What's a firing Profile?

A firing profile is a schedule for a computer kiln to follow as it heats and cools the kiln. Most computer kilns come with pre-programmed firing schedules built into them. You can press a button for a slow bisue or a quick glaze firing. These schedules were determined by the kiln manufacturer and may not match the way you want to fire your kiln.

By reading the kiln manual while you are in front of the kiln, you can learn to program your kiln to heat up and cool down at the rates that YOU choose. Further down this page are some of the kiln firing profiles I have developed to get the results I want with my pots. None of these profiles are set in stone - I change them when I get a new idea or am looking for different results in my work.

There is no kiln that has a big red easy button that will work with every type of firing - we as potters have to learn how to control the computer to get the results we want.

I love slow cooling my pots, that's when all of the crystals and matt glazes develop their richness. I still use large pryometric cone packs in my kilns to monitor the firings and how much heat work my pots get. The computer enables me to take more control of the firing rates and make the kiln fire the way I want it to. I encourage everyone with a computerized kiln to learn to set your own firing profiles and take even more control of your work.

Electric Kiln Firing Profiles - Schedules

Cone 6 slow cool profile

 
Fire at 200° F per hour up to cone 6
Let the kiln cool on its own down to 1800° F
Then slow cool at 150° per hour down to 1300° F
When the kiln reaches 1300° F
I let it cool down on its own from there

Normal bisque profile

 
This profile is used for bone dry pots of normal thickness.
90° F per hour up to 185° F
100° F per hour up to 600° F
200° F per hour up to 1922° F
Let the kiln cool on its own

Damp ware bisque profile

 
This profile is used for pots that are past leather hard but are not bone dry
90° F per hour up to 185° F
hold at 185° F for 4 hours
100° F per hour up to 600° F
200° F per hour up to 1922° F
Let the kiln cool on its own

Thick as a brick - bisque profile

 
This profile is used for sculptures or kid made wares that are thick as a brick and would explode from the steam in a normal firing
90° F per hour up to 185° F
hold at 185° F for 8 hours
100° F per hour up to 600° F
200° F per hour up to 1922° F
Let the kiln cool on its own

Majolica Cone 1 profile

I use this profile with a cone 1 white glaze over the top of earthenware terra cotta. Then I paint Amaco cone 05 and 06 glazes over the top. Amazingly they don't run off at cone 1.
Fire at 200° F per hour up to cone 1 (2109° F in my kiln)
Then let the kiln cool on its own
This one is barely a profile but it works.
(F = Fahrenheit in all of the above profiles)


Troubleshooting iron red glazes...

I've received a fair number of e-mails from potters asking me why their attempts to reproduce my iron red glazes did not work for them. Often they tell me that their glazes turned brown instead of the reddish colors they see on my pots. The following are the things I have done to get iron reds to fire consistently red in my electric kilns. These are all of the tips I have and the only way for you to get iron reds in your kiln is for you to apply these principles.

Make Sure you Slow Cool your Kiln

 
Iron reds form as the glaze cools. I cool at 150° Fahrenheit per hour from 1800° to 1300°. Try a cooling at 125° per hour or 100° per hour if you are having trouble getting reds. Or program in a hold somewhere between 1800° and 1700° and see what happens. The only way to get my glazes to work in your kiln is to do some of the legwork for yourself. Try different firing profiles than mine if my schedule is not giving you the results you want.

Slow Cooling with a Kiln Sitter

 
After your kiln sitter drops, lift the latch slowly and press the plunger button back in. Then slowly lower the latch so that it does not trip the switch and shut off the kiln again. On kilns that have low-medium-high switches, try setting the kiln on medium for a few hours. On kilns that have a series of simple on-off switches, turn half of them off. On the manual kilns I have worked with, these strategies have created a slow cool. After a few hours of slow cooling, turn your kiln off. If your kiln looks orangey inside it is in the 1600-1800° range and that is the where iron red glazes need to spend some time.

