I have been considering casting blanks, heres
what i understand about this so far: for casting
pyrex blanks you need a constant temperature of approximately 2400 F, an electric heating element
which is positioned above the mold,mold material
is aluminosilicate fiber. firebrick,pyrometer,a
device which varies the current through the element. at around 2400 F pyrex has the consistancy of honey at a temp of 50 degree F
and takes a while to conform to the shape of the
mold. takes much time to anneal,days,weeks,or
months depending on diameter and thickness.
a pyrex mirror which has been cast melts at a
higher temp(over 2400F) the boron oxide reacts
chemically to lower the melting point,much as lead
combined with tin to make solder lowers the melting point of tin. anyone have idea`s/suggestions?

• RE: Any ideas on casting blanks? - bobmay - May 4, 2000 - 17:34 UTC
• RE: Any ideas on casting blanks? - Jarvis Krumbein, jkrumbein@juno.com - May 4, 2000 - 22:14 UTC
• Go For It. - crockett - May 5, 2000 - 17:59 UTC
• RE: Any ideas on casting blanks? - Bill HIgdon (willard561@aol.com) - May 30, 2000 - 14:38 UTC