Quote Originally Posted by Tom Taylor View Post
I’m not saying that projection doesn’t do some harm to transparencies but I have often left slides (35mm, 645, and 6x7) up on the screen for several – 10 or even 20 minutes at a time - without any noticeable effect. Projectors have a fan to whisk heat away from the film. I wouldn’t worry about it too much.

Agree. A good projector puts very little heat on the slide because of the fan. My Dad and his friends used to leave a slide up for a long time while they were discussing the qualities of it. Those old slides still look great!

He used a Golde projector, and I have a couple of Aeroquips, and neither one seems to heat the slide much.