Sunday, August 29, 2010

Cone 5/6 Firing Schedules ?


More apprehension is lurking. Why? I realize I have four different clay bodies and glossy and matt glazes for the work I plan to fire tonight. What firing schedule should I use for this glaze fire?

The pieces in the two photos were fired Cone 5 with a 10 minute hold. I don't have those exact schedule right now since another potter fired them for me.


I'll split up the load into at least two, so I won't risk it all in one load. I want a slow cool down so the matt glazes will have a chance to develop. After reading and searching, I've come up with a couple of scenarios.

Schedule One

Seg-Rate-Temp-Hold
1 - 100 - 200 - 0
2 - 350 - 2000 - 0
3 - 150 - 2156 - 15
plug top peep
4 - 500 - 1900 - 0
5 - 125 - 1400 - 0
6 - freefall - 86 - open kiln

Schedule Two

Seg-Rate-Temp-Hold
1 - 60 - 212 - 60
2 - 200 - 1976 - 0
3 - 85 - 2156 - 15
plug top peep
4 - 275 - 1832 - 0
5 - 70 - 1400 - 0
6 - freefall - 86 - open kiln

What do you think? I'm leaning towards the second one, which is an adaption from Digital Fire. The first is my adaption from John and Ron's Mastering Cone 6 Glazes.

Any and all advice and reasons for your rationale are welcome. I'm aiming for cone 5.5 since a couple of the glazes are rated for Cone 5 and I don't want to over fire those. All the clays are rated for 5/6 and a few non functional pieces at Cone 8/10. Comments and suggestions are welcome.

21 comments:

  1. Oh, I'm sorry I can't help you.. I have no clue..
    I just wanted to say that I adore that green glaze in the second picture!!
    Is that the one wit the RIO wash under it?
    I have not been able to make a gaze like that. Love it!

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  2. Hi Linda! I have been lying low, but I enjoyed all your recent posts. Love hearing you talk of what makes you happy. Teresa

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  3. I'm a lazy firerer... a potter not much interested in the firing part, so I go on auto-pilot with my electric kiln... I know, I know, kind of a pansy potter. If I've got large pieces in the bisque, I go for a slow cone 05, over 13 hours. It's followed by a fast glaze firing (cover 5) with a 10-minute hold.

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  4. Hi Monique, thanks, yes that is another bowl with the RIO. The RIO is fired on in the bisque, then the light turquoisey green glaze brushed on over the top and fired again for the glaze load. A diluted solution of the RIO is best and unevenly put on the bowl. The bowl had a medium heavy texture, so the glaze pooled in the crevices and made the different colors. Just try any one of your regular glazes over rio or any other wash which has been bisqued with it. I put the Rio on when it's bone dry and try not to put too much moisture in any one spot, then I let the piece dry out a few more days before I bisque it so the moisture escapes.

    If you look back at my original post on that bowl, you will see there were white spots showing that were not covered with the RIO. Also this was frost porcelain clay, porcelain clay gives beautiful glaze results, but for my hand built work more risk of cracking.

    Once I get all my work made I'm going to make lots of test tiles with texture, some covered with porcelain slip on stoneware to see what I can come up with.
    Hi Teresa, thanks, glad you are enjoying my posts. Take er easy.

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  5. Hi Patricia, thanks, I think that's what my potter friend uses for her glaze fire, fast and 10 minute hold, she bisques at 04 slow. I may go to that but want to try slow these first couple of times. Thanks so much.

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  6. Hi Linda..(I posted back on my blog about the warping thing)..

    The firing schedule..I commend you on figuring that all out. I try to fire according to 'mastering' book too, but my kiln is not computerized, so I do the manual turning up and down etc., and I do not pay strick attention to the degrees per hour thing at all times. I watch my guard cones on a couple of levels,and the pyrometer mostly at the peak, soak for 15 - 20 minutes, crash cool to 1800, then turn kiln back on to slow cool to 1400 (trying to get minus 60 degrees in each hour), then put the bottom on low for 3 hours, then off completely. I fire to cone 6/7. The bottom and top of my kiln is cooler so I put the pieces which are better at 6 or less on the bottom or very, very top.

    I really like both glazes in the pictures, and will try the RIO idea. good luck

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  7. Hi Trish, thanks, my last kiln, (actually I still have it) was manual too and I did similar to you. didn't know about slow cooling back then though. so far my kiln is firing the same at the top as the bottom, but it is new and elements are new, so over time it may change. I'll check your blog, thanks.

