Silicone sealant removal

[Quetzalsailor]

I'm stuck with removing Silicone sealant from fiberglass and glass in preparation for resealing glass ports. There is much conflicting information on the 'net. You can buy solvents made for the purpose. Sika says nothing will reliably take it off except for grinding the fiberglass and replacing the port glass.

Ideas? Success stories? Failures?

Doug

[Hirilondë]

You can buy solvents made for the purpose.......... Sika says nothing will reliably take it off except for grinding the fiberglass and replacing the port glass.

Yup, but these solvent are only good at removing money from your wallet. Unfortunately I think Sika is correct. You might want to try light sanding and/or compounding instead of grinding, but definitely replace the glass. The expense of new glass is minimal compared to the frustration of using the old.

[Tim]

When will people learn that silicone is pure evil. All I can do is keep chanting and hope it somehow catches on with the unwashed masses of the boating world who may not read this forum and therefore haven't yet been informed.

Careful use of a sharp carbide scraper is reasonably effective at removing silicone from fiberglass, along with some of the gelcoat to which the silicone is indelibly adhered.

[Case]

Correct me if I am wrong but what's wrong with using good old fashioned butyl? Or dolifinite? These materials will not care about silicone (I think, I could be wrong). They rely on mechanical pressure, not from any true adhesive properties. If using dolfinite or butyl caulk, I would think that any lingering silicone (after as much removal as possible) will not matter.

I've got dolifinite on my boat (and for several windows at my house). It is still working and from what I have seen, I'm inclined to go with dolfinite once again. The dolifinite at my house held up better than the caulk that was there.

Just trying to provide a second point of view. I am not sure why people no longer use butyl or dolfinite.

- Case

[Chris Campbell]

It is possible to get rid of silicone:


All you have to do is remove the offending part from your boat. Seen here is the "after shot" of removing the silicone from the cabin top.

[bigd14]

Ahh, the Nuclear Option! I love it. Glad to see you are back to working on your boat, Chris.

[Tim]

Correct me if I am wrong but what's wrong with using good old fashioned butyl? Or dolifinite? These materials will not care about silicone (I think, I could be wrong).

Butyl and Dolfinite are both excellent materials, but I'd still not apply either over a lingering residue of silicone. Rebedding is too much of a pain to risk an insufficient seal, adhesive or not.

The real answer is to destroy every tube of silicone within striking distance of boats everywhere. so that no one will ever be tempted.

[earlylight]

I think the ultimate answer is to amputate the hands of anyone caught with a tube of silicone in their grasp.

[Rachel]

The real answer is to destroy every tube of silicone within striking distance of boats everywhere. so that no one will ever be tempted.

Yeah!

And while we're at it, let's extend that to RV's too; they seem to be another silicone magnet (why!?!).

[Quetzalsailor]

Well, as an architect, I can say that the stuff's really good for 'structural glazing'. That is, where some modernist architecture requires sheets of glass glued edge to edge and to the substrate with no metal or wood framing. I can only wonder what a building owner or restorer does next when the 50 years life expectancy is over. I should say that I am NOT a modernist architect, but a traditional one. Wood windows, wood muntins, glass and putty. Restorable.

I glued a broken piece of curved greenhouse glass back together in about 1980 and as recently as 10 years ago I understood that it's still watertight. I glued a glass chandelier finial back on about 12 years ago and that lump of glass is still hanging there (right behind me, as I type).

I've been on all the Silicone sealant manufacturer's websites looking for the info an architect would need to know to specify repairs and reglazing with this stuff. Recommended solvents vary from paint thinner, to alcohol, to acetone. Infuriating!

I think I will attempt cleaning my port glass with rubbing compound or Soft Scrub, working with buffing pads on a Mouse or Fein. I mean, if you can buff out scratches and acid graffiti on site, then you can remove the surface of the glass. I'll be sealing my ports with 1/16" EPDM foam gaskets, leaving 1/4" or so between the edge of the foam and the port opening for sealant. Pretty much as it was done 40 years ago. Belt and suspenders.

[Quetzalsailor]

Well, I did just what I said last weekend. Removing them was a bear but nothing broke. Amazingly I found huge voids under the gaskets and sealant! Recall that LeComtes have the same sort of rolled inward ports that Hinckley B-40s do and the glass is retained by an interior trim ring. Apparently, LeComte really skimped on the workmanship here! I scraped the fiberglass surface around the port, cleaned the silicone out of the voids with a burr in the Dremel and filled the voids with epoxy. I cleaned the glass with razor blade scraper. I then used Auto Body rubbing compound and lacquer thinner on the glass. I made EPDM gaskets cut back from the port opening by 1/4" (easy cut with scissors; easy purchase from McMaster Carr). I used 3M4000-UV non-structural urethane sealant. All very easy!

Then, I tried installing one...while tired and hungry. Rain was forecast for Sunday and I wanted it done. Gooped the sealant on, slapped the glass in, added the trim ring and the screws, went on deck to clean up both the sealant and the tape goo and the sealant was already skinning. Done.

Went below, gooped the next one, slapped the glass in...and it didn't fit! Apparently, LeComte was willing to fit each port to its adjoining house liner panel but not provide a perfect faying surface, and not to orient the glass so that the 'Securit' and 'safety glass' labels all faced out. Picked up the next piece of glass, added sealant...didn't fit either, but it was close enough to trim the liner a smidge, slapped it in, added the trim ring and did the cleanup but with more time spent in installation, there was more time in cleanup.

The third port was much worse since it is over some casework and behind the fireplace stack. I left it a thumb-by mess and cleaned it up today with an X-acto knife. Done, I hope. Got to the restaurant before it closed, though.

[Tom Young]

Very nice. I especially like the drift wood, our boat is full of things like that found along the way.