Posted by John Swensen on June 06, 2002 at 10:49:29:
In Reply to: Re: Re: Re: Re: Re: Re: Re: Hand bruising due to playing euphonium? posted by ken on June 05, 2002 at 16:16:32:
The substance is from a family of low-melt alloys, of which Cerrobend is a common trade name; Wood's metal is another name for these alloys that melt at or below the boiling point of water. The best materials don't shrink as they cool, and some actually expand a little, and most are designed to yield smoothly under stress, so they flow, rather than shattering.
The biggest problems with these alloys is that they are very expensive (around $20/pound), and many contain cadmium to get the melting temperature down. One alloy, called Cerrosafe, I believe, has no cadmium (cadmium has been linked to several health problems, and is best avoided).
Another problem with the alloys is that they can wet and bond with the metal containing them, although the same problem exists with lead (which is, also, toxic, particularly when the vapors are inhaled); my old Alex has evidence of some residual bending alloy visible inside the leadpipe.
Another alternative that has been successfully used is water; it is often mixed with a little detergent, poured into the tubing, frozen, then bent, then allowed to thaw. Reports are the ice does not protect against buckling as well as lead or other metal bending alloys, but can't be beat for ease of use. Sometimes a difficult bend can require several annealing/bending cycles to complete, and all filler material must be completely removed before heating again.