Tips on removing silicone caulking

[cluce]

We are resealing the windows in our '79 Catalina 30. Previous owners have used a number of creative techniques to stop leaking, including silicone caulking. It is on the aluminum window frames, including the part on the inside of the boat.

I have scraped off what I can, but there are traces of it all over the place. Have used a scotchbrite pad and rubbing alcohol to try to scrub it off. Seems to work if I scrub endlessly, but I am finding that in the process it looks like I am also removing the oxidization on the aluminum as it starts to get smooth and shiny. Assume that is not a good thing, but not sure.

At the pace I am going it will be next season before the windows are done, so wondering if there are products, tips, techniques to make this easier and faster.

thx
cl

 

[Ralph Johnstone]

I've used DAP "Silicone Sealant Remover" which is just barely better than nothing. They recommend leaving on for 2 hours. We left it on for 24 hrs. with slightly better results. Eventually did get our frames clean.

No doubt about it .... silicone is a real bear to remove. Don't know if the Scotch Brite you're using is loaded with their soap but I'd be careful using it around aluminum anodizing. The scouring action along with the basic soap/detergent may compromise the anodizing.

 

[cluce]

Thanks for the reply. We tried a silicone remover and as you said, helps a bit, but not a miracle solution. Lots of scraping still.

 

[njlarry]

Have had some success with Goof Off or MEK and a razor blade scraper.

 

[centerline]

Thanks for the reply. We tried a silicone remover and as you said, helps a bit, but not a miracle solution. Lots of scraping still.

ive posted this before in other threads...

get a small stainless steel wire brush from the welding store.. or home depot and lowes carries them also in the tool section.

you can use it WITHOUT any solvents, or with solvents, your choice.... the fine brush will NOT scratch or damage the gel coat but it will quickly erode the silicone away.
and it can even be used safely on some paints, but in any case, it is way less damaging than a scotchbright pad...

because of the stainless bristles,it WILL cause a dark residue to form while scrubbing, but this can easily be wiped away with alcohol or other cleaner.

and to clean the area of any unseen silicone residue, you can use 99% rubbing alcohol to remove it, or common starting fluid (ether)....

 

[cluce]

Great, thanks. Will give that try as we still have several windows to go.

 

[centerline]

here are a couple of pics of the results around stanchion bases...

the brush also works good to remove the scum from old teak before sanding.... I scrubbed it clean, but im not going to sand it... too much work. the picture shows it a few days after scrubbing, but without oil... it was gray and and a bit mossy at the edges before I applied 3 minutes work scrubbing it clean. we still have a lot of clean up to do, but we had to get a few years worth of growth off of it so we could see where to start. it already looks so much better than it did...

 

[Jeremy_r]

The unfortunate news is that silicone caulk/sealant leaves an invisible silicone oil film behind, even after cleaning with solvents, that can severely compromise the adhesion of future compounds, including more silicone. If you have adhesion or painting problems where there was once silicone about the only guaranteed fix is to sand or otherwise abrade away the contaminated surface layer. Unfortunately that is not an option with anodized aluminum. I hope you are more lucky than some.

 

[Chief RA]

I am in the process of outfitting my boat and have effectively removed silicone down to the gelcoat. Acetone removes the residue down to the gelcoat and if a sealant will not adhere then you did not get all the silicone off. I have resealed with no real problems and that is especially true for applying new silicone. It is not easy but it CAN be done! Chief

 

[Parsons]

I've removed silicone adhesive from various plastics using non-polar solvents. I'd start with something weak like denatured alcohol, then mineral spirits, and if all else fails, acetone. Since you're working on aluminum, it's safe, but better do it outside the dock (away from your gel coat!). Working on Fiberglas, I'd probably stop at mineral spirits and give up if that didn't work. If you get a good solvent, there should be no scrubbing; paper towel only.

 

[Jeremy_r]

Results depend on the original silicone, the nature of the surface, and the type of solvent and cleaning method. Sometimes you get acceptable bonds, sometimes not. It is the subject of voluminous research/publication in the high-tech areas of aerospace bonding, paint finishes (autos and furniture), and epoxy glue bonding.

Mineral spirits and even acetone will not remove 100% of the residue but may be good enough for your needs. The residue problem is a good reason to avoid using silicones except where their benefits outweigh the big potential negative.