Quote Originally Posted by colrehogan
Have you tried pointing an IR remote at a holder positioned between you and a tv set and then trying to say change channels? I know that probably sounds corny, but it might be worth a try. If it changes the channels, then it's not IR proof.
Film should be much more sensitive than an IR remote control receiver. As I recall, dark slides with five raised dots block IR. However, I couldn't verify this in a couple editions of Graphic Graflex Photography. Also, safe darkslides may be installed in unsafe film holders. Even though IR film is loaded in a darkroom, the holder is subsequently handled where there is enough IR for photography. I wouldn't trust many focusing cloths to block IR, either.