Matt Laur , Nov 05, 2009; 11:05 a.m.
I've taken to having all of my 20x30 prints mounted to double-weight archival mat board, by the lab. It completely gets rid of the curling/buckling issue. When I go to frame it behind a facing mat board, I just cut a piece of 3/16th archival foam core the same size as the parent mat, and cut out hole the same size as the mounted print. Then, the backing board makes a sandwich, and everything stays right where it needs to be (and flat!).