MITRA Forum Question Details

I cannot say that I have experienced the exact phenomenon that you describe. I have tried to always use higher quality oil paints for anything other than the most trivial color assignments. W & N does freely admit that Winton is their student line but even so, this should not be happening. I generally think of lower grades of paints having greater proportions of fillers and stabilizers that, I would think, could make the pigments less likely to sink and have a surface skin of oil, which would yellow. This could be more than offset by the lower pigmentation inherent in student grades but still this seems surprising, I wonder how you applied the thicker strokes of paint; by brush or palette knife. I have always been struck by how different the surface effects of the same paint appear when using these two different tools. This seems to go beyond the simple smooth surface left by the knife as opposed to the textured artifact of the brush but this is a bit too esoteric for the present discussion.

Anyway, I am sorry that I cannot give you answers that are more helpful. Hopefully, some of our other moderators can answer with more coherent and cogent remarks.

Finally, I would say that you should certainly paint over the offending passages with a better quality white, preferably with a highly pigmented, artist grade titanium white. This would likely mean that you would apply a more pigment rich paint over a fatter paint but it is appropriate in this case given the unsightly surface. If it were me, I would lightly abrade the surface of the offending paint with some very fine sandpaper (given that this is titanium white and not lead white or a mixture of titanium and another toxic pigments, ignore this suggestion if this is not the case). 320 or 400 grit should work. This will promote adhesion, which otherwise could have been compromised due to the slick surface skin of yellowed oil.

​I cannot speak to that, but have sent this question to Dr. Boon to see if he has any comment.