[Eddy Smiles]

Just out of curiousity what is... or what is the process going on... of the white scum that grows in the bottom of the bottle of mineral spirits that I use to rinse off my brushes that have been used to apply an oil based polyurethane product like MINWAX?

I've noticed it for a long time but never had anyone to ask about it before. If left alone it can get pretty thick. Looks like something out of a Grade "B" horror movie.

Remember now, I'm going on the theory that there's no such thing as a dumb question!

[AlArchie]

I think the scientific term is GUNK! I get the same stuff from rinsing brushes used for sanding sealer, too. However, polyurethane is a plastic, and my guess is that the thinners dilute the carrier enough to let the poly settle out, but being under a saturated solution, they can't fully cure, so just "gunk up".

I've found that if I let a can of thinner with about 1/2" or better of sludge in the bottom, evaporate, the sludge is reduced to a brittle film about 1/16" thick. It looks like very old cracked varnish.

Al

[Lynn O. Doughty]

Somebody has way too much time on his hands!! Here's the solution to the sludge problem at the bottom of the bottle.

1. Toss out the bottle and use a tin can. That way you can't see it so well.

2. Get another tin can the same size.

3. Fill one can 3/4 full of mineral spirits. Find a plastic lid to cover it.

4. When cleaning a brush, carefully pour off the mineral spirits from Can 1 into Can 2 stopping when you see the sludge. Dispose of the sludge.

5. With Can 2 now partially full of clean spirits clean your brush and, when clean, pour the remainder back into Can 1 and put the lid on.

Using this method you will hardly ever have to buy more mineral spirts.

Here is the best tip! If you do a lot of painting or staining with larger brushes, say 1" or more, go to the paint store and buy a brush spinner. It will cost you about $15 dollars but it will save you a ton of money over time. Once you clean your brush, whether in mineral spirits or water slip it into the spinner and give it a couple of pumps. It will spin out almost all the remaining cleaning agent and leave your brush soft and pliable for the next time. Also, when spinning, stick the brush in something to protect the surroundings from the stuff coming out of the brush.

[AlArchie]

Yep, Lynn, that's what I do.......two tin cans! In fact that's how I found the "sludge reduction method". Left one sludged up can open by mistake while we were gone for an extended period of time and found the reduced remnants when we returned. Not time consuming at all, just paying attention to the wierd stuff that happens all around us.

Never heard of a brush spinner, though......who handles those? Sounds like it might be worth looking into.

Al

[Lynn O. Doughty]

Brush spinners are available in most paint departments or stores. They kind of look like a old tire pump. But, believe me, they really work!

[Eddy Smiles]

There you guys go, making life complicated again.... two cans...switching back and forth. Well, I guess if it works so be it. I've simply been not sticking the brush all the way down into the sludge and when the bottle gets to the point where I can't use it anymore I trash it. It does sound like the can method is more eco-friendly!

Al... thanks for the technical explanation. I'd never though of that. mkaes sense now that you've said it.

Lynn... The next time I'm at Lowes or Home depot I'll see if they carry them. If not I know where a Sherwin Williams store is. Thanks.