Cleaning an oil painting paint transfer

Question

I recently moved a large amount of oil paintings cross country in a trailer. They were stacked vertically, but a couple of paintings that were leaning face-to-face ended up transferring paint from one to the other (see attached photos). The underlying paint seems undamaged, it seems color from one painting just transferred across. These are not fresh paintings, all were painted at least a decade ago so the paint should be completely dried and cured. Transfer happened in the past couple of days, so I'd like to take care of it hopefully before it has a chance to set.

What methods would you recommend I try to remove the transferred color?

• Water based?
• Mild detergent?
• Any mild solvents I should try?
• Gentle bristle brush work, or soft rag?

So far I haven't tried anything, this might be easy, but I'm looking for suggestions that are likely to be effective but not damage the paintings.

Answer 1

This weekend I just went ahead and tried stuff. Compressed air (40psi) plus a dry, soft toothbrush got about 60% of the extra color off. It seems that the rubbing deposited a good bit of color dust, and much of that was able to be blown off with a little agitation. I followed with a toothbrush wet with water and a drop of dish detergent. That worked moderately well. Finally, I moved to a melamine sponge (Magic Eraser) with the slightly soapy water. The melamine sponge needs some real care though. They work well around the house because 1) they are very porous and trap dirt and particles in the sponge pores, but 2) they are slightly abrasive and can remove a thin layer of paint.

My results were, on the lightning strike painting I was able to remove the extra color, but I think the white scrapes are actual damage and paint scraped from the painting (during transport not cleaning, I went really easy with the cleaning). On the fish scene, I was able to remove all the stray paint with no visible damage to the painting.