[Lorraine Chandler]

This is a very helpful answer. Thank you. It is going into my lampwork binder for helpful hints.

Originally Posted by Speedslug

Another thing about hoses;

Welding torch hoses are made for working with acetylene not propane.
Long use of propane in this kind of hose can cause a chemical breakdown of the rubber inside the hose and can produce a gummy substance that will spit and discolor glass as well as clog the small tube and valve surfaces in two gas torches.

Propane hoses have to be marked 'Type T' and are found in the bar-b-que section of the hardware stores.

Also the hot head torch has a small rubber part that can get old and need to be replaced.
When old and cracked it can allow propane to leak by and unburnt propane will discolor the glass.

Good luck.

ETA: Even a brand new tank can be contaminated by the place where it is filled if there is crap in the source tank it is fill/refilled from.