Whenever I printed, matted and framed my photos, they would look fantastic for a week or 2, but would always end up looking like this:
I think I’ve finally figured out how to glue and mount these properly to permanently avoid wrinkles.
With the print and cardboard cut to the same size and aligned properly, apply 3 small pieces of scotch tape on the right or left edge to create a hinge.
With newspaper or scrap cardboard placed underneath, fold open the print and cardboard and lay them picture side down.
I used to only spray the cardboard and then try to apply the print without them being hinged. One misstep or bad angle and the entire thing is ruined. The key is to press it down starting from the edge that’s hinged and then use a dowel to roll the rest of the print onto the cardboard. Make sure to pull the print up and back as you roll so that it is tight against the dowel. This method has worked every time so far.
My last few have been in a room with huge fluctuations in temperature and they still look perfect.