Poly/Mineral Spirits Question

[Dave Dye]

I cut my Polyl with Mineral Spirits. I normally have some left over a pour it back in the can. Does this thin whats in the can, or does is dissipate over time?

Thanks

[Steve Schoene]

If you put the lid on the can it certainly thins the entire contents.

[Dave Dye]

Thanks Steve, I thought that would be the case, just wanted to check. Don't want the container to get too thin.

[Howard Acheson]

Dave, it's a poor idea to attempt to save thinned varnish by putting back in a can will un-thinned varnish. It tends to contaminate the varnish with any dust or other gunk it has picked up. As the thinned varnish has been exposed to oxygen for an extended period, it has started to cure whether you can see it or not. Therefore it's going to shorten the shelf life of the unused varnish.

Either store is separately, or better, discard it if you do not have a use for it in a couple of days.