silicone the glass into the frame and add points to the back.

also this is alright for smaller pieces like 8x10 or less but larger and you need to change the glass out - picture frame gall is very thin and too weak to support the wt of GOG, even with the frame adhered, its a risk

I do this all the time. Remove the backing, print, any matting, and the glass. Lay the frame face down on a smooth level surface. Clean and dry the glass. Run a thin line of GE Silicone II Clear caulk around the edges of the frame opening (I buy this at Lowes in the 2.8 oz tube). Press the glass firmly into the cavity. If any caulk bulges out, smooth it with a popsicle stick. Let it set up well and then mosaic. You could also add glazing points but I never do.

Here is a link that might be useful: Silva's blog: WIP Bee GOG mosaic

Thank you both! It's been stopping me from getting started. I was going to make a mosaic larger than 8 x 10 so good to know about the thickness of the glass. I'll have to change that out.

yeah I'm know ppl to work bigger and then all the wt snaps the substrate glass.. best to avoid the chance

That would be awful! What if you doubled the glass? (I only ask because I have tons of glass.)

I'm not sure that would work unless you "laminated" them together

How funny that you posted this and I just now posted 5 framed mosaic's on my blog

Please check them out

http://brokenbitmosaics.blogspot.com/2014/10/the-light-catcher-mosiacs.html