[TheForge] crucible furnace

[Jerry Frost]

While I can't answer your specific question, the little 
reading I did turned up a pretty efficient (Old Time) 
recipe.

Crush old unglazed, invitrified fire brick and grade 
equal amounts of 3/4" & 3/8". Cover the grog in clean 
water till no bubble rise. Measure by volume equal 
amounts of each size say one bucket of each 3/4" & 
3/8". Then you add two buckets of fireclay. Mix 
thoroughly, adding only enough water to make it stick 
about 6%. Seal it up and let it temper for several 
days.

It's then rammed into the form. 1/4" vent holes are 
drilled every foot or so from the outside about 3/4 the 
thickness of the wall to aid even drying. When it's dry 
enough to strip the form the inside is plastered with a 
similar mix with 1/4"- grog and wet enough to use like 
plaster.

After it's dried for several days a very small fire is 
lit in it and a slightly larger fire every day for 
several days before the air blast is applied. the first 
air blast fire essentially bisque (low) fires the liner 
and after it cools the liner is inspected for oversized 
cracks, spalling or other defects and patched as 
necessary. Once any patches are thoroughly dried it is 
"low" fired again with the blast.

If it takes the second firing without serious defects 
the next firing is to the high yellow to vitrify (high 
fire) the liner.

"What," you ask, "is this simple 50:50 fire clay & fire 
brick grog, recipe and rather involved process lining?"

Cupola iron melter.

Frosty
-------------------------------
If it ain't forged
it ain't real.
Wrought iron is.
The FrostWorks

Meadow Lakes, AK.

http://www.artmetalradio.com/

From: "Freddie Warner" <freddiewarner at hotmail.com>


>I used fire clay, silica sand, perlite, sawdust, for 
>my refractory. I have only melted brass and aluminum 
>and it has held up well.
> What temps can the home brew using silica sand, 
> fireclay, borax, grog stand up to?
>
> Fred
>
>