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View Full Version : Is it possible to remove pigment from oil used for cleaning brushes?


AnnieA
01-29-2019, 02:50 PM
This is my primary gripe about the oil method of cleaning brushes, although I manage to work around it by using a dirty oil jar for most cleaning, and a (relatively) clean oil container for those times when dirty oil could negatively affect the stroke. Despite this issue with oil, I still prefer the oil method to OMS because of personal health concerns, and although I sometimes do use a tiny bit of OMS in a small container, I know I probably should get out of that habit. The recent thread on recycling OMS gave me the idea to ask here about oil.

Oil does reasonably well in removing wet paint from brushes, but the pigment doesn't settle to the bottom of the container until it's left undisturbed for a very long time. And even when most of the pigment has settled to the bottom of the container, the oil itself still retains some color and I find this annoying.

I've tried using a coffee filter to remove the pigment, but since pigments are ground so very finely, it really doesn't work. Although I use grocery store walnut oil, which is way cheaper than artist grade, it's still expensive enough for me to hope for some way of recycling it.

So, can anyone suggest a successful method of removing pigment from cleaning oil?

Richard P
01-29-2019, 04:16 PM
Are you cleaning your brushes in the jar of oil, or dipping and wiping on paper towels?

Seaside Artist
01-30-2019, 12:27 AM
Annie...if you dip and wipe the pigments out on a paper towel, cheap toilet paper or cloth you will not have any oil in a jar and zero pigments left in your brushes. It has taken me over a year to use the last of my walnut oil (16 oz) from the grocery store. Oil can soak up into the metal via the bristles and then get into the wood handle. Before I went to this method a few years ago I had the paint peel off some of my good brush handles. More than one of my long term and well accomplished artist friends all agreed it was from leaving brushes in any liquid. Given their experiences...I decided to stop soaking and start dipping. I haven't had one brush with any problems since then. The bristles/hairs look like new. My expensive sign painting brushes when whimpy and splayed eventually from standing in oil. Dip the tip up to the paint level on the brush for 30 seconds and then wipe out the pigments on the paper...swirl the brush across the paper of choice and the pigments will come right out. 3-5 dips and swirls releases all pigments from the brush, even the darkest of pigments. I am able to change colors to use in that same brush without any further cleaning. Some have had other experiences, but that doesn't make this one wrong.

Harold Roth
01-30-2019, 06:29 AM
I read about squeezing oil out of a brush on this forum and tried it and it works much better than the coil-and-oil jar I have been using all this time. I still keep the oil in the jar but just dip the brush in and squeeze it out on a shop cloth. Only a few pigments take more than 2-3 dips and squeezes to get the brush clean.

I don't use walnut oil to clean brushes. I buy safflower oil by the gallon for that instead. It's not only cheaper, but it's thinner than walnut so I think it cleans better.

I still use d-limonene occasionally to clean dried bits off my palette.

Humbaba
01-30-2019, 08:03 AM
So, can anyone suggest a successful method of removing pigment from cleaning oil?

You could try using a centrifuge, but then the electricity bill will go up.

Making the oil less dense, to accelerate the settling of the pigments to the bottom, is another way, but you would need to remove the thinner added to the oil using distillation, or simply evaporation controlled heat (sand bath), which is time consuming and dangerous.

AnnieA
01-30-2019, 10:18 AM
Richard, Angel, Harold, I've been using a silicoil jar with the oil in it, swiping the brushes against the coil as I had previously done with OMS. I do clean them with soap and water and then Master's after a session, so they aren't saturated with oil for more than a day, and I don't leave them actually standing]/i] in oil (although I did try that for a while).

It never occurred to me [i]not to use the silicoil, somehow. The suggestion that you three made, to dip in oil without swishing and then clean the brush on a rag makes a lot of sense and I'll try that. Many, many thanks!

Humbaba, OK. I was considering the centrifuge idea, but given your caution about electricity, that's out now. :D

contumacious
01-30-2019, 11:18 AM
Try heating it in an old pan. No more dangerous than cooking french fries!

Heating lowers the viscosity allowing the solids to settle out. Look up the smoke point for the oil type you are using and keep it at least 10 degrees below that point. Use a thermometer rather than waiting for it to start smoking. Be sure to mark the pan so you don't use it for food.

Delofasht
01-30-2019, 12:20 PM
That is what I do as well contumacious.

Oil usually doesn't get much in the way of pigment in it anymore unless I am sloppy with my dipping when cleaning my brush between color changes during a painting session.

AnnieA
01-30-2019, 02:49 PM
Try heating it in an old pan. No more dangerous than cooking french fries!

Heating lowers the viscosity allowing the solids to settle out. Look up the smoke point for the oil type you are using and keep it at least 10 degrees below that point. Use a thermometer rather than waiting for it to start smoking. Be sure to mark the pan so you don't use it for food.
Hey, contumacious, I think I'll try that! (Although, since I've never made french fries, I'm not certain exactly how dangerous this might be for me!) I like using my silicoil, perhaps just because it's a long-time habit, so this might be the best answer for me. I'll have to find an old pan at a thrift store - don't want to use Cuisinart!

Delo, thanks for seconding the idea that contumacious posted.

