Square picture frames are a very attractive format for framing. Obviously photographs or artworks need to be square!
Your picture framer however should add an extra 5 mil to the mount at bottom of the picture. This is common procedure for two reasons.
- Framing needs to have wriggle-room to allow the glass and artworks to be put in and out of the frame with ease. To ensure this the framer will always make the frame a few mil bigger than the sandwich of glass, mountcard and backing board. If they didn’t then it would be impossible to fit into the frame let alone to take out again. This is where imprecision works to the framers advantage. So what happens then is the mount sits on the bottom rebate. The rebate might be 5 mil in depth. If the mount is exactly square visually you are removing 5 mil from the bottom and this will result in the mount looking smaller on the bottom than on the top.
- The second reason is an optical trick reason. Even if the mount were to be cut perfectly to fit the frame with no wriggle-room it would still appear that the bottom mount width would look less deep. An unsettling feeling that the picture and framer are top heavy and falling forward.
To counter these two effects picture framers always add 5 mill to the bottom of a picture however small and even more when the artwork is larger in size.