On the subject of removing tracker bar tubing with a heat gun,
Robbie Rhodes recently quipped:

>[ The melting temperature of solder varies widely depending upon
>[ the lead/tin alloy ratio.  Scrape a little solder from the old
>[ instrument and make a comparison test with a soldering iron.

Better yet, try melting the solder with the heat gun itself.  Not all
heat guns are equal!  This is not surprising given the variety of
applications for which they're intended.  I've frequently worked with
small, fiendishly effective heat guns whose purpose in life is to
melt solder.  Other heat guns seem to get to a mere 60 degrees C
or so.

 [ That's a hair dryer !  ;)  -- Robbie

Robbie is correct about the alloy-dependent melting temperature
of solder.  A mixture of 63% lead and 37% tin, commonly used for
electronics work, has a melting temperature below either pure tin
or pure lead.

Metallurgical regards,

Colin Hinz
Toronto, Canada