Using Walnut Oil to Clean and Store Oil Paint Brushes

Using Walnut Oil to Clean and Store Oil Paint Brushes
Walnut image Designed by Freepik

Back in December 2016, I talked about using oil to clean and store brushes. This post is a follow-up on how it has worked out over the last 3 months and how I have implemented it.

At some point, it I realized that I hate washing brushes and will avoid painting entirely in order not to. I decided that I needed (for my art’s sake) to find a way to wash my brushes less often. I came across a group of artist that rarely washed their brushes and instead coat them in oil to prevent them from drying out between painting sessions. For that I needed a slow drying oil. So I did some research and settled on walnut oil.

M. Graham & Co walnut oil paints

Walnut oil has been used in oil painting for ages. I even have some walnut oil paints in my stash. It’s in the family of drying oils that artists use alongside linseed, poppy and safflower. It’s a slow drying oil (faster than safflower and poppy) that doesn’t yellow as much as linseed. Making it more suitable than linseed for light colors and better than safflower and poppy in terms of dry times. It’s a popular oil among artists trying to rid themselves of solvents and M. Graham offers paints ground in walnut oil instead of linseed.

Spectrum Walnut Oil, Ingredients: 100% mechanically (expeller) pressed refined walnut oil.

There is debate over using cooking oil vs. artist oil. It is speculated that cooking oil contains preservatives that retard the drying process and is therefore unsuitable for painting. With that uncertainty in mind, I’ve decided to use cooking oil for cleaning and storage only. However, the cooking oil I bought doesn’t have any additives listed on the label. The small amounts of oil left in the brush won’t greatly effect the overall painting since it’s a drying oil and it will dry eventually. I haven’t had any issues so far with my paint not drying to the touch within a reasonable amount of time. If you’re uncomfortable with the idea of using cooking oil, just use artist oil. The choice is entirely yours.

New cleaning jar

For cleaning, I fitted a square of hardware cloth into a small glass jar and filled the jar with walnut oil to about half an inch above the hardware cloth. To clean the brush, I just brush it against the hardware cloth and wipe it on a clean paper towel, repeating as necessary. Working the brush against the side of the jar is also pretty effective. To “rinse” I dip the brush in clean oil and wipe off. The next step is to either wash with soapy water or store in clean walnut oil.

Cleaning jar after 3 months

Cleaning with oil instead of turpentine doesn’t really take any longer and is ideal for use in the winter when proper ventilation is problematic. The pigment settles  to the bottom of the jar after a while, but the oil will never be as clean as before. After I really shook up my 3 month jar, I poured it into an empty oil bottle to see how much would settle out. What you see below is after roughly a week of settling. Don’t expect it to separate as well as it would in turpentine.

Grey paint settled at the bottom after a week

To store brushes between painting sessions, get out as much pigment as possible and position the brushes, bristles down and submerged up to the ferrule, in clean walnut oil. I found a brush washer at Hobby Lobby. Before painting again, just squeeze out the oil on a paper towel. My paper towel preference is the blue ones for mechanics you find at auto parts stores. They absorb more oil than regular paper towels and are more durable for scrubbing paint off canvas.

Brush cleaner filled with clean walnut oil

This method needs to be monitored. I’ve left brushes in oil for a week several times, but a week is probably the longest I’d feel comfortable leaving it. The oil is drying, albeit slowly, and will damage your brushes if left too long.

My oil, sitting out at room temperature for the last three months, is likely rancid. I certainly wouldn’t eat it, but I think it’s fine for art purposes. Some of my paint tubes are 10 years old, making the oil in them almost certainly rancid. My paints smell the same as my cleaning oil. I describe the smell as dusty or like oil paint (obviously), which definitely smells different from a freshly opened bottle of oil, but not disgusting. This is all highly unscientific, but enough for me to be fine with it.

DIY brush holder

If you know you won’t be painting for more than a week, wash the brushes using soap and water. My previous homemade holder only held 6 brushes, which helped, but sometimes I used more or different brushes and had to wash the brushes that didn’t fit. Instructions to make the clothes pin holder are here.

