[Cob] Making a firebrick chimney thimble

[Dulane]

----- 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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|