I am a fused glass beginner. I have done stained glass work in the past and have some pieces of stained glass from that time. Can I use fuse pieces from one sheet of stained glass together? Is there a difference between glass for fusing and stained glass? I know about using glass of the same COE and not intermixing them. I thought using my left over stained glass (cutting pieces from one sheet) might be a good way to learn how to do some of the projects I am interested in trying.
You can (almost) always fuse a piece of glass to itself. Not all glass holds up well at fusing temperatures though — dramatic color changes (including going from transparent to opaque) and devitrification (scum forming on the surface) are not uncommon.
I have seen streaky glasses come apart after fusing — that was likely caused by the COE of one or more colors in the streaky shifting away from the rest of the glass.