Comment

Comment by Brent Farler on September 4, 2013 at 9:06am

Zena,

For your bisque fire you might blow a few pots up.  There are two critical points during bisque firing. The first when your pots cross the boiling point of water and the free water in the clay turns to steam when the pot hits 212 (your kiln may be hotter than that).

The second occurs in the 1100-1200 degree range when water chemically bonded in the clay is released.  You see it as water vapor escaping your vent holes if you hold a room temp mirror over the vent for a few seconds. 

For the lower temp a hold and slow warm up usually covers this.  For the higher temp I always keep my kiln at medium at least until this point is passed.

For glaze firing speed, time at temperature and cooling rate has all kinds of impacts on glazes and their ability to let gases escape from clay, heal the pinholes and bubbles, form crystals and colors.  Suffice it to say that you can vary your results quite a bit just by changing the speed up and down.  Lot's of good posts in these forums.

Comment by Tracy Shea on September 4, 2013 at 7:58am

Faster speed with faster cool might gloss up your mattes if you are using them. My real advice is, since you are just learning, is to try it. That's how you will learn what your kiln will do with that firing schedule.  Good luck! 

Comment by Zena E Forte on September 3, 2013 at 7:52am

i usually fire my cone 6 glaze stoneware at medium speed. what will happen if i use fast speed? Using a programmable controller.

Comment by Carole Evans on November 20, 2012 at 11:55am

I just read a comment by Patti Goldstein (from back on 11-2-11) regarding Laguna clays (including #50 & #60).  I've primarily used these exact clay bodies for the past 14 years.  Does anyone have any further information as to the safety of using these in the raw state in your studio?  My concern is that my studio is in my basement where ventilation isn't the best.  I do take great care to keep dust to a minimum and the exhaust fan on my kiln is strong (to the point where I have pulling problems with pieces placed near the intake hole for a glaze firing.)  Very frustrating . . . but I digress.   

Comment by Mary Jane on August 26, 2012 at 12:36pm

Hi - I just did a test tile with Val Cushings turquoise at cone 5/6 on b-mix and I love the color.  Wanted to know if it is food safe for sure.  I am really asking because turquoise glazes I have seen in the past have not been food safe - but this one is glossy in my kiln and seems low enough in copper to be fine.  Any help is appreciated.  Thx, MJ

Here is the recipe that I used.

Dolomite    3.7

Gerstley Borate   21.8

Silica     27.5

Feldspar - Custer   35.6

Whiting    11.4

 

Copper Carb     3.0

bentonite          1.0

 

 

Comment by Allyce Capps on November 5, 2011 at 9:40pm

I have used a speckled standard clay for years and haven't had any ill effects. I assume that it burns out as firing so the fumes could be an issue without good ventilation.