Tuesday, June 2, 2009

Facing Your Fears

bottom shelf after firing

First of all I want to thank everyone who gave me support on my blog and by email while I was firing my kiln. All of your advice is so helpful and I truly appreciate each and everyone who gives advice. If you are a reader of my blog and have never commented, please don't be shy, just chime in with any and all advice or comments. I learn something from everyone who comments here, and I also learn something from every blog I read and comment on. Be sure to read the next to the last paragraph of this post to read an example of one thing I learned from another blog.

my Skutt kiln

After I posted about being scared to fire my kiln for the first time, I was feeling kind of sheepish. I almost deleted the post. But then I thought, no, someone else may be feeling the same as I did, afraid to fire their kiln and my post may help them in some way. I think my fear stemmed from the fact there is electricity involved. To me fire isn't so scary, electricity is. I also had a bit of a fear of failure, of having a problem with the kiln I couldn't solve or not knowing what to do. I was also worried because I purchased the kiln used and I was hoping I didn't buy a lemon or something. Well all that's behind me and I can now say I highly recommend facing your fears.

middle shelf after firing

I have a Skutt Model 181 which was new in 1988, so it's 21 years old. It has a 22" x 17" heating area and has a sitter, which means it is manually operated but will turn off automatically by the sitter. The woman I purchased it from previously used it to fire porcelain china dolls and it is in very good condition. It came with shelves and posts and some supplies. I purchased a pyrometer and installed it so I would know the temperature inside the kiln as the firing progresses.

cones on bottom shelf after firing

I made up a set of 30 test tiles for three Cone 5/6 clays I purchased from Aardvark Clay in Los Angeles. The clays are Nara 5, a mid fire porcelain good for throwing which fires very white, SRFG, a stoneware red with grog, and Cassius Basaltic which fires an ebony black. I pressed a texture on the tiles and hand formed them into an L shape. Each test tile has a scribed number on the back. For this firing I put three test tiles of each clay on three shelves in the kiln, bottom, middle and top. I also put a set of four pyrometric cones on each shelf, 07, 06, 05, 04. I put a sitter cone 06 in the sitter. I was planning on firing my bisque to 06. What cone do you fire your bisque to? I have heard that many potters fire their bisque to 04 and I am curious why or which cone is better to fire to? I made my test tiles quite some time ago, so I know they are good and dry.

my pyrometer during firing

I pushed the pyrometer into the kiln to the prescribed distance. As the Skutt manual recommended, I put in three spy hole plugs, but left the top one open. I propped the lid open with a stilt and turned the kiln on to low. Previously I had typed up a firing log which is just a grid with a spot for the date, time, temperature, and notes. I kept the firing log close by to observe the firing and document it on the firing log. I can't emphasize enough about using a firing log. I have a good memory, but the documentation is a wealth of information which can be referred to once the firing is complete, especially for a manual kiln, a new kiln, or for a person new to firing. Another use for a firing log is making comparisons to previous firings. When the kiln starts to take longer to fire, this may mean you need new elements or some other type of kiln repair.

cones on middle shelf after firing

I read that the 200 F and 600 F temperatures are critical points in firing. At 212 F water starts to boil, any water left in the clay may boil and cause the clay to explode or crack, so firing slow up to and during that time is important. The idea is to burn off the moisture in the clay but slowly so it doesn't pop, crack or explode. Certain chemicals in clay including chemical water start to burn out from 530 up to 900 F, so this is another critical point in firing and another time to fire slowly to give the clay time to equalize and stabilize. I am presuming the same will be true for a glaze firing as the clay will absorb moisture from the glaze and there are chemicals in the glaze too.

cones on top shelf after firing

According to my log here is how the firing progressed. I began firing at 12:30 p.m. by turning the kiln to low. It took just one hour for my kiln to reach 250 F on low - way too fast. It took another two hours for the kiln to reach 500 F. At 3:00 p.m. I turned the kiln to medium. By 4:00 p.m. the kiln had reached 650 F, too fast again. The Skutt manual recommended leaving the kiln on medium for one hour and then turning up to high. I turned the kiln on high at 4:00 p.m. At 6:10 p.m. the kiln reached approximately 1790 and the kiln shut off automatically. At 6:30 p.m. the temperature had dropped to 1650 F; at 8:30 p.m. the kiln had dropped to 1000 F; at 10:30 the kiln was 550 F. The next morning the kiln read 150 F at 6:00 am. The top spy hole was left out during the whole firing.

