[TheForge] Ceramic chip forge

[Jerry Frost]

----- Original Message -----
From: "GHS" <ghs at execpc.com>

> The reason I said density and not refractory quality is this.
>
> In our propane or NG forges the flame is inside the kaowool or whatever
> along with the work. The object being to insulate and to heat the inside
> surface to the  glowing point  so that it radiates heat back into the
> cavity and thus to the work.
>

Yes, a reverberatory furnace to be technical.

> In a system in which the flame is in effect on the "outside", the area
> where the work is not, the object would be to heat the ceramic to the
> glowing point so that conduction and radiation would heat the work.
>

Evidently the fire is burning in the bed of chips, not outside it. Other
than that the principle is the same; heat the chips and the chips heat the
work.

> More or less the difference twixt an oven and a frying pan.
>
> I have never set lava rocks to glowing as they dissipate heat pretty
> much  as it absorbs it. A higher density ceramic should store some of
> that energy as it gets to glowing. (less surface area as it relates to
mass)
> The stored energy work be released at the point where the cooler metal
> contacted it.
>
> A glowing bed of anything should work as a forge.
>
>
> Am a missing a big part somewhere? Could be I am still on the first cup
> of coffee.
>
> Mike Graf
>
>

No I think you're as on track as I am so far.

My contention against lava for media is simply it's low melting point and
high silica content. Pumice is silicious to the point that if it hadn't been
full of disolved gasses when it cooled it'd be obsidian (volcanic glass).
Using it would essentially be trying to heat steel with clinker. Basaltic
lava is only slightly less silicious generally having a higher iron % in
part why it's much more fluid when molten and why it has a lower melting
point.

I've had lava rocks (vasicular basalt) fuse together in particularly
fearsome campfires. It wouldn't stand a chance in my forge though I may have
to fire it up and confirm it if pressed. <grin>

Melting temp aside I agree, the lower the specific heat the better for forge
media. Specific heat and density aren't the same thing. However the
distinction can be meaningless to a working device.

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

Meadow Lakes, AK.