MTFCA Forum

I found a post on this forum a couple of years ago about applying thinned Spar varnish to the firewall with a cloth, and it worked great. I want to do it again for another car but I can't remember if it should be a 50/50 percentage or something else. Also, I can't remember if I used turpentine or mineral spirits the first time. Recommendations welcome!

Hi Frank, I would suggest using the thinners given on the varnish tin as different manufacturers can use different bases. Try the thinning ratio on a bit of scrap wood and see what works for you.
Cheers

See this post as well: https://www.mtfca.com/discus/messages/1 ... 69404.html
and this one: https://www.mtfca.com/phpBB3/viewtopic.php?t=23013

Penetrol is a product made to thin paints and extend brushing time to allow even coating. You just need to check that it is compatible with the product you want to use.

Allan from down under.

What Allan said. Urethane varnishes don’t thin well and are best used at package consistency. They don’t behave like the natural resin long oil varnishes of yore. Any road, a new-fangled foam brush would be a far better applicator than a rag.

Thanks to everyone who responded to my question about using Spar varnish. Much appreciated!