Try a line blend

The quicker a kiln cools, the more iron a glaze needs to precipitate to the surface to create an iron red. To find out how much iron you need in your glazes, create a line blend with 0% iron red at one end, and 20% iron red at the other. I do a 10 part blend so that the glazes I get from it contain iron in amounts that increase by 2% from 0 up to 20. In my kilns with my firing schedules, I find that I get the best iron reds in the 8-12% iron range, but your kiln might fire differently than mine. Creating a line blend will help you dial in on how much iron you need in your iron red glazes.

Try different types of iron oxides

I have used Spanish iron oxide, refined red iron oxide, black iron oxide, yellow iron oxide and some wet concrete colorants from Home Depot and have achieved nice iron reds and Jen's Juicy Fruit glazes with all of them. Some potters feel strongly that the type of iron you use has a big influence on whether or not you get a nice iron red glaze. I haven't found this to be the case in my kilns. I think using line blends and finding the sweet spot in terms of the amount of iron in your glaze and working with different cooling cycles is more likely to get you moving in the right direction. But if you are still struggling and want to try something, you could try different types of iron oxides.

Clay Body Choice is Important

 
Different clay bodies react differently to iron red glazes. I get good results on Tuckers Mid-White clay body and on Rovin's RO-10 Stoneware body. Try the different clay bodies that you currently use before switching to a new one. Do line blends and vary the cooling cycles. These procedures might help you dial in on an iron red glaze and firing process that will work in your kiln.

Patience and a Willingness to Experiment

 
That's it in a nutshell. I can't fix your iron red problems in an email. The procedures above are what I used to get things dialed in with the clays I use and the kilns I fire them in. You'll have to go on the same journey to get them to work in your kiln.

Mel Jacobson's Downfiring Story






To download Mel's Downfiring Story as a pdf file click here.
To download it as a docx file click here.
To download Hank Murrow's thoughts on downfiring click here.

and here are a few Thoughts on Firing a Gas Kiln by Mel Jacobson

i have used the metaphor before that firing a kiln,
especially a gas kiln is like flying your own plane.

you know the weather, the wind direction and you
must have ample fuel.

then you have to depend on cones for the end game.

all of these factors are taken into consideration the day
before you fire.

i have a mental check list...just like a pilot. what will tomorrow
bring? should i fly, or wait for a perfect day....???

you also should consider your load. do you have glazes like shino
that need a good, solid down fire? what kind of glazes you fire will
determine what kind of firing you will have...just makes sense.
red, for sure, needs that fire up and slow cool. firing is never a guessing
game....it takes solid decisions.

if your electric kiln is poking along...well, don't fire it until you know
why. the results do not change...it will still poke along.

it is like the quote i got a few years back...`my kiln stalls at 2000F,
every time.`


i said..`how many times have you fired it with a stall`...he said...`80`.
how do you expect a better result? change things...after the first time it
stalled. do something. it took me ten minutes to determine why it stalled.
open/loose chimney, bag wall as a dam, and shelves all stuck side by side.
he changed the plan of my plan...and he wondered why it would not work.

when i fired with kurt wild we had to draw a picture of the cones as we
should see them when the kiln was done. no fighting at the end.
make the decision before you fire. makes sense. he could not abide a runny
glaze, i love them. actually group firing is hell. often no one gets
what they want. (like colleen at the `U`...no one is ever happy.) so, she uses my
kiln. then she is very happy.

so, the check list it is. have 40 cone packs ready. 9, 10, 11.
how is the gas pressure? how is the weather going to be.
how will you fire.??? are the orifices clean?? what will you fire???
it is fine craft you know...fire is the final statement about your craft.
it does define you.

mel

it always amazes me how many folks spend hundreds of hours working, fussing,
making perfect, and they throw it all in a kiln and hope some kiln god will
save their butt....(they don't work you know, it is still you in charge.
just you.)

The Sticky Image

Click here to download a copy of The “Sticky Image” process for making ceramic
decals, an ink jet embossing process By Fred Paget