[Clayart] Sea shells in the kiln?

Vince Pitelka vpitelka at dtccom.net
Sun Jan 1 08:18:51 EST 2017


Hi Ken - 
All the answers about shells are accurate, except that no one mentioned that you cannot support pots just on shells, because the shells will lose their structural integrity and collapse.  They must be filled with wadding.  For an electric firing, the wadding can just be a 50-50 mix of flint and china clay.  For salt, soda, or wood, we generally use a mix of 50 alumina, 40 china clay, and 10 ball clay.  Just pack the open side of the shell with wadding .  

Keep in mind that the only reason to do this in an electric firing would be if you specifically wanted the impression of the shell in the surface of your glaze.  The glaze conforms to the surface of the shell, and as others have mentioned, when soaked in water, the calcined shell washes away.  Around the edges of the contact surface you usually end up with sharp edges that are ground or sanded a bit to take off the sharpness.  On a wood-fired pot, those ground areas are generally not seen as a defect, but on an electric-fired pot they likely would be, and you'd have to go to considerable trouble to polish those ground area with a buffing wheel and polishing compound.  That would be a lot of work and I cannot see any advantage.  I have never heard of anyone using shells in an electric kiln, but you might come up with a situation where it is worthwhile and effective.
- Vince

Vince Pitelka
Appalachian Center for Craft
Tennessee Tech University
vpitelka at dtccom.net  
https://sites.tntech.edu/wpitelka/
 



-----Original Message-----
From: Clayart [mailto:clayart-bounces at lists.clayartworld.com] On Behalf Of Ken Chase
Sent: Saturday, December 31, 2016 5:01 PM
To: clayart at lists.clayartworld.com
Subject: [Clayart] Sea shells in the kiln?

Saw an exhibit of pottery where some of the Wares were set upon their sides on sea shells Which left an imprint. I'm a novice but I'm sure It was a wood firing or salt. Can sea shells be used in a similar fashion in an electric kiln?
And how much heat can sea shells take?
Thanks.
Ken

Sent from my iPad
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