search  current discussion  categories  glazes - cone 4-7 

cone 6 iron-red slow cool

updated sat 10 jun 00


David Malicky on wed 7 jun 00

i'm looking for a cone 6 firing schedule that will give good iron reds
(i.e., 'slow cool') but not have a bad effect on most other glazes. i
realize everything will be affected to some extent, but is there a way of
cooling that will help the iron reds develop without making everything
else more runny? (i'm using a programmable skutt kiln)

i could do some experiments but thought i would learn from others'
experience first.


David Malicky
Mechanical Engineering Department
Valparaiso University

John Post on thu 8 jun 00

At 05:27 PM 6/7/00 -0500, you wrote:
>i'm looking for a cone 6 firing schedule that will give good iron reds
>(i.e., 'slow cool') ...

Hi David,

Here is my firing schedule for cone 6 iron reds
300 degrees F per hour up to 2204 (your kiln may hit cone 6 at a different
drop at 250 degrees per hour to 1800
drop at 75 degrees per hour to 1292

The crystals in iron reds and the red color develop between 1800 and 1300
degrees f on the way down. That is why many people can get their iron reds
to look better by refiring them with a bisque load. They make the pot
spend more time in the 1800-1300 temp range this way.

If you still don't get good iron reds with the schedule, try varying the
amount of iron in the glaze. The iron needs to precipitate to the surface
while the glaze is cooling. Having enough to precipitate, but not too
much, can be a factor in what color red you get. Bone ash in the glaze
helps the red develop too. 9% is the usual amount in most of the reds I
have developed or tested.

I have fired many different iron reds using my schedule and it has worked
for all of them.

Happy testing...

John Post
Sterling Heights, Michigan USA