[Stoves] Sample ring from the Ring Maker - high res pic

[Lanny Henson]

Crispin,
I think you are on to something with the clay ring maker.
Can you cut holes in the rings before or after firing?
Could you stuff them with charcoal and fire them from the inside out?
Without a kiln?
Could you use low quality clay/mud rings just dry or internally fired, as an
outer stove body/module, and use a tin can liner/burner/chimney to take the
ware?
Could these rings replace a metal pail as a burner module? about 40mm od and
24-26mm id would be perfect for an 8 liter BM pot. Would they be more
insulative than a double wall metal stove?
You have a lot of good ideas and even though only 1 out of 100 good ideas is
really practical, it seems that 100 is not that many for you, go with the
creative flow!
Lanny






-----Original Message-----
From: stoves-bounces at listserv.repp.org
[mailto:stoves-bounces at listserv.repp.org]On Behalf Of Crispin
Pemberton-Pigott
Sent: Monday, July 31, 2006 8:16 PM
To: Stoves at listserv.repp.org
Subject: [Stoves] Sample ring from the Ring Maker - high res pic


See image at: http://bioenergylists.org/en/samplering

Dear Friends

I am sending you a relatively clear picture of the ring made last week here
in Swaziland.  It was formed in the ring maker from New Dawn Engineering.
The water content when formed was surprisingly high I think because of the
amount absorbed by the charcoal.

It is 2/3 clay (being itself a blend of two clays) and 1/3 pounded charcoal.
It was fired at 1000.  The clays come from the same pit, from two different
strata.  It is near Maputo.  The mix is for terracotta tiles of good
quality.

It has a nice 'ring' to it when struck sounding 'ceramic' and a density of
1.0

>From everything I can gather, it is important when firing clay with a large
amount to charcoal (or organics) in it to stay at 600 C for quite some time
to get rid of it.  Additionally, the emissions when doing so are largely CO
so it is important to ventilate the place.

There should be air flow through the kiln (typically two 1 inch holes, side
and top) to let in more oxygen.

When the carbon content is as high as this it should be held at 600 for
about 24 hours in that oxydizing atmosphere.

It seems to me one could tell if it was ready to fire to a higher
temperature by weighing it.  The chracoal should be almost entirely missing.
If it is, it can be raised to 1000 or so.  As it is insulative and the clay
is not a low thermal expansion material, the temperature rise has to be slow
in order for the middle to catch up in size with the outer skin.  It is
likely that not observing this caution will result in a greatly weakened
ring as a result of internal micro-fracturing.

Best regards from
Crispin
Matsapha
Swaziland
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