How To Clean Hardened Oil Paint Brushes……Without Paint Thinner!

How To Clean Hardened Oil Paint Brushes

As much importance as I place on taking care of our painting tools and keeping our workspace tidy, sometimes a brush or two fall between the cracks and need some reviving! 

While my brush collection isn’t extensive, the brushes that I do have all serve a special purpose and so they’re each important in my set. No brush left behind! 

Unfortunately, over the holiday break a few brushes snuck away from me in my cleanup and had almost a month to fully harden… Now with oil paint, you can let a brush sit of a day or two (not ideal, but possible) but a whole month? No way!

I returned to brushes that were completely encased in cured oil paint. 

I’m not a big fan of using anything toxic in my home so I’d quicker throw these brushes out than to use paint thinner. My first step was to try soaking them in Gamblin Gamsol, which is a odorless mineral spirit used to dissolve oil paintings during the painting process. But, they were too set… Gamsol didn’t help.

I had heard about some artists soaking their dried brushes in vinegar so I thought, why not? I use vinegar in almost all my homemade cleaning products (I wrote a post all about that here!) and really, what’s the harm in trying? 

And guess what, it worked! 

Here is exactly what I did to bring my brushes back to life! 

artist holding brushes

Cleaning Dried Oil Paint Brushes – Step By Step

Not surprising to most of us, vinegar is a cleaning wizard! I use a combination of vinegar and baking soda to clean most of my kitchen and bathrooms and so I’ve seen it’s magic first hand. I had read about other artists using vinegar to clean their brushes, but what I combined vinegar and baking soda to create a better result? 

When vinegar and baking soda are combined, they undergo a chemical reaction that produces carbon dioxide gas, water, and a salt. This reaction creates fizzing and bubbling, which can help dislodge dirt and debris. While the reaction itself is not the primary cleaning mechanism, it can enhance the effectiveness of the cleaning process by providing agitation and mechanical scrubbing.

1. Soften Bristles

If you can, take your fingers and try to soften or separate some of the bristles from each other. This step is optional and sometimes impossible but some of my brushes were partially stiff so I could move them around a bit. But, don’t force it because you could risk damaging or bending the bristles beyond repair, so if it’s not easy to do, skip this step. 

2. Boil Vinegar

Using a heat proof or safe dish, boil some white vinegar and pour it into your jar or dish. Make sure the dish is big enough to fit your brushes if you have many, and also tall enough so that your brushes can sit inside the dish without falling over. 

3. Add Baking Soda

Add your brushes to the vinegar and then we’re going to slowly add the baking soda. You want the brushes inside the jar first because once you pour in the baking soda you want the brushes to be inside to benefit from the bubbling and fizzing effect between the bristles. The proportions aren’t as important but I used about 1/2 of vinegar and about 1 tablespoon of baking soda. I added it slowly to avoid a big volcanic explosion. 

4. Let Sit and Repeat

I let the brushes sit in the mixture until the vinegar cooled. Then I took the brushes out and again, using my hands softened the bristles a bit more, removing any oily crumbles. I then repeated the same hot vinegar and baking soda step and let the brushes sit in the second mixture overnight. 

5. Dish Soap Bath

In the morning, I removed the brushes and threw away the vinegar mixture. In the same jar I added hot water with some dish soap and placed my brushes inside. After about 15 min, I removed the brushes and washed them by hand with the remaining dish soap on each one. If you still have some oil paint you can use a harder cleaning brush to scrap any of that off, but I didn’t have any. I laid my brushes to dry on an old rag. 

Brushes Before and After

So I should point out that this process is not going to get you to the brand new brush state. I’ve never seen that done, but it will soften the brushes and remove the hardened paint. Depending on what type of brush you have (synthetic or real hair) this effect will vary. I found it works better with synthetic bristles.

Does Vinegar Work To Clean Dried Paint Brushes?

Ultimately yes, vinegar works to clean dried paint brushes making them good to paint with again, however it will not restore your brushes to brand new condition. Be mindful that this is a natural cleaning process and if you’re looking for that really heavy duty cleaning you’ll probably need to use paint thinner.

To be honest though, I’ve never tried to use paint thinner as I really don’t like the toxicity of these products so I can’t truthfully say how much better paint thinner would have performed.

Hope this works for you as well as it did for me!




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