I know there are many styles of painting frames out there, is there a "best" one? And what are the various usage techniques of them?
Thats a great question, few days ago I asked something similar but got put "on hold".
The answer for my question at least was that there is a ridge in the inside frame where the glass cover can sit, and the art piece will be placed behind it. In turn, behind the art piece, a carboard or something solid will be placed to hold it in place. Now, because it is an older frame, the only way to secure the glass, art, and backing all together will be to drive small nails into the frame, bend them, and use them as stoppers.
Hope it helps.