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I recently did a test with a few different mediums to see how much they yellowed by drying in the dark. Then I allowed them to receive indirect sunlight for a few weeks. I was surprised at how well the yellowing can be reversed.
Below are some swatches of titanium white and a tint of ultramarine blue mixed with common drying oils as well as alkyds. Each color swatch was mixed with a generous, but consistent amount of medium throughout. For the last row I allowed the pure medium to form a film on top of the white acrylic gesso. This test was then left to dry in complete darkness for 1.5 years; the results can be seen in the first image below. As you can see, some mediums resisted yellowing much more than others. The only inconsistent outcome was with the pure walnut oil. On it’s own, it didn’t appear to yellow at all. I think this must be an error because both the white and blue swatches containing walnut oil did in fact show yellowing. I believe it is safe to say walnut oil will not yellow as much as linseed oil, but more so than stand oil.
After I photographed the results of these tests samples left in the dark, I allowed them to sit in a north facing window sill for about 1 month where they received indirect light. Then, I photographed them once again with the same camera settings and lighting as before. The second image shows how yellowing can be reversed by exposure to sunlight. The time spent in the light really helped clear up both the paint swatches and oil films. Even the worst examples improved greatly.
Brands of Oil Mediums Used
– Utrecht Alkali Refined Linseed Oil
– M. Graham Alkali Refined Walnut Oil
– Utrecht Stand Oil
– Grumbacher Sun Thickened Linseed Oilhttp://www.kylesurges.com/
http://www.nitpickyartist.com/ - Blog and Info
Very interesting information.
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thanks for sharing your tests. On my monitor they all look yellowed, including the backgound canvas? It is a good idea to have a reference of canvas or paper included in your photo that is a pure white, then when editing the photo in a program such as gimp or picasa, you can pick that white area with the neutral color picker, and the photo will be more accurately balanced, colorwise.
Yeah, I’m having the same yellowed appearance on my iphone screen, but on my computer monitor they look fine. These images were photographed with incandescent lights and the camera’s white balance calibrated. I did very minor editing to these images in photoshop so I’m not sure why they are appearing yellow on some screens.
Are these images any better?
http://www.kylesurges.com/
http://www.nitpickyartist.com/ - Blog and Info
It was enlightening to see that the sun-thickened linseed oil yellowed less than the unworked linseed oil. The results agree with my reading wherein various experts predict generally similar results when explaining why earlier painters took such pains to continue to refine their linseed oil. Thank you for your diligence Kyle!
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My posting nick is Festus . . . but you can call me Ron . . .
I found this info interesting enough to check the Blick site for walnut oil, and it looks like M. Graham is it. I see they offer plain walnut oil and walnut oil with alkyd.
Does anyone know the percentage of each ingredient?
Would it be possible to buy their plain walnut oil and mix in my own Liquin? (I have a lot of the stuff.)
Is this a case where I could buy commercial walnut oil cheaper? Is commercial walnut oil okay, not okay . . . ???
I was impressed with Kyle’s results which seem to show walnut oil as the least yellowing of the oils. I’ve been making a simple medium of one ounce each of OMS and linseed oil with about 20 drops of Liquin, a mix that leaves most of my painting touch dry by the next day.
The walnut oil did yellow, but for some reason it didn’t seem to when allowed to dry by itself. I mentioned this in my first post.
The only inconsistent outcome was with the pure walnut oil. On it’s own, it didn’t appear to yellow at all. I think this must be an error because both the white and blue swatches containing walnut oil did in fact show yellowing. I believe it is safe to say walnut oil will not yellow as much as linseed oil, but more so than stand oil.
I’d stick with artist grade walnut oil, it’s worth the extra few bucks IMO.
http://www.kylesurges.com/
http://www.nitpickyartist.com/ - Blog and Info
Weird question…I have a rather large bottle of Gamblin refined linseed oil that is quite golden in color. Would leaving the entire bottle in the sun lighten it? I refuse to use it as is.
And my bottle of Liquin is a dark gold and I won’t use it. Time for the rubbish bin?
I’d be interested in reading the answer to the linseed oil question. I know that exposure to sunlight should result in thickening of the oil, but I don’t know about removing the golden tint.
You could try ‘washing’ the linseed oil if it’s worth the bother to you. According to Joseph Sheppard what you do is:
1. Fill a glass jar one third with water and one third with linseed oil. Then cap the jar and shake it thoroughly until the water and oil combine.
2. After a few hours three layers of liquid will be visible: the top layer is oil, the middle layer is mucilage, and the bottom layer is water. Shake it up again to remix it. You do that for twice a day for seven days.
3. After seven days you pour the mixture into a pan, let the fluids settle out again into three layers, and then put the pan into the freezer. The water and mucilage freeze but not the oil. Pour out the oil, and you have now ‘washed’ your linseed oil.
I haven’t tried this, but I might some day just to see the results.
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My posting nick is Festus . . . but you can call me Ron . . .
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