[Cob] Making a firebrick chimney thimble

[Dulane]

Sorry for the last post...

Ron,

You are probably right about the heat...else why would cob make such good 
ovens? It would be interesting to experiment with vermiculite in the clay 
tho.

And Mary Lou...that is a wonderful web site. It does have clay sleeves or 
flues. The chimney pots are wonderful!

Thank you!

http://www.superiorclay.com/products.php

----- Original Message ----- 
From: "Ron Becker" <ron45 at tularosa.net>
To: "Dulane" <silkworm at spiderhollow.com>
Sent: Monday, October 15, 2007 4:55 PM
Subject: Re: [Cob] Making a firebrick chimney thimble


| As a dabbler in primitive pottery and aquaintance of several 
| contemporary ceramics people I think firing in your stove could be 
| insufficent for the task. The clay needs to be vitrified to a certain 
| extent, I think, to handle the heat and cold swings. Besides clay is a 
| pretty good conductor of heat A F A I K. You could maybe add lots of 
| vermiculite to the clay and put some clay temperature cones from a 
| ceramics shop in your stove when you fire a trial sleve. Ceramics 
| people could tell you how hot it needed to be to use in an application 
| like that. To my way of thinking all the clay grog mixture would do is 
| delay the heat transfer for a few minutes. Wiki says fire clay has 
| oxide of silicone and aluminum. Don't know how bad those are or if they 
| get into the air during firing. All wiki said was fire clay resists 
| melting, it didn't say it does not transmit heat.
| 
| Ron
| Living and playing outside the box.
| On Oct 15, 2007, at 3:09 PM, Dulane wrote:
| 
| > I am wondering if anyone has tried using clay or fire-clay to create a
| > sleeve or thimble where the chimney meets the roof. I intend to use 
| > EPDM
| > pond liner, and I found these high-temp silicone flashing boots, but 
| > I'd
| > still like to throw a little clay up there anyway to reduce temps.
| >
| > I'm thinking of molding clay around a short piece of metal stove pipe, 
| > and
| > then firing it in my wood stove. Then I would try and get rid of the 
| > short
| > piece of stove pipe, and slide the fired clay over top of the stove 
| > pipe
| > that goes through roof and into the silicone boot.
| >
| > It may not be necessary to use the clay...as the silicone boot is 
| > supposed
| > to be high-temp, but I'm wondering about fumes etc, and I'd rather use 
| > clay
| > too.
| >
| > I've read that they used to use terra cotta sleeves and thimbles...but 
| > i
| > sure can't find them for sale on the internet.
| >
| > Any ideas?
| >
| >
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|