Been trying to dig up posts and articles on this again. I have quite a few Rollei IR sheets left and while I don't like it's thin base, I'm thinking of giving it another try in LF. I've had good success with it in 120 (using ISO 3 and 6 with an R72 filer as I recall) but never any in 4x5. I started my 4x5 IR journey on an Intrepid MK2 but now also have a Chamonix 45F2. The former has a light leak I need to sort out (and I'm not sure how IR safe it is) and the latter is known for not having IR safe bellows.

Without having to go out and buy bellows (Shan Hao's apparently are IR safe?) I was thinking of using reflective mylar. The Evil Jungle has a number of these but the ones that specifically say IR safe are as much as just buying IR bellows. It seems anything with aluminium should be safe correct? Including the stuff used for plant growth applications as well as one of those emergency blankets?

Also do I need to load the sheets differently? E.g. wondering if my darkroom might be somehow fogging the film and maybe I should use the mylar while loading as well? Do film holders make a difference?

Any thoughts or ideas?