Yeah, you have to be aware of the kind of materials in the photo gear when shooting IR. I bought a Calumet 6x12 roll film holder once with the intention of using it for shooting Konica IR in it. I found out very quickly it's darkslide was not IR opaque and it's seals leaked IR in a bad way. I traded it for my Anba. Some of the older wood holders are suspect too because wood veneer is translucent to IR. Thicker wood seems to do okay. And be sure your darkroom has solid walls in that respect, a cardboard or visquine plastic blockout over a window may be merely a sheer curtain at IR frequencies. I recommend a layer of heavy duty aluminum foil over the window first if using those materials, even better is a sheetrock panel set into the windowframe.