The clothes pin holder can accommodate larger brushes so I’ll probably keep it around. The biggest flaw of the brush washer is that it doesn’t come in multiple sizes and the spring can only hold medium to small brushes. Large diameter brushes just pop out and you have to be careful with medium brushes.

Cheap brushes after 3 months of use

My brushes look great! I bought a pack of new cheap brushes at the beginning of my experiment so I could more clearly see any damage. The above picture is of my brushes after 3 months of hard use and almost no washings (some have never been washed). They still look new aside from paint on the handles. The bristles are holding their shape really well and there hasn’t been any paint build up near the ferrule.

I’m crossing my fingers these brushes last more than a year. I’ve needed new brushes every year for the last few years because I wear them out. Last year’s expensive brushes didn’t last any longer than cheapies. Although, worn down brushes have really come in handy for sketching on canvas and soft blending.

To use as a medium, I’d suggest using artist grade walnut oil. Because of various unknowns about cooking oil it’s a safer bet to just use artist grade oil. Although some artists report using cooking oil without issue. I couldn’t find any hard facts on the issue.

Walnut oil can be used as is to extend dry time (a little goes a very long way), sun-thickened like linseed oil to speed its dry time, and M. Graham makes a walnut alkyd that will also speed dry time. There are also several medium recipes* listed over at Wet Canvas that use walnut oil and it can be used for oiling out. I have yet to use it as a medium because I prefer to use up what I have first, but I’ve heard good things about it and intend to give it a try in the future.

*If you’re using mediums with damar varnish as an ingredient, I highly recommend cleaning your brushes with turpentine. Turpentine is the only thing that is going to break down the resin and remove it from your brushes. You’re likely using turpentine anyway in damar mixes.

The best thing about this experiment (aside from no more brush washing) is that I no longer have to use turpentine or its odorless counterparts. After not using turpentine for 3 months, I tried it last week and ran screaming from the room just to get away from it. Joking. I did have to leave the room though.

If you have any experiences using walnut oil to clean, store, or as a medium I’d love to hear.


**These are my very non-scientific findings on using walnut oil for oil painting. There was little in the way of hard facts about walnut oil in the context of art. Speculation, here-say, and anecdotes seemed to be the dominant forms of information. When I researched brush care, my findings ran the gamut from reasonable to absurd. I found something that made sense to me and fit my needs. So far, I haven’t damaged brushes or paintings (as far as I know) in my experiments.

22 thoughts on “Using Walnut Oil to Clean and Store Oil Paint Brushes”

  • “My oil, sitting out at room temperature for the last three months, is likely rancid. I certainly wouldn’t eat it, but I think it’s fine for art purposes.” – nice one.

    Thanks so much for going to such great lengths to research and experiment with all this Amber – I will certainly be taking up the walnut oil mantle in the very near future. Hopefully I’ll be able to find the sort you recommend, down here in Tasmania. And great photos by the way – this has been a nicely shot post!

    • I’m glad you found it useful! I don’t think the brand of oil really matters as long as it doesn’t have additives. And thank you, I really enjoyed taking the photos.

      • Absolutely. I broke my right hand yesterday so maybe I will take this opportunity to learn how to paint with my left hand and clean my brushes as little as possible. Perfect timing.

        • Oh no! I hope you recover soon. It’ll be interesting to see what you create with your left hand. I imagine it’ll be a looser style.

    • I haven’t started using it as a medium yet. I have a bunch of liquin I need to use up. I usually want a faster dry time so I’ll eventually try out the walnut oil alkyd.

  • Another artist told me she uses safflower oil–similar to walnut oil but less expensive. She said a granddaughter in art school told her they were doing that now. Maybe try it too? I do love the walnut oil–but have been cleaning my brushes with plain salad oil. An instructor told me to put baby oil on my sable brushes after cleaning them to keep them nice. So much to explore and experiment with.

    • That’s a good idea I may try safflower oil in the future. I don’t go through all that much oil though so I’m not super concerned with cost. I would stay away from non drying oils like your standard vegetable oil or baby oil unless you wash it out before painting. Because they don’t dry, they could really mess up a painting.

