spar urethane cleanup

[BillZ]

For best results, I learned to use a high quality brush when applying polycrylic but I am afraid of ruining the expensive brush with spar urethane. Last weekend I did some spot finishing on the woody tear where it was wearing thin.I used a disposable foam applicator and really didn't like the results. The one time I used a brush with spar I put it in a cup of mineral spirits and swished it around a while. Ugh I hate that stuff! It still dried hard and the brush was ruined. Do I need to use gloved hands and really douse it with a ton of cleaner? What is the proper way to care for a good brush that is used for oil based finishes?

[48Rob]

Bill,

Mineral spirits.

Just "swishing it around awhile" isn't enough, I do so 3-5 times, emptying the cup and putting new mineral spirits in until it runs clear.
There is a new "green" mineral spirits out now that works just as well, but doesn't stink.

I have several varnish and oil paint brushes that are many years old, cleaned each time with mineral spirits.

Perhaps in addition to not cleaning them well enough, you are waiting too long to clean them?
I wouldn't want to use a varnish brush any longer than an hour before cleaning it, as the material will begin to set up and then it is near impossible to clean out of the brush.

Rob

[parnold]

I used an acetone based paint thinner to clean my brush. I did not feel the need to dump and refresh the thinner, but I did only use each batch once. After vigorous swooshing, mushing, mashing, etc, I used newspaper to get the brush as dry as possible. I used the brush probably 8 times over the course of my first build, and it is still in near perfect condition.

[Dean in Ct.]

There is a device for spinning a paint brush clean and it also can be used on rollers. I use kerosene almost exclusively. Spin it in the kero then spin it out of the kero (in a trash can or some container). Give a few passes then, and this is the important part, soap and water. I use a little dish soap in the palm of my hand. Then I give a final spin to dry it and hang it on a nail. Works well for me!
Good luck!

[VijayGupta]

Here's the method(s) I use for any oil-based varnish:

First prime the brush by dipping it in mineral spirits. This will fill the top of the bristles near the ferrule (the metal part) so the varnish does not wick up there as much.

Once done varnishing I use the "two-can" method:
- Wipe excess varnish off the brush with a dry rag
- Can #1 contains mineral spirits that has been previously used for brush cleaning. Dip the brush in and swish it around. If you have nitrile gloves, you can massage the bristles.
- Wipe off with a dry rag
- Can #2 contains cleaner mineral spirits. Likewise, dip, swish, and wipe.
[at this point, you can enlist a can #3 with even cleaner MS, or just skip ahead]
Now you have a mostly clean brush with oily mineral spirits.

Either
- Swish the brush in a can of lacquer thinner or acetone, shake off excess and wipe dry.
or
- Wash the brush with Dawn and water, rinsing thoroughly, wipe dry.

Then put the brush in a jacket or wrap in grocery bag (Kraft paper) to dry.

Eventually can #1 will become too cruddy to use. Either set outside to dry, then discard, or decant off the clear top stuff into can #2. Promote can #2 to be new can #1 and put clean MS in a new can to start new can #2 (or can #3 if you are using the three-can variant).


Despite best efforts, your brushes may get build-up over time. Then you have two options:
- Buy a can of "Brush cleaner" and allow to soak brushes overnight in this. These are about every stripper and solvent for paint, in one one soup.
- Soak your brush overnight in NMP-based paint stripper. Rinse out the next day with soap and water.

You can reuse either of the above solutions until they loose effectiveness.