StudioTac
If you don’t want to use spray adhesive (messy and polluting), you can try this. It doesn’t stick quite as well, but it does a pretty good job for our purposes.
http://www.dickblick.com/products/letraset-studiotac-dry-mount-adhesives/
I buy it in single 11×17 (or so) sheets from Columbia Art Supply on Burnside.
I’ve used this to mount photos onto matte board – my problem is, in commuting, the StudioTac melted/shifted and is now on the surface of the photos. I’m trying to salvage them, but I need help! How do you clean StudioTac off the front of photos without ruining the picture?
There’s not a lot you can do, I’m afraid.
How was the piece transported (in a paper bag, box, etc)? I’m thinking in the future the method of transport will help to avoid this.