[TheForge] crucible furnace

[terry l. ridder]

hello;

i am currently rebuilding two crucible furnaces and have the metal cut
to build an additional two crucible furnaces. the two being rebuilt have
an outside diameter of 12 inches with an inside diameter of 8 inches.
the furnace outlined in the book has an outside diameter of 13 inches
with an inside diameter of 8 inches. the 1/2 inch difference in
refractory is not that noticable. i have mixed up enough of the
homebrewed lining for the two furnaces that are being rebuilt.

the reason these two are 12 inches instead of 13 inches is that when i
built them originally i only had scrap lift truck propane cylinders
which are 12 inches in diameter.

the two new furnaces were going to have an outside diameter of 15 inches
and an inside diameter of 10 inches. these dimensions come from using
scrap 100 lb propane cylinders for the furnace body. i am considering
making these using scrap lift truck propane cylinders. i do not foresee
to use for the larger furnace.

the home brewed lining recipe from the book is;
4 gallons of silica sand
4 gallons of grog
4 gallons of fire clay
3 quarts of borax powder

i have mixed up;
10 gallons of silica sand
10 gallons of grog
10 gallons of fire clay
   8 quarts of borax powder

which is enough to reline the two furnaces being rebuilt and make a good
supply of plinths.

this mixture is currently being stored in a large plastic garage can.

before i use this home brewed lining i would like to know what other
have used to line their furnaces and what their experience has been
using that lining.

i have thought of using multiple layers of 8 lb density kaowool with a
coating of itc-100 for the furnace main body and lid. i have a complete
roll of the 8 lb density kaowool and 1 gallon of itc-100 on hand. the
bottom of the furnace body would still need to be the home brewed lining
to provide the necessary solid and rigid support for the plinth and
crucible.

-- 
terry l. ridder ><>