cone in sitter after firing

Cone 07 and 06 melted on the bottom and middle shelf. On the top shelf cone 07's top blew off and I am not sure where it went and none of the cones melted. But to be fair the top shelf was very close to the top and the top spy hole was open with the cones directly in front of the hole, next time I need to put the top shelf cones in the back of the kiln on the top shelf. When I examined the top shelf cones 07 and 06 they are both shiny or glassy, see the next to last paragraph for more information about this observation. Oh, I just noticed the top kiln shelf doesn't have any kiln wash on it. I have a lot to learn.

I would like to slow the kiln down at the beginning. I plan to prop the lid up a little higher and to remove one more spy hole. Or perhaps I can just turn the upper control on low and leave the lower one off. What do you think? I will attempt to leave the kiln on low till I pass the 600 F temperature. What do you think about that? I will repeat this bisque firing with the adjustments noted above. I can use the same test tiles and I can replace the Cone 07 and 06 cones and re-use the Cone 05 and 04 cones. What do you think, maybe I shouldn't reuse the cones? If you have ANY comments, recommendations or corrections to my observations, please don't hesitate to let me know, I gladly welcome your thoughts and advice.

Oh, one more thing, remember at the beginning of this post I said I learn something from every blog I read and comment on. Well a short time ago, I asked Kitty of Kitty's Spanish Studio on her blog, how she could tell a clay was vitrified. She said she could often tell a clay was vitrified by the glassiness of the clay. I wondered about that and put that thought in the back of my mind. When I was looking at the cones that melted during the firing, guess what? The melted cones had a different sheen, they were shiny. I'm finding out ceramics is about testing, observation, and record keeping. Really ceramics is a science and an art.

The dahlia above is from my garden and is seven inches across, unbelievable. And today is my 24th wedding anniversary, unbelievable how quickly time flies. And...some ravens are flying in next, so stay tuned.


  1. Hi Linda:
    Major congrats on firing your kiln! I just fired my first bisque too (its cooling down as we speak). This is the first time I have my own kiln and it is all very exciting but also overwhelming. I used to just punch in numbers to fire a kiln at someone else's studio whereas now I feel I should know everything there is to know and do it all perfectly. But, as I (and my husband) remind myself, testing is what this stage is all about. Regarding firing to cone 06 or cone 04: I fired to cone 04. I plan to use mostly "mastering cone 6 glazes" from John Hesselberth and Ron Roy's book. They recommend bisquing to cone 04 as there are fewer problems later on in the glaze firing (e.g., pinholes and quartz dunting) with higher temp bisque. Your glazes do need to be a bit thicker if you fire to cone 04.
    Good luck with your continuing adventures! :-) Miri

  2. Hi Miri, welcome. I heard that about Cone 04 but I wasn't sure. I will have to purchase John and Roy's book. I've read wonderful things about it, but had done high fire previous to this. I see you have a blog about clay and a tropical paradise, I will be visiting you there very soon to see what you are doing with clay and plants - this is so nice to meet you here. Thanks for visiting and your comments.

  3. Hello Linda,

    Glad you worked through your "first firing" fears!

    You can't reuse the pyrometric cones once they have been exposed to the heat of a kiln.

    When you glaze fire the "molecular" water has already been released (during bisque firing) so if you allow your glazed bisque to dry completely you shouldn't need to slow down at the lower temps as before.

    It's good you are aware of the difference in temp from the bottom to top of the kiln. If there is no hole in the lid of your kiln (mine has a small one) you might want to prop the lid open about 1/2 inch and put all the plugs in except for the bottom one until the temp is around 1000 deg F. This will help equalize temps and allow the gases from firing to escape.

    Venting the kiln is very important during bisque firing as organic matter is burning and a fair amount of water is converted to steam.

