It's great stuff to work with Bonnie.
You can either paint the back of the glass(before you break it) or paint your substrate.
I have used Weldbond to secure, none of the pieces I have used it for were for outdoors.
The frog was done by a friend of mine that I taught for awhile. This is ungrouted. We also did one we painted spots on. The spots on this one are the painted glass.
We did some ceramic fruit!
It works well on candle hurricanes. You can barely see the colored pieces in it.
The final picture is of one of my favorite crosses.
It is also great to fill up large spaces between tesse stuff.
Hope this helps.
I think I may have to go find those buckets of glass I have!

LA - I had to go waaaaaaaay back to find a couple of things I mosaiced w/TG. You can glue shiny foil, photos, leaves, whatever to your base, then glue the glass over it. As TX says, you can either paint the glass or the base also. I found Weldbond to be too slow to dry, so ended up using silicon. There are two boxes using Weldbond, and silicon. There's also a little mirror w/a red heart in the corner in my "mirror" album where I used gold glitter glue to adhere the pieces. Waaaay down in "My Queendom" album is a picture showing size of the glass pieces. Try to keep them from breaking into teensy pieces. It's very addictive to work with this stuff.

did you paint the cross or the glass in this case? And it looks like you didn't use any grout? (I've always used grout but love the effect on your cross)