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What should I know about firing schedule?


planetluvver

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Hi, my first post here!

I wish to understand glaze behavior from a more scientific point of view. My instructor's approach of "try it and see" strikes me as wasteful, given that I have a BA with majors in both science and mathematics.

Is there anything else I want to know about glaze firing beyond  temperature and the atmosphere?  (Cone 10 with options of both reduction and "normal" atmosphere. (They use the term normal, rather than oxidation here. I am unsure if there is a difference.)

My instructor was very vague when I asked him about schedules. When I asked about cooling, he only said that the kiln can't be cooled too quickly, lest the contents shatter. 

I own Robin Hopper's book,  The Ceramic Spectrum." However, I am having a lot of trouble applying it to my particular studio environment.

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Glaze firing is extremely complicated.  Do you have a more specific question? Or a specific goal in mind when it comes to glazing?  Cooling schedules can be manipulated to encourage crystal growth (which can cause some glazes to become matte, or some to exhibit actual crystal growth), there's a lot you can do in the glaze stage, a lot of chemical interactions, etc.  You could go crazy if you aren't careful, just ask @glazenerd

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@liambesaw

is correct and your teacher is sort of correct in his own way. Much of glaze chemistry  in ceramics is taught by trial and error with descriptions such as you need a feldspar and some flux and some clay and given enough trial and error you will learn your way around and that is definitely true. If you are more predisposed to a chemical engineering approach then maybe stull and UMF will be a little more concrete but not full on glazenerdery.

Then again there are those that know that reduction is chemistry and means you are gaining electrons and hate when potters say our flame is sucking the oxygen from our glazes!

Glazes can be as complicated as anything and we have not even started to discuss the firing cycle, slow cool, crystal growth, quantifiable durability etc....

Experience  probably carries the most weight as all things even in theory must be verified by testing. My thought: visit Ceramic Material Workshop and see if you like that approach. There are always Digital fire by Tony Hansen, John Britt, Linda Arbuckle and frankly too many to name that have books and a life of experience to share.

I would say explore as many options as keep your interest. Pottery needs good glaze guys and gals and they are hard to find. At our studio we have begun to put together some of the very basics about glazes for newbies. Likely extremely simple for your background but if you like give it a watch. There are a couple glaze videos and even a reduction video.  All pure basics though, maybe too basic or you might get an inkling of what you prefer.

 

 

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Thanks for the info. My chemistry knowledge is pretty old, And my science background is actually more wide than deep. So I would not assume the basics are too basic for me! 

Actually, I cannot manipulate the firing since I am in a school studio. I was just not sure if I should really know more how the firing is done.

I have worked in 4 different studios at various points.  I want more of that knowledge to be transportable if I go work elsewhere.

Yes, my instructor is correct, some effects of the kiln are unpredictable. (As I read, potters choose reactive glaze recipes specifically for that reason.) 

I also have a bit of a confession. I am not a very skilled potter. Perhaps I can find more satisfaction in glaze development. I assume manual dexterity is not critical.

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The best way to understand glaze behaviour is to try it and see. Start melting rocks. 

Altering the firing schedule was always the biggest pain in the butt for me as it took 24 hours~ and a kiln full of stuff to see if anything changed. 

This is a good read for stuff that happens when you fire https://docs.google.com/document/d/1ZldESiqt7z1gIpV-AS80_nA_MRtHKc3MC1SKBew_Y1o/edit?usp=sharing

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There's only so much you can tell about how a glaze will look and behave by looking at the recipe, especially when it comes to color response and surface quality. Firing is the best way to know. Different firing schedules will also affect the outcome, sometimes dramatically. Start with your typical schedule, and make changes from there, wither increasing final temperature, or adding hold times, or experimenting with cooling cycles. If you can't make changes to the firing schedule, then there are a lot of things you can do to the glaze itself. Any decent glaze formulation book will teach you the basics of glaze components to get you started.

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