Oil Painting Mediums: Fat Versus Lean!

Darrell, I have three questions on mediums if you could help me?


Sure Betty, my answers are below your questions.

I noticed that you can mix your own medium with 20% linseed oil and 80% odorless turpentine (turpenoid?). Would you consider this a Fat medium or a Lean medium.

(This is the fattest medium you can get. One should never use over 20% linseed oil, or it takes many forevers to dry. Lean is less and less linseed oil By adding driers or additives, Cobalt or Japan driers, you can make the medium even leaner.) For commercially available mediums (pre-mixed, store-bought) I prefer the Archival Oils Lean Medium. In fact, I use this quite a bit and especially for flowers, tall ships, portraits, wildlife, still life and increasingly with landscapes and seascapes.

You should use fatter mediums if you will be spending several days working on a single painting and want to keep the paints already on the canvas soft for mixing and blending purposes.

You should use a leaner mediums when its important that your painting be painted in “stages’ and the canvas needs to dry between stages. For example, I paint portraits and wildlife in 3-4 stages. It’s important that my canvas be dry between stages. If I use a fat medium, It could take 1-3 months to complete a painting whereas with a lean medium I can complete this type of painting in 3-4 days.

Liquin in a lean medium, I think; what is Winsor Newton Glazing medium?

I do not use Liquin, but my understanding is its on the fat side taking several days for a painting to dry. Perhaps one of my students may have some input on Liquin. Generally speaking, a glazing medium is pretty lean and its frequently mixed with other materials to make it fatter. For instant, I’ve seen it used in wildlife and portrait paintings to keep paints wet. I’ve frequently used glazing medium to study its abilities for portraits and wildlife portraits, but that was primarily to use up the supply I already had. I am not a great fan of glazing mediums. I found that Glazing medium can get really lumpyt. Where I will use a glazing technique is for finishing wildlife and portraits once they’re completed and dry. While oil painting my preference is for a lean medium.

What are some other Fat mediums besides the Bob Ross’s brand?

The general rule I use is that most oil painting mediums are fat unless specifically marked lean or fast drying.

After publishing the above answers, one of my students, Goldie, added this comment.

I have both the Liquin Fine detail and the Archival Lean mediums….and if I were to compare the two I would say that the way it dries tells me that the Liquin fine detail is “fatter.” It takes almost 3 days to be touch dry whereas the Archival Lean medium dries in one day.

I have not tried the regular Liquin. I guess because I started in Acrylics I like the Archival medium the best. Funny when I do acrylics I kind of hate it when I can’t go fast enough or blend, and then in Oils I get upset when I am in marathon mode and it is not drying fast enough so I can try the next step.