Vince Pitelka on mon 11 jan 10
Jon Byler wrote:
hate to be picky, but a reduction atmosphere can't make an oxide from
iron.
Jon -
Iron oxidizes badly at high-firing temperatures. Once that is happening,
high-fire temperatures alone will turn iron oxide to the black oxide form,
which is a powerful flux in proximity with silica. Reduction hastens the
change. This is common knowledge. A primary problem with iron in wood kiln=
s
is that oxide flakes off the surface of the metallic iron pieces and can
travel with the flame path, leaving iron spotting all over the ware. David
Hendley mentioned that he doesn't have much problem with this, and I think
it is because he is firing with an Olson fast-fired design, where the flame
travels vertically out of the firebox, dropping much of its load of ash and
other baggage before reaching the ware.
- Vince
Vince Pitelka
Appalachian Center for Craft
Tennessee Tech University
vpitelka@dtccom.net; wpitelka@tntech.edu
http://iweb.tntech.edu/wpitelka
Vince Pitelka on mon 11 jan 10
Jon Byler wrote:
I have never seen a fire get hot enough to melt iron without forced
air blowing in. the bottom of the firebox ought not to get up to the
kind of temperatures where iron or steel melts. if it does you may
also be looking at brick failure.
Hi John -
The early clay cupolas used only natural draft, and did a fine job of
melting iron. The coalbed in a wood kiln can easily reach a temperature
that will melt iron, but more importantly here, the reduction atmosphere
convert the iron to black iron oxide, a very powerful flux, and that's what
eats through the bricks. Have you ever placed a piece of iron in a cone-10
pot? It can eat right through the pot and into the kiln shelf, and that's
in the firing chamber. The coalbed of a wood kiln is far hotter than that.
- Vince
Vince Pitelka
Appalachian Center for Craft
Tennessee Tech University
vpitelka@dtccom.net; wpitelka@tntech.edu
http://iweb.tntech.edu/wpitelka
| |
|
