You can (almost) always

[Anonymous]

 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.

When in doubt, test

---

Paul
FusedGlass.Org
Helios Kiln Glass Studio
PaulTarlow.com