Misleading reference to study? 

In the section on lead paint in art (which I largely wrote), someone added the following:

"Lead paint will often become discolored over long periods of time. This is due to the reaction of the lead carbonate in the paint with traces of hydrogen sulfide in the air and with acids, often from fingerprints. [2] As a result, many older works of art that used lead paint now show some discoloration."

As I found this surprising, I went and carefully read the study being cited. Their research seemed to refer only to lead in aqueous media on paper, although that wasn't absolutely clear. But lead paint is almost never used that way! Artists working in transparent watercolor (aquarelle) don't usually use white paint, or just occasionally a bit of "Chinese White" (not lead) to make corrections. And opaque watercolors (gouache) and acrylic (polymer) artist's paints typically use titanium dioxide or (rarely) zinc white, but never lead. Normally "flake white" is used only by oil painters, and there's no indication in the study that they were referring to oil paints. Cooperstown is a well-respected institution, but as of now I'm sticking with the classic (Ralph Mayer). Flake white may get *slightly* yellowish after centuries, but nothing like the gross discoloration referred to in the paragraph above. If someone has more information on this, please mention it here; otherwise when I come back I'm going to delete that paragraph or water it down (no pun intended).