  • fabulous info! i have multiple sclerosis & have lost the function of my lifetime dominant hand. i’ve painted since the 70s [not as frequent as you] & cleaning oil painting brushes has become a problem for several years. when i could stand to brush my teeth with an electric brush [2 minute cycle, severe leg & hand fatigue], i knew i could clean my painting brushes in stages. that afternoon i painted! my usual brush cleaning procedure has been:
    -dishwashing soap dribbled on the sides or bottom of sink, brushes moved around in liquid soap. if dish soap cuts oil & grease on pots & pans, why not?!
    -cupped hand & fingers massage the brushes
    -water rinses, more soap, until no paint color appears. sometimes i let brushes soak with tips covered in dishwashing soap for hours, depends on leg fatigue & hand function. may take a day to clean.
    -before putting aside to dry, i use a dab of hair conditioner on brush tip to form pointed tip, “give body” to flat ones
    -dry on their sides, often brush tip not touching the counter [1/4″ raised lip for glass holding drying brushes]

    i am excited to try walnut oil.

    no caps makes typing with multiple sclerosis using only one finger one hand much easier

    • I can’t imagine taking a whole day to clean brushes. Hopefully this helps you speed up your process. It definitely sped up mine and no standing at the sink necessary. Good luck painting! 🙂

  • Hi! I have been using artist grade walnut oil as a medium for a couple of years now. I am painting alla prima and do a transparent under layer where the medium is walnut oil is mixed with another product called Zest-it – the fumes are supposed to be non-toxic and it smells fairly pleasant actually. In the rest of the painting, I either use the paint straight from the tube or add walnut oil only. There is less scent than linseed oil and the drying time has not been an issue. I am enjoying the method and medium!
    I was having issues with cleaning my brushes and having them splaying even though I thought I’d been careful so lately, I have been only using “The masters” brush cleaner and once the brush is clean, I leave a coating of the cleaner on the brush and shape the brush to dry that way. That has been working well so far. Your oil method sounds interesting too!

    • I’ve heard of Zest-It before, but I hadn’t realized it was suitable for use in the actual painting. I never tried it because I had trouble finding it. It’d be nice to use on the rare occasions I do wash my brushes. I don’t really have issues with my brushes splaying since they never have an opportunity to dry. No matter how careful I was when I washed my brushes after every use they always ended up splaying out after a while. Now I just wear them out and there isn’t much help for that.

      • I tried it because a teacher uses it. I do have to order it from England. Rosemary & Co. carry it. The specific product is called “oil paint dilutant and brush cleaner” bu it sounds like you have a great method worked out for yourself!

  • Thanks for the post! I usually watercolor but am taking a plunge into solvent-free oil painting. Your post will help me a lot! But I have a concern that perhaps you can clear up for me. I keep reading about the possibility of spontaneous combustion with oil soaked painting rags/paper towels. I don’t think I’ll use rags, but do you have any insight into how I should properly dispose of oiled paper towels I use after painting and cleaning? How do you dispose of your paints and trash?? Thanks so much!

    • Good question! I use the blue paper towels meant for mechanics. They’re a good cross between a paper towel and a rag. I let my rags dry then throw them out with the normal trash. You should be careful to keep the rags flat to dry and not crumpled. When a rag is crumpled, it has more surface area that can heat up. My rags are folded in half twice so they aren’t entirely flat, but I’ve never had any issues. You can tell when they’re try when they no longer look wet and get very stiff. At that point they’re safe to toss with regular trash. I never toss wet rags, but if you do, I’ve read of a lot of people disposing of turps rags by putting them in a plastic bag, filling that with water, and then disposing. I don’t see how that works in the long run since the bag is bound to burst and your rag is still soaked with a flammable substance. Better to let it dry before disposal in either case and not subject trash workers to possible fires. Empty paint tubes and dry paint scraped off palette, is the same thing. I just let it all dry out then put it in the trash. If you’re concerned with chemicals leeching into the environment, take toxic pigments/substances to to your waste collection agency and they’ll usually take that stuff for free and deal with it properly. I hope that answers your question and good luck with your oil painting.

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