  4. Hi Adron, welcome. Thanks, I won't reuse the cones then, I kind of figured that but it didn't hurt to ask about it. My kiln doesn't have a vent in the top, I did keep it propped open one inch at the beginning, this next time I was going to prop it open 2 inches to slow down the rapid accumulation of heat. My kiln manual said if I didn't keep the top spy hole open, the organic matter might try to escape through the sitter and damage the kiln, so I agree with you there, I will leave the top spy hole open through the firing.

    When I was firing for the first 600 degrees or so I did smell things burning and after that I didn't detect any burning smell, so I assumed the organic matter was burnt off. Thanks ever so much for your information and advice, every little bit helps. I will be doing another bisque test firing this week to smooth out some of the discrepancies and rapid heat gains. I have some greenware waiting in the wings, but don't want to risk them till I can bisque them with some confidence.

  5. Hurray for the first firing of your kiln. And congratulations on your anniversary! Tip #39 in the tips section of bigceramicstore.com has a good discussion of choosing a bisque temperature. (We bisque at 05 and candle for 9 hours.)

  6. Hi Barbara, thanks, I will check the big ceramics store discussion, thanks so much. I think bisque at 05 is a happy compromise between 06 and 04. I am not sure about candling that long though. I am going to try for a couple of hours and only put really dry work in there if I can; we shall see. Of course the best laid plans are meant to be broken.

  7. It is great reading all this, I am so glad the firing was successful. From this very careful and measured beginning you can go on and push the boundaries.

    I have been known to make fire and glaze in 3 days. 9years ago I had an order that was so great I couldn’t turn it down; the problem was I had to deliver it within 72 hours. It was for 50 personalised mugs. The brief was fairly free, the design was completely up to me the only condition was they all had to have “The Graduate” written on them and be individually boxed and gift wrapped and delivered to the stage door of the Gielgud Theatre in Shaftesbury Avenue by 5.00pm in 3 days time.
    I worked all morning of day 1 making 80 mugs on a jigger jolly machine, put on handles 4 hours later, in the afternoon I dipped them all into slip and lost about 15 to handles dropping off. Then I force dried them through the night.
    Day 2, bisquit fired them still damp in 6 hours, crash cooled (lost none) and in the evening dipped all into majolica glaze while warm to drive off some of the water. Threw every colour of stain I had at them then devised a cradle and sign wrote them all (lost another 10 at least in this bit, 51 survive). Back into the kiln (still damp) for a 7 hour glaze fire (about 1.00 am by now) unpack on day 3 at 400 Celsius in gauntlets (all survived).
    I had my other half on packaging. They were wrapped and in the boot of the car with a 3 hour dash to London to deliver before the curtain went up.
    My client was Jerry Hall; the price I charged was astronomical, the London west end custom is for the leading lady to have a gift to all the cast and crew before opening night or bad luck will prevail for the run of the show.

    A picture of the 51st mug is on my blog with link back to this Linda.
    So you see, you can break the rules when they really HAVE to be broken!

  8. Goodness, what an exciting account of Kitty's of potting under pressure! Help, the thought of unloading the kiln at 400 Centigrade is quite something!

    Anyway, congratulations Linda and Gary on your 24th wedding anniversary (ours was in 2005!!!). Your 7 inch dahlia is obviously wishing you all good things on behalf of the garden plants!

    Congrats too on your kiln firing and for being methodical with it. You can learn so much that way, and it can be such a problem solver sometimes to be able to look back at a well kept log of a past firing and compare notes. Adron is quite right about the cones, they shouldn't be used again as they will have been affected by the firing, even if they don't yet droop.

    You will almost certainly find the kiln slower with a full load on board. I have occasionally just used the lower elements on my kiln on their lowest setting, and have had the others switched off, when just heating things gently at the start of a firing.

    Good luck, and have fun!

  9. My first electric kiln was a Skutt and it lasted me for years. I used it almost every day for bisque and it performed very well.
    Congrads on the anniversity, that is a grand feat.

  10. Hello Linda and hello USA.
    I like your account about your kiln and Kitty Shepherds about the impossible commision both very interesting.

  11. Hi Kitty, thanks and what an exciting story, can't wait to see the mug, that's really pushing the limits with only 51 to fire in the end - I'll bet you had a bit of fear of not having the 50 in the end, but all is well that ends well. And now you have the one as a rememberance.

