To seal the image, we mount the front of the photo to optically clear 95% UV-blocking acrylic. We then mount the back of the photo to a 3mm acrylic backer which seals and protects the back of the print. Lastly, unlike most acrylic facemounts which skimp on the frame, we actually use a premium hardwood frame (such as an Italian ROMA frame) on the back of the photo - this is extremely strong and straight hardwood, and it will keep the photo from bowing. If we go this much effort for the back of the image that you'll never see, then you can be sure we go to even greater extremes for the image itself. Our acrylic facemounts are archival for 120 years.