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Member Since 11 Mar 2013
Offline Last Active Today, 02:25 PM

#61394 Sitter Shutting Off One Cone Before Supposed To...

Posted by earthfan on 25 June 2014 - 10:57 PM

Here is a quote from the instructions given by the manufacturer of Paragon kilns: 

"The cone used in the kiln-sitter will not react to heat in exactly the same way as a cone placed upright in the normal position. The weight of the actuation rod and the horizontal position will cause it to bend at a lower temperature than an upright cone. It is usually necessary to use one cone hotter in the kiln-sitter than the cone to which you wish to fire."

#58348 Encouraging Glaze Movement?

Posted by earthfan on 12 May 2014 - 07:03 AM

A line blend is a series of mixtures of only two ingredients. In this case, one ingredient is the mixed-up glaze without the silica, and the second ingredient is the silica. A triaxial blend is a series of mixtures of three ingredients, while a quadraxial blend is a series of mixtures of four ingredients.

There is a video on Ceramic Arts Daily of John Britt demonstrating a line blend; and another video in which he demonstrates a triaxial of three different stains. 

#58123 Encouraging Glaze Movement?

Posted by earthfan on 07 May 2014 - 10:21 PM

All my ceramic chemistry research suggests that it is alumina that stiffens the glaze. If you could replace some of the clay with silica, the glaze should move more. You would have to do many tests. I would start by mixing up and sieving a 100 gram batch with only 5% of the clay that is in the original recipe. Then create a line blend with silica. Dip a little test ring and label it, then add 4% silica. Stir it up well and dip another little test ring and label it. Repeat a couple of times. You have to remember that each time you dip the test ring, you are diminishing the quantity of glaze so adding 4% is actually adding somewhat more than 4%. But for your first firing it is very informative. In your next firing you can be more precise.