I have always mounted my photographs on 4 ply with a 4 ply window hinged to it. Occasionaly, if the corner gets dinged on the 4 ply mount and it's ruined unless you cut it down. Recently I have begun mounting my photos on 2 ply and attaching that to a 2 ply backer of a larger size with clear photo corners, with a 4 ply window hinged to it. The whole package is now still only 8 ply thick, but since the photograph and its mount is sandwiched inside, the corners will not get damaged as easily.
I mount my prints with photo corners to a 2ply back, and then overmat with a 4ply window mat. I then put the prints in clear plastic sleeves and stack them. There isn't a print that curls, and my humidity varies from 10-15% in the winter to as high as 90-95% in the summer.
"Often moments come looking for us". - Robert Frank
"Make good art!" - Neil Gaiman
"...the heart and mind are the true lens of the camera". - Yousuf Karsh
back slip, spacer between art care foam and print no mount just 2ply
2 ply for back of presentation matt when lightness is critical or budget of client
Yes 4ply with 4ply all the time for personal work and clients with larger budgets.
Originally Posted by PVia
Excuse my ignorance...what's a back slip? The backing/mounting board?
And you use 2 ply for the back of a presentation mat?