NOT expensive, about $8 a tube I think. As long as you manually scrape away the old sealant and razor blade the majority of the film off, new DOW 795 will still stick like crazy, residue in the pores is no concern.
I am a Practical Sailor subscriber... the article linked above recommends a product called RE-MOV for silicone. Actually, the write is pretty convincing and I want to try it, it may make me re-think my statement that there is 'NO commercially available chemical' that is effective at removing silicone residue. They recommend two applications, 20 minute dwell time, 15 minute interval, then scrape off and use a stiff bristle brush to get after the residue. This might be your ticket!

My general rule of thumb; NO SILICONE ON A BOAT (for the average DIY sailor); for the above average DIY sailor or professional; there are only a few places on a boat for silicone: DOW 795 for windows/port-lights, appropriate silicone gaskets and sealants for engine/machinery components, and appropriate plumbing fixtures & that's it, otherwise keep silicone off the boat and out of the hands of the un-informed or illiterate!
 
Jun 25, 2004
1,108
Corsair F24 Mk1 003 San Francisco Bay, CA
This stuff domes not come off easily, or rather it loves to leave a residue. But this stuff helps.

https://www.practical-sailor.com/issues/37_73/features/PS-Tests-Adhesive-Removers_12142-1.html
I've used Re-Mov and it works well in a lot of situations, as long as you follow the directions. I don't think it will take silicone off fabric, but it did remove silicone from smooth gelcoat well enough to eliminate fish eyes when I painted over a 6" x 6" area).

Re-Mov did a very nice job of removing messy residue that a prior owner had smeared in a lot of places on the non-skid on my boat.

I'll repeat: read and follow the directions. It doesn't work the same was as an adhesive remover. I used a plastic spatula under the edges of thick layers. For thin layers, I used a lot of elbow grease and rough terry cloth rags.
 
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Likes: Rick D
Dec 2, 2003
751
Hunter 260 winnipeg, Manitoba
As others have said the first part is mechanical removal. After that I have used kerosene and a scrubby or many paper towels followed by cleaning with alcohol or acetone to get rid of the kerosene residue. I’ve done this with enough success to allow fresh silicone to adhere around tubs and to Lino.

- this should work on most of your solid surfaces, but obviously not on fanbric/soft surfaces. I’m not sure if there would be any issues with acrylics or polycarbonates.
 
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Mar 26, 2011
3,399
Corsair F-24 MK I Deale, MD
You need to follow the instructions. They've studied it. Don't start with random mechanical removal; this can just make it harder.
  • Exactly how to score
  • Soak time
  • Reapplication
You can practically peal it off if you do it right, and you can get 100% bond strength afterwords. Really.
 
Sep 29, 2008
162
Morgan Out Island 33 Pompano Beach
Try staight white vinegar and a stiff scrub brush...not perfect but it dies loosen the stuff up...safe too. Bob
 
Jun 5, 2010
1,107
Hunter 25 Burlington NJ
EXACTLY the answer I would have given, CloudDiver. I've been doing fiberglass work since 1972 and the one absolute bane to all fiberglass repair, maintenance and construction is the whole presence of silicone sealant within about 20 yards of the boat. In my 45-odd-years of hands-on experience, as well as after having grown up with a yacht-designer engineer for a father (and first teacher), the stuff is the very worst.

Salient properties of silicone sealant:
  • Has to be mechanically removed, as you said.
  • Almost always requires remedial gelcoat work after removal.
  • Does not provide strength.
  • Does not hold out water.
  • Is always ugly; attracts mold like it's its primary purpose.
  • Interferes with every polishing and waxing job you will ever do.
  • Clogs all sandpaper rendering it worthless for anything else.
  • Soaks into raw wood just enough to bar all epoxy, sealer, paint, etc. from saturation.
  • Interferes with all other adhesion of hardware and sealing of seams.
  • Makes you look like a moronic motorboater (for some reason motorboaters seem to love the stuff; it's almost a black-white distinction-- motorboater : silicone :: sailboater : polyurethanes.

    If anyone comes up with a bona-fide purpose for which silicone is truly the best solution on a yacht, I'll be surprised to hear it (I am not talking about RTV adhesives)
 
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Likes: jon hansen
Sep 30, 2013
3,538
1988 Catalina 22 North Florida
The world simply refuses to learn about silicone. You should see the abominations I encounter in the swimming pool business. I spend many many hours removing it (mechanically). Makes me so mad I can't see straight.


EXACTLY the answer I would have given, CloudDiver. I've been doing fiberglass work since 1972 and the one absolute bane to all fiberglass repair, maintenance and construction is the whole presence of silicone sealant within about 20 yards of the boat. In my 45-odd-years of hands-on experience, as well as after having grown up with a yacht-designer engineer for a father (and first teacher), the stuff is the very worst.

Salient properties of silicone sealant:
  • Has to be mechanically removed, as you said.
  • Almost always requires remedial gelcoat work after removal.
  • Does not provide strength.
  • Does not hold out water.
  • Is always ugly; attracts mold like it's its primary purpose.
  • Interferes with every polishing and waxing job you will ever do.
  • Clogs all sandpaper rendering it worthless for anything else.
  • Soaks into raw wood just enough to bar all epoxy, sealer, paint, etc. from saturation.
  • Interferes with all other adhesion of hardware and sealing of seams.
  • Makes you look like a moronic motorboater (for some reason motorboaters seem to love the stuff; it's almost a black-white distinction-- motorboater : silicone :: sailboater : polyurethanes.

    If anyone comes up with a bona-fide purpose for which silicone is truly the best solution on a yacht, I'll be surprised to hear it (I am not talking about RTV adhesives)
 

Kermit

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Jul 31, 2010
5,657
AquaCat 12.5 17342 Wateree Lake, SC
Timely thread for me. I just received my used replacement compass today. I used a flat screwdriver to remove residual silicone residue from the back of the collar.