I now have this issue with Breathing Color Chromata going slack. At first I thought it was a one off, I had a customer call back saying a large three piece had ripples running throught it. My canvas prints are edge glued around the edges and back, and I've been using this technique for a few years with no issues.
I took it back and restretched it. At the same time I redid one of the prints after it got damaged pulling it off. With the new print I mounted it, and dropped the whole lot off. The customer then called back to say the one I'd redone had gone slack too! Anyway I fixed it up, only needing a 2mm or so adjustment. These were around 30 x 24 inch size, but I've noticed some 18 x 20 and A3 sizes do the same thing before delivery, and now a large 1800mm x 600mm is showing the same signs. These are stretched quite tight, then the slackening starts to appear. It's winter down in NZ and reasonably cold but this has never been an issue in previous years. I'm waiting to hear back from supplier and talk to him about this. I hope it's just something wrong I'm doing...what, I don't know...
Neal
Quick update - got a call back from my supplier - a good bloke to deal with. He reports no issues from the main printers whom use his rolls. I may well be looking at temperature/humidity issues in my house where I print/coat (Glamour II) and mount.