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I used a brush to apply polyurethane on some trim work. I tried cleaning it thoroughly with paint thinner after but still got poor results--the brush bristles would stick together and the brush was unusable. I also heard mineral spirits and acetone may work. Should I try something else or are brushes pretty much done after a single use?

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  • dynasolve or xylene are the cleaners i use for cleaning my tools
    – user61623
    Commented Oct 21, 2016 at 10:59

9 Answers 9

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I have had trouble cleaning them with everything and had the same problem, until I found a jar large enough to put the brush in filled to the bristle level with thinner keeping it tightly sealed. (I do clean them prior to putting in the jar). When I need them take out shake dry and they work like new brushes for months without being used or when I have a project that gets a new coat every day for a week. (I find the higher quality brushes provide the best coverage so I hate to toss them with just 1 use)

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  • If you don't need it soon, how long do you keep it in ?
    – amphibient
    Commented Dec 4, 2015 at 1:21
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    I have had them in the jar for over 6 months. The thinner has not affected them that I can tell. My wide brush is ~3 years old the narrow ones maybe 2 years old.(I only take them out to use them now)
    – Ed Beal
    Commented Dec 4, 2015 at 14:12
  • that worked really, really well, thanks. I just kept three brushes in a can overnight, much better.
    – amphibient
    Commented Dec 5, 2015 at 0:10
  • You said "(I do clean them prior to putting in the jar)". What does that mean? How do you clean them prior to storage? Commented Jul 8, 2017 at 22:28
  • By cleaning before I usually squeeze the majority of the paint or other poly solids out of the brush then 1 rince to remove the majority of the solids th3n put the brush in bristles deep thinner and seal it. With poly that I may be continuing work within a week I may not clear as much but keep the bristles in thinner. Shake the excess thinner out and the brush is ready for another coat.
    – Ed Beal
    Commented Jul 9, 2017 at 20:32
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I make picture frames and I like polyurethane because it is a very hard, durable finish. I always use foam brushes. To clean I merely soak in paint thinner a short time shake it out and dry with a paper towel. You can do this over and over if you want. But at around twenty five cent for a brush you could just toss them. And they leave a nice even coat as well.

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  • Hello, and welcome to Home Improvement. Thanks for the answer; keep 'em coming. And, you should probably take our tour so you'll know how best to contribute here. Commented Jun 26, 2019 at 13:21
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since there are water based polyurethanes that you can clean up with water, you can use those. however, start with a good quality brush. if you want to use an alkyd, clean (thoroughly - not just a dunk) with paint thinner (takes the paint into solution and flushes it away), then with acetone (takes the thinner into solution and flushes it away), then with water (takes the acetone into solution and flushes it away as well as acting as a solvent for the soap). then rub the bristles in hand bar soap (i like ivory hand soap for this). the brush will stay nice and soft and supple. when you want to use it again, just quickly dunk it in whatever solvent is the solvent in whatever paint you want to use. you can keep a quality brush going for years with this approach.

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I've done all of the above - But I read that putting a little clothes softener in with the paint thinner also keeps the bristles very soft ! I have tried this and it does work !

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$14 Purdy or Wooster brushes are trash after applying poly. Use cheaper disposable foam applicators.

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Maybe not politically correct but I found a quick dunk & swoosh in gasoline works better then any paint thinner or solvent. After dunking, I squeeze out what I can by hand & then apply liquid dish soap (like dawn) & work into the bristles to remove the gas. Rinse in hot water & allow to dry. I find that placing a rubber band on it helps to keep shape.

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  • What does that have to do with political correctness?
    – amphibient
    Commented Mar 27, 2021 at 16:49
  • @amphibient gasoline isn't a good choice for a solvent due to the hazards involved (the flashpoint is awful low, for one) Commented Mar 27, 2021 at 17:04
  • If you're going to do this, do this OUTSIDE and AWAY from potential ignition sources. Gasoline's flashpoint is well into the negatives, and the vapors are "have passport, will travel to ignition source below you!" Commented Mar 27, 2021 at 17:05
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I used paint stripper followed by soap and water and it worked well. A bristle comb helps (for paint brushes).

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Anyone try putting the brush in the freezer after you rinse with paint thinner? My grandpa use to tell me this worked.

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After applying polyurethane finish I use paint thinner to clean my brushes and have never ruined one. I put about 3/4" of thinner in an old medium sized pot I requisitioned from the kitchen and fan the brush back and forth on the bottom. If you're using something like Minwax Polyshades the thinner will become cloudy from the stain in the poly (if using clear finish clean your brush for a couple minutes each stage of cleaning). Shake the thinner out of the brush and repeat with fresh thinner. Put the cloudy thinner in a jar to settle the solids out for future use as a first rinse. After cleaning your brush the second time shake the brush out again. The thinner will still be slightly cloudy so put it in another jar. Now rinse the brush one more time in clean thinner, shake it out and put it back in the brush cover. It may feel slightly stiff when you get it out the next time but just fan it out and it will work and feel as good as new. Been using this technique for many years and still using brushes some might consider to be antique.

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