Interesting, and very dense read. I'm really not sure how to interpret the study, though. They document changes in all of the coatings, and make note of the yellowing increasing with dammar varnish, but seem to still prefer it. At the end, though, they reach this conclusion: "For this reason, we are of the opinion that presently it is not expedient to substitute dammar for synthetic polymers (acrylates or ketones)." Is this an english as a second language issue? I read this sentence as saying that you should not be using dammar.