| I have used scrape pieces of stained glass in my pottery pieces. It just usually melts down into a puddle on the bottom of the bowl, sometimes crazing. I don't like using it as there is no control over it. When I did it. I dipped my piece in glaze then places pieces where I more or less wanted them to go. I also have crushed the glass pieces and rolled them around in the raw clay before firing, that didn't work very well either. I thought it would melt down in a watery effect but it didn't.
It actually fell off after cooling. It would be better, I think if you know the melting temp of your glass pieces and use the same temp of your glaze/clay. I used cone 5 glaze and some pieces would melt, some wouldn't so I had slightly raised areas. Hope that helps. | 