    I am sure as I progress along I will be breaking the rules with firing. I very quickly did this working with clay. One thing I would like to try is once firing. Several folks have mentioned this on their blogs and I would love to be able to do try it.

    Hi Peter, yes Kitty's story is truly exciting, I surely wouldn't want that kind of pressure on a job.

    Thanks about our anniversary, Gary said he thought we'd only been married yesterday, which was nice of him and I said, well maybe last week anyway.

    I'll toss the cones and begin again with another test, still with tiles and no work though till I get it right. thanks for your info, it is all helpful.

    Hi Ron, thanks, we have definitely been on some adventures in our marriage and continue so, it keeps us young.

    I have a really good feeling about this Skutt, although I have already been dreaming about one with a controller. But perhaps it was meant to be this way so I learn the ropes of firing before I get to go to 'automatic' mode.

    Hello Richard and welcome, and hello United Kingdom ? - am I correct about the flag on your bag? Thanks so much, sometimes firing is exciting and surely the most exciting is opening up in the end to see the (hopefully) good results of your work. I look foward to firing some of mine very soon.

  12. Wow! New kiln, anniversary, flowers blooming... Life doesn't get much better than that! Bravo on all!

  13. Hi Patricia, thanks, June is definitely turning out be a great month. I am feeling really excited with all the potential of what I can do at home firing my own kiln.

  14. If someone made a comment or sent me an email this afternoon, I believe it was lost in space, please resend, thanks.

  15. i had a bit of trepidation when i fired the maiden firing with my kiln and i just kept reminding myself that as long as it is over a foot from a wall, there is nothing to worry about... the heat is meant to stay in and electricity may be a mystery but it doesn't have a life of its own meaning that the worst would be a short, a tripped breaker or a blown fuse, i hardly give it a second thought now.

  16. And I thought a week was pushing it! No way I could ever push 80 mugs to finish in 3 days...

    Congratulations on your maiden firing - very exciting. My top shelf on my ancient Paragon also fires cooler than the lower - in fact, I did an element check empty recently thinking I had to replace the top element, but all were glowing red on inspection at high. Even though it's firing cooler - I have a work around now if it's my work and not my kid's class work. I place empty top shelves near the lid because I suspect that there is air leaking in through the lid. It acts to insulate the lower shelves - so far so good. I'm pretty sure that my paragon is from the 70's - though the elements were apparently replaced in the 80's.

  17. Linda - Congratulations! A fun way to learn your electric kilns hot/cold spots and how it fires is to use it for a modified raku firing. I have a post on my blog about how I do that - actually learned/adapted the method from another potter who always 'broke in' his kilns that way. He did fast fires, I do 'em slow - you get a good read on temps, don't risk losing a lot of ware, the raku effects are amazing and you get a chance to see exactly how your kiln fires.

    Also, thanks for your constancy and support on my blog. You are wonderful.

  18. Hi Julia, thanks, I will have to check your blog for that modified raku firing. I had heard that using a kiln for raku can shorten the life of the elements, but perhaps your method is different. I do love the look of raku. One of these days I hope to visit you at your farm, hopefully if we ever sell our house. Perhaps the economy is picking up a bit and we'll have some good luck soon.

  19. Linda,

    Congrats on firinf the kiln! I ahve the same apprehension on doing raku i my back yard....afraid to burn down the 'hood. Plus not to mention my neighbor is kinda cranky most of the time...and complains mucho.

    Good luck in future firings, and the first one will be one of very many, salud!

  20. omg....I promise I do know how to write and type. lol....

  21. Hi Yolanda, thanks, too bad about your neighbor, perhaps if you gave him/her a little pinch bowl as a peace offering, they'd warm up? I am really looking forward to being able to fire here at my home instead of relying on someone else. I have lots of plans.

    Oh I knew what you meant, blogs are meant to have small glitches as they are in the here and now.

  22. Hi Jim, thanks I am sure it will become old hat soon.

    Hi Cynthia, thanks, well I am glad to hear about your Paragon working for so long with trouble, that gives me hope about this one. Skutt says to fire with the top spy open, so that's probably why the top was cool. We shall see how it goes; I am excited though.


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