picked up a roll of 3621 matte and am printing some yard signs. The print quality on this vinyl is better than on gloss, prints great in high speed mode. printed a sample, cut a peice off and put face to face and clamped together between two pieces of scrap ACM about 10 mins off the printer. Am going to do the same every couple of hours with the original sample to narrow down about how long we have to wait before mounting,cutting and stacking vertically. Will keep you posted on the results.