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bciskepottery

Member Since 28 Jun 2010
Offline Last Active Today, 09:01 PM
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Posts I've Made

In Topic: Gray Areas In Fired Glazes

14 May 2017 - 09:33 AM

I believe the cause is glaze thickness.  Some glazes are very sensitive to thickness of application, with the result being cloudiness or different color.  For those glazes that are application sensitive, the clay body or firing schedule is immaterial.  Thicker/thinner areas will appear to be different colors/shades.  Comes down to the ingredients in the glaze . . . which are uncertain here because they are commercial glazes.  Work on getting your glaze to a better application consistency so there are not overlaps or drips that cause unevenness in application. 


In Topic: Bottoms Chipping During Firing

12 May 2017 - 08:10 PM

Do I need to apply fresh kiln wash every glaze firing?

 

No, not unless you need to repair/retouch an area damaged by glaze run, etc.


In Topic: Bubbles In Black Stoneware

11 May 2017 - 02:56 PM

Gas bubbles in the 266. The glaze is maturing and sealing the surface before the gas bubbles from the clay body are released. Most common remedy is to hold top temperature during bisque to allow more of the Sulphur and other impurities to burn out. Also, stack the 266 loose in the bisque to maximize surface area to promote burnout of impurities.

Not an uncommon problem with 266 and similar clay bodies.

In Topic: Bottoms Chipping During Firing

11 May 2017 - 02:50 PM

It is called plucking, often happens with a porcelain or a porcelaineous stoneware. From your description, it sounds like you do not wax bottoms. That could be a first step. Or add some alumina hydroxide hydrate to wax -- the alumina in the wax will help keep the wares from sticking to the kiln wash. Or, use wadding.

 

Edited 5/12


In Topic: Soda Firing Techniques

09 May 2017 - 05:23 AM

Soda and salt firing atmospheres are corrosive on soft bricks like those lining your converted electric kiln, unless you have treated the bricks with some type of refractory material. And, once you go soda or salt in your kiln, it is pretty much impossible to go back to just gas firing due to soda/salt collecting on the surface of the bricks.

As you indicated you know nothing about soda firing, you would be better off finding someone with a soda or salt kiln and learning the ins/outs of firing with them and understanding soda/salt kiln design. Then build an appropriate soda kiln.