About four years ago I was in the Basilica of saint Francis of Assis and there were a number of what appeared to be friar guides using laser lights to direct their groups eyes around the murals high above them. Could this be damaging to the pigments in the paintings? Hindsight is 2020, but instead of asking them directly I went to a guard and asked if they should be doing this. “I understand but it’s out of my control.”
Were my concerns valid ones? I’ve since noticed it being done, if more briefly, on stained glass windows in the Chartres Cathedral as well.
Thank you to you both for replying to my question, and I’m reassured by the answers.
I am inclined to think that the low powered laser used in pointers would do little damage but honestly, I am not sure and we all know the danger in assuming.
I have sent this along to our representatives in preventive conservation in the hopes of a more thoughtful answer.
Great question! Laser pointers emit light from a very narrow band of the electromagnetic spectrum, which gives them their color. Green laser pointers are of a higher energy level than red ones, but neither emits UV radiation, which is the most damaging for painted surfaces. They do produce some heat, which could cause damage if the laser was pointed in the same spot for an extended period of time. In this case, however, I don’t think the exposure time would be long enough to result in damage.
Madeline Cooper
WUDPAC 2021 Preventive Conservation Major