Delofasht
01-30-2019, 03:23 PM
Okay, here is a picture of my oil not too long ago, it was worse a couple hours ago when I decided to clean it:

http://www.wetcanvas.com/Community/images/30-Jan-2019/34519-IMG_0158.jpg

And now after it's been cleaned:

http://www.wetcanvas.com/Community/images/30-Jan-2019/34519-IMG_0782.jpg

Note that the oil has become darker and more yellow, but definitely more clear, no longer cloudy, and no longer unnaturally green (phthalo + hansa pigments snuck into my oil). I took the time while the oil was cooling to clean the container as well as you might notice. The oil would not have gotten as dark if I hadn't gone away from it for about 20 minutes while it was on the heat... Someone was at the front door and I got caught up in a conversation about the previous tenants of my current house. I came back and it was actually starting to thicken up slightly, no big deal... It's just a couple ounces of oil used for cleaning.

It works nicely again, don't let your oil cook for 20 minutes, it's unnecessary, just get it up to temp and decant it immediately.

Edit: Also, I was using a double boiler; stack of 2 sauce pans, bottom half filled with water, heating the top one with just steam. This keeps the risk of it exceeding the smoke point virtually nonexistent.

AnnieA
01-31-2019, 01:08 PM
Thanks, Delo! I'm defininetly going to try the heating method for my dirty oil - what a difference!

It looks like you suspend the tips of your brushes in oil while you work, using the binder clips, right?

Pinguino
01-31-2019, 01:42 PM
Try heating it in an old pan. No more dangerous than cooking french fries!...
Maybe, maybe not. The smoke point of linseed oil or artist-grade (low oleic) safflower oil is just a little above the boiling point of water. Walnut oil is somewhat higher, but not much. The smoke point of oils used for french fries is much higher.

Should be no problem if a double-boiler method is used.

In the bad old days, someone heating food (or oil!) at the stove might get a phone call, run over to the phone on the wall, and forget about the heat. Oops.:( But nowadays, you don't have to run over to the phone; it's in your pocket. Or, you can simply turn it off.

Delofasht
01-31-2019, 02:23 PM
My brushes are always suspended in the oil like that, they stay that way for weeks, months, and the little bright has been in there for years. The green oil was actually 2 years old, used to be full to the brim, my brushes have slowly been sinking further into the cup as the oil level has dropped.

Raffless
01-31-2019, 03:05 PM
Thanks, Delo! I'm defininetly going to try the heating method for my dirty oil - what a difference!

It looks like you suspend the tips of your brushes in oil while you work, using the binder clips, right?

Annie i do something similar. But i use very small glass jars so i dont have to suspend the brushes as they only just pass the ferrule. I have seperate ones for light and darks so as not to cross contaminate.(esp white).

Delofasht
01-31-2019, 03:29 PM
Oh, that reminds me, I did manage to pick up a set of 8 little tiny glass bottles that I could arrange such that each brush could sit in their own little bottle. Only issue with that is the pressure on the bristles created by the weight of the handle pressing down and bending the bristles. It may not make much difference but then again, it might cause the bristles to become bent to one side or the other permanently.

That is why I suspend mine though, clothes pins work well for this too and are as cheap as the office clips. I actually prefer clothes pins, but always forget to grab them when I am passing a dollar store. Ah well, eventually I will get them and modify my setup.

Humbaba
02-01-2019, 07:19 AM
For those "heating" oil, consider installing a smoke-grease extractor, or do it outside, take care your home cleanliness and your health.

Delofasht
02-01-2019, 09:54 AM
For those "heating" oil, consider installing a smoke-grease extractor, or do it outside, take care your home cleanliness and your health.

That is a good suggestion, some of the pigments and other stuff in the oil may smoke even if the oil does not. I did have the exhaust fan on and the window open because it gets hot in the kitchen with the stove and oven on (was baking food at the time too).

AnnieA
02-01-2019, 12:59 PM
I think I may have a single element stove around someplace, so I could take it outside on my balcony to heat the oil, or maybe on the front concrete walkway would be even better. Thanks, everyone and especially Humbaba, who first brought up this issue.

Delo, Raffless, do your brushes become damaged by remaining in oil like that? It would seem to me they might develop some kind of stickiness around the line where the brush first comes out of the oil, and/or get oil permanently up into the ferrule. Wouldn't that cause problems?

Delofasht
02-01-2019, 01:24 PM
Delo, Raffless, do your brushes become damaged by remaining in oil like that? It would seem to me they might develop some kind of stickiness around the line where the brush first comes out of the oil, and/or get oil permanently up into the ferrule. Wouldn't that cause problems?

From my experience, that has not been an issue. To my knowledge, liquid traveling up the ferrule and causing issues only applies to water... because that causes expansion of the natural hair bristles particularly, and can seep up the bristles and past the glue. This is not true for oil, which even if it gets up in the ferrule will not cause expansion in the bristles, if anything it may contract as it dries. Which assumes it ever gets enough oxygen in the ferrule with it being submerged in oil almost all the time.

In short, many years of my bright being in oil has not caused it to splay or perform poorly... if anything, it performs better than other brushes of similar age that have received many soap, wash, and dry cycles. I have a flat of the same age that is horribly splayed by comparison, the same age as my bright. Now, that said, I have used my bright maybe ten times as much as my flat brush, so the bristles have gotten noticeably shorter than when it was new :lol: Still though, it's damage isn't a result of it's storage (and much the inverse).

EDIT: Also, I forgot, water interacts with oil more than we actually commonly think. Vegetable oils; like linseed, walnut, and poppy, do in fact expand slightly when exposed to water. So we probably have more potential to damage our brushes by washing with water. It is a necessary evil if we need to move our brushes out of oil during storage, like when doing plein air painting. At least, I have not yet developed a storage solution for this that doesn't spill or splash during traveling yet.