How to make an art conservator shudder: mention megilp. It was a painting medium popular in the eighteenth and nineteenth centuries. You made it by mixing a mastic resin (which comes from a Mediterranean tree that’s related to the pistachio) with linseed oil that had been boiled with a lead compound. This produced a jelly-like substance.
Painters of the time loved it because it made paint easier to work and quicker to dry and gave a rich, “buttery” quality to colours it was mixed with. An eighteenth-century writer said that it “produces that warmth and serenity which characterizes the peculiar merit of Claude Lorraine”.
The problem is that in time it turns the paint yellow or brown and makes it so brittle that it cracks. If you’ve wondered why some paintings by J M W Turner no longer have the luminous quality they reportedly had when first painted, blame megilp. For these very good reasons, nobody uses it any more.
Where the name comes from is not known; the term appears about 1760 with no clue to its origins. It’s also a rather rare surname, and some say that it may have been named after its inventor. This seems unlikely, because it has been written in many ways, including majellup and McGilp.