On Sun, 21 Oct 2007 00:33:17 GMT, "Harold and Susan Vordos"
wrote:

Slight variations in density are
likely due to the degree of fusion. Dunno! :-)

That's more or less the situtation with the density. Fine tungsten
powder is pressed into bars. The bars are resistance heated (imagine a
rod the size of your thumb glowing at 4800F!) to sinter the powder.
The bars shrink and get denser as the tungsten crystallizes. Swaging,
rolling, and drawing increase the density and deform the crystals,
yielding the typical fibrous structure.

Lamp filaments run hot enough that the tungsten recrystallizes, which
is why a filament is more fragile once it's burned for a while.

--
Ned Simmons