MITRA Forum Question Details

ApproveRejectUn-ApproveThanks for your input, Brian. I am always appreciative when Dr. Stoner chimes in as well. By the way, I coat the back of my panels with alkyd house paint, as a moisture barrier.

ApproveRejectUn-ApproveDear Koo, It is a fine idea to put tempera paintings under glass (WITH SEPARATORS so the glass does not touch the tempera surface). Andrew Wyeth sometimes used exposed white gesso as part of his composition, and sadly one of these works was in the home of a heavy smoker, so as you suggest, the hygroscopic gesso absorbed the yellow-brown cigarette tar. Also, as you say, glass prevents scratching, etc. However, it is VERY important that the framing-under-glass package allows for ventilation (as Brian suggests) because if the framed tempera goes through changing temperature and humidity conditions, especially high humidity or condensation, without ventilation, the tempera paint can mold I've seen two cases where sealing up with Marvelseal actually caused mold in a painting that had no mold previously--both happened in private homes where the environment fluctuated. Fuzzy gray mold spores are very different in appearance from the natural egg efflorescence powder or sparkles (stearic and palmitic acids) which can be brushed off readily. Putting a painting under glass does not seem to have any impact on whether the egg tempera effloresces. The Wadsworth Atheneum has three Andrew Wyeth temperas; one is under glass, one is not, and one is in a full silica gel climate control framing package. All three apparently effloresce about equally. We think efflorescence is exacerbated by the tempera undergoing changes in humidity when it is being created or is very "young." Best regards and keep painting your beautiful works. I love seeing them. Joyce Hill Stoner [P.S. please call me "Joyce"!]

ApproveRejectUn-ApproveThank you for your submission Comment: Dear Koo, It is a fine idea to put tempera paintings under glass (WITH SEPARATORS so the glass does not touch the tempera surface). Andrew Wyeth sometimes used exposed white gesso as part of his composition, and sadly one of these works was in the home of a heavy smoker, so as you suggest, the hygroscopic gesso absorbed the yellow-brown cigarette tar. Also, as you say, glass prevents scratching, etc. However, it is VERY important that the framing-under-glass package allows for ventilation (as Brian suggests) because if the framed tempera goes through changing temperature and humidity conditions, especially high humidity or condensation, without ventilation, the tempera paint can mold. I've seen two cases where sealing up with Marvelseal actually caused mold in a painting that had no mold previously--both happened in private homes where the environment fluctuated. Fuzzy gray mold spores are very different in appearance from the natural egg efflorescence powder or sparkles (stearic and palmitic acids) which can be brushed off readily. Putting a painting under glass does not seem to have any impact on whether the egg tempera effloresces. The Wadsworth Atheneum has three Andrew Wyeth temperas; one is under glass, one is not, and one is in a full silica gel climate control framing package. All three apparently effloresce about equally. We think efflorescence is exacerbated by the tempera undergoing changes in humidity when it is being created or is very "young." Best regards and keep painting your beautiful works. I love seeing them. Joyce Hill Stoner [P.S. please call me "Joyce"!]