 A small bundle of single-thread canes can be heated until they fuse, or heated canes, laid parallel, can be picked up on the circumference of a hot cylinder of clear or colored glass.This bundle, treated just as the chunk of color in the description above, is cased in clear glass and pulled out, forming a "vetro a fili " cane with multiple threads and perhaps a clear or solid color core.If the cane is twisted as it is pulled, the threads take a spiral shape called "vetro a retorti " (twisted glass) or "zanfirico".