Lots of questions there - I'll try to answer all.

First of all, what about the backside is "horrible?" Can you be more specific? Is it grout bleed that makes it look bad to you?

I use Weldbond on my windows. It eventually dries clear - sometimes takes weeks or months if the glass piece is big and the the glue thick. I've learned to get around this by gluing only the outside edges of larger glass pieces. This way they dry clear faster and there is less chance of grout bleed underneath. Weldbond on the top of glass comes off when grouting (mostly). Otherwise I go at the finished piece with razor blades and exacto knives.

I use the cheapest black grout I can find (American Adhesives, I believe)- dry (I mix with water and mix it VERY stiff). Too runny grout can encourage grout bleed.

How do I work? It varies on each window but I DO work horizontally - not vertically. I spread the window over two chairs backs which brings it to about the right work height for short little me. Sometimes I work a lot at once and sometimes I inch forward . . depends on the piece. Working horizontally means I can walk away at any time.

I have tried Mac glue and like it's transparency a little better than Weldbond, but (and this is a BIG but) I don't think I'd use it on gog windows because of the way I work. Sometimes I'll lay down a patch of glue and start placing pieces in it. Invariably I get interrupted and have to walk away. If the glue is weldbond I can scrape it off and start over. NOT SO with Mac. It's PERMANENT and thus anything I lay over that dried Mac Glue is now "lumpy" and not in line with the rest of the work.

Wipe my fingers? Good God no. If I had to be tidy I'd take up another calling. I usually have glue on everything and have been known to walk through the house trying to shake off the snippets of things that have dried on my hands . . .

Can you post a photo of your "horrible" piece? Grout bleed can be fixed with a little ingenuity . . .

Did I answer them all?

Thanks so much for answering my questions. I think I may have discovered part of the problem. The grout has seeped-alot! I had done another vase and there was no grout bleed at all. So, I had it in my head that it was easy to do gog. (That's what happens when you get cocky.) Your comment on using dry grout-I think that was it! The first time I used a very dry mixture of grout and it was really easy. When i did the second one, the grout was mushy because the spaces were smaller and I thought, apparently incorrectly, that it needed to be wetter.

I've never used welbond, but will look into that 'cause I am not liking the clean up I must do with the silicone on these indoor projects.

Left my camera in hubby's car and he's out of town on business. I can post a pic by Monday morning.

Thanks again for sharing your insight!

Here are pics of the vase I did that seemed pretty good on the inside. (the white/brown vase) Then the pics of the black vase that has a lot of seepage. In my opinion, there are other issue with this vase too, but the seepage is the worst part.

BTW, I had trouble getting the remnants of the silicone off of the glass. I scraped, I rubbed, I did everything I could to get it off the top of the glass but had no luck getting it off. (Some of the glass had LOTS of texture.) There was still some residue, not globs of silicone, just yucky residue that kept the glass from shining up and buffing nicely. I tried vinegar and regular glass cleaner too. Anyway, I used something called goof off on the glass. Then to clean the goof off, off, I used regular dish detergent and it shined up really nice. Not sure what chemical reaction might happen in the future to tear it up, but right now it looks pretty good.

I just noticed that the brown/white vase has grout residue powder on the inside, that's the white dust you see in the pic. Didn't really notice it until I previewed the pics.

Here is a link that might be useful:

Looks like seepage is your problem. Mix your grout dryer for GOG and try more silicone cleanup before your grout. I use an exacto or straight razor blade and go over every inch of the piece before grouting (that doesn't mean I don't miss some cuz there's always cleanup afterward).

Best of luck in future endeavors!