Tack v.s Full The difference between a tac and full fuse is that a tac fuse maintains the shapes you originally had, just sticking them together. Whereas a full fuse melts the glass and creates one whole object, not maintaining the original shape. Also, tac fuses do not get as hot in the kiln as full fuses. Process: I made my pieces by cutting each piece individual by tracing my desired shape onto the glass with a sharpie. Once the shape was present I went ahead and cut it, then I added all of the pieces I cut together, sticking them together with glue. Once that was done I decided if I wanted a full fuse or tac fuse and had them fired.