removing varnish from gelcoat

[john]

previous owner of my boat was a little clumsy with varnish, and quite a bit of the stuff has gone onto the grp around the wood they varnished. What's the best way to remove this?
Thanks

 

[Guest]

Hmm, well assuming the varnish is ordinary conventional one pack varnish, i.e. NOT 2 pack poly, I'd try a cloth soaked in International Thinners No 10, i.e. the thinners for two pack varnish. This was a test done on my previously painted boat. I wanted to paint it with 2 pack but didn't know what was on it already. By soaking a cloth in 2 pack thinners, it softened the paint and it would only do that to conventional paint. You can't put 2 pack over conventional paint vv is OK though. So I would guess that by using two pack thinners it would soften the varnish enough to let you scrape it off carefully with a nice sharp scraper or chisel. Of course if No10 thinners doesn't soften it, it means it's two pack varnish, in which case I reckon you're then totally buggered, but seeing as the previous guy was a bit slapdash, I'd guess he used the cheapest varnish he could get. Your chandler's might just let you wet a cloth with the thinners before buying it as a trial 'cos it's fiendishly expensive, about a tenner for half a litre.

 

[johnt]

or there again you could dispense with the thinners..ive found that varnish comes off gelcoat easily with a new scraper blade used as flat as you can get it ..cheapy red scraper with both blade and handle touching the work and a light touch. It goes brittle and just flakes off

 

[vyv_cox]

John, we agree again!

Varnish that's a few years old is not very soluble in most solvents. Very aggressive ones like acetone will dissolve it slowly, and the GRP almost as quickly. Scraping the majority off as described by John, then rubbing with light solvent thinners, seems to be the most effective method.

Anyone got any ideas for removing it from textured melamine? I have had no success with anything, looks like the only option is to replace the melamine.