Wait, did that actually stop you from grabbing stuff you wanted or did you just get more picky? lol. Asking cause I feel like I'd end up just leaving with 0 books and a weird sense of failure instead.

Wait is this whole process really that deep for some painter's tape? I mean I get the idea but I've literally just slapped it on cold and ripped it off while the paint was still wet and it came out fine. Feels like overthinking $5 tape to me.

Yeah that "chemical clock" thing really nails it. I've heard the same thing from lab guys, they say once the latent image fades there's just nothing left to work with. It's rough though, especially when you think about the stories that were on those rolls. Your buddy must have felt sick dropping that much money and getting nothing back. Honestly that's why I tell people to just process old film as soon as you find it, even if the results are bad. At least you know for sure instead of wondering.