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  8. Hi Linda, It took me almost a year to come up with a good firing schedule for my kiln. I think every kiln fires a little different, even if they are programable.

    I pick your program #2 for the 85 to peak.

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  9. Thanks for the details on that Rio-glaze!

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  10. Clueless here also but from a nonpotter view point, I really liked the second one.

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  11. Hi Linda,
    Best of luck with your firing! How exciting.

    I fire using the MC6 schedule. With experimentation, I've figured out exactly where my cone 6 starts going so I can soak for 15 minutes at that point (I set my program with a long soak so that if things don't quite go to schedule, I can soak for a bit longer until the cones are exactly where I want and when they are, I skip to the next segment). This is pretty much exactly your first schedule. I also found that I can stop the controlled cool at 1500 with no change in glazes (John Hesselberth told me that is no surprise to him, as the 1400 is really only crucial for highly fluid glazes such as waterfall brown). Next firing or so, I'll likely experiment with only going down to 1600. Mary Starosta says she has had great success with doing just that, and no changes in her matte glazes.

    Just wondering, Is there a reason you keep the top plug out? Do you have a vent?

    Miri

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  12. Hi Jen, thanks for stopping by.

    Hi Cindy, thanks for the info.

    Hi Monique, hope it works for you.

    Hi Patti, thanks, another vote.

    Hi Miri, thanks, I modified the second one a bit again as it was too long I think and too conservative. I don't have a vent so the top peep stay out. I now wish I had gotten one, but our garage is block and we'd have to cut through the block to vent it outside, unless we could lay a pipe along the garage floor for quite a distance, what do you think. I think with a vent it improves firing due to better air ciculation.

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  13. hi linda, i think i use the john and ron's one right out of the book... hasn't failed me yet but i don't have any cone 5 firing either. pretty sure it only goes down to 1500, can't imagine that last 100 makes much difference but just when you think you know better, it bites you in the butt.

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  14. Hi Jim, thanks, I got on their website and they had modified the program slightly under the FAQ section and it was 1400 but maybe not, I may be confusing the two programs. Anyway I just input a modified second one and I'm firing it now. We shall see. thanks again.

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  15. When I fired to ^6 - I also used the MC6G firing schedule - but I modified it over time to work on my kiln.
    I think it depends on what you're after - the iron red glazes can take a really long soak & also like a long slow cool -- but for just mattes - you'll need to find the 'sweet spot' on your kiln.

    Sorry you can't vent your kiln. I didn't have one for a long time & found after getting one my glazes improved.

    Can't wait to see photos of this firing -- hope it's a good one!

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  16. Hi Judy, thanks, I just talked to Skutt and they said the same thing that the glazes would be better with the vent, I think I will get one, they said I can just run the tube out the garage door instead of drilling through the door. Might as well do all I can to get good glazes.

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  17. Ohhh, Linda, but this is Greek to me. Sorry! Not fair that I can't sweat out the preambles with you, just enjoy the finished product...and, wow, that green glaze is fantastic. Also, it's been end of summer hectic here, missed a couple of your posts. Whenever I do this, I can't seem to find them later (as I like to keep up with what you're doing.) Help!

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  18. Hi Kittie, thanks, look on the right side of my blog and scroll down a bit and you will see the archives and the title of each post and you can click on those or you can click on older posts after the place where you see where to add your comments. Sorry about the technical stuff, but coming up next are a few pots, just loading them up now.

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  19. Hi, I am a brand new potter with a brand new kiln about to do my first (cone 6) glaze firing at home (only half a kiln load, mostly kids' stuff and test tiles - all using commercial Mayco glazes), so this blog post is very helpful to me!! I hope I can find the "jon & ron" website you refer to, and what "MC6G" is!

    Rebecca
    Madison, WI

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  20. Hi Becca, thanks, and welcome to pottery, isn't it fun. If you click on the link (in yellow highlights in the body of the text) in my post it will take you to the website for John and Robs website which has the book listed for purchase. I highly recommend their book about glaze firing for Cone 6 glazes. The MC6G is an abbreviation for Mastering Cone 6 Glazes, which is the name of their book. Good luck. I hope you start a blog and post some of your work, don't be shy, most people are very willing to answer questions and give you advice. Thanks again and good luck with your firing.

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I love suggestions, questions, critiques, thanks for your comment