there are little keepers u can buy from a hardware store or woodworking store or even a picture framing shop. all u do is screw them in the wood and then u can turn them to keep the pic in or turn them to take the pic out. there called turn buttons i looked them up on the rockler site. if u click the like u can see what they look like.

http://i855.photobucket.com/albums/ab120/icomba/27912a-md.jpg

 

DaveR: Yeah, I kind of realized my mistake with the rabbet after it was already too late. I'll make it deeper next time. The painting is a bit unusual as it is on the back of a fake brick-patterned vinyl panel material, since my Uncle (the painter) worked in a lumber yard with lots of odd scrap. Thus, the depth is rather uneven on the back. I like your suggestion of mending plates… installing those on the corners, maybe with some foam underneath to account for the odd painting material, should hold it well. I'll pick some up tomorrow and give it a try. Thanks for the advice.

 

bigike: Those button things look like they'd work well too… I'll see what the store carries tomorrow.

 

In my opinion (you know what they say about opinions) I would like to add a second frame to the back, just a mitered, non rabetted piece to add to the depth of the frame. That way there would be adequate depth to fasten the painting with small brads or anything you wish.
I've framed many paintings. Many ready made picture frame mouldings have insufficient depth and when forced to use them I give them the depth needed with added plain moulding as mentioned.
The edges of this added material would need to be finished as they would be visible from the side.
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