MITRA Forum Question Details

The problem is likely that your paint is too fat (too much greasiness/oil as compared to pigment load), too thinned with solvent (which immediately facilitates the accumulation of surplus oil at the surface of the paint}, or a combination of the two. There should no super-surplus of oil at the surface of any application of oil paint. Having less yellowing, but poorer paint film formers, like poppy seed oil oozing to the surface does not solve the problem, but just makes a lateral move to another issues.

On an unrelated, but tangentially related issue,  I have applied the same paint, without additional medium, using a brush and a palette knife and the paint applied with the knife is both glossier but also greasier than that applied with a brush. I have also seen yellowing associated with knife applied paints where none was observed with the brush applied films. None of this was scientific and I would not swear in court, but I think that there is far more going on in terms of physics and rheology with paint manipulation that we might intuitively think.

This may seem tangential, but I remember that when I worked with Dr. Leslie Carlyle, she observed what appeared to be transparent, seemingly intentionally applied interlayers between layers of paint and a smooth mylar substrate. We knew that no transparent, unpigmented layer could have been applied because we made and scrupulously documented the stratigraphy of those layers. It appears that the smoothness of the mylar substrate influenced the accumulation of binding media creating the appearance of an applied unpigmented interlayer.

This is not directly related to the discussion at hand, but it does speak to the idea that media can accumulate at the interface between certain physical phenomenon.

I totally agree, but remember that in the situation that I quote about the cross-sections taken from the Carlyle research, the faux interlayer is below the paint layer and not at the top. Clearly there is more going than settling in this instance, and more complicated physical dynamics are going on.