The mats we use are completely archival: 4-ply, acid-free and containing a white core. This means they don't come cheap, but that’s not all you pay for when you add a mat. When you add a mat you are making your entire piece larger, up to the next size. This will make your walls happier, but it also means we use more frame moulding, more plexiglass, more packaging, and more of every other material in your custom frame.
Effectively, the cost of adding a custom mat bumps you up 1 size e.g. 18x24 ($125) + Mat ($25) = 24x30 Large ($150) + No Mat.