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Rooster McBlurter

Sagar question glazed pots?

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Hi everyone, my first post!  Getting back into ceramics after a 35 year hiatus and just so much info around these days!!  Have built my own ceramic fiber raku kiln and exploring some ideas.  Really like earthy style, crazing, pinholing etc.  Just found out about sagar and really interested in exploring it more.  A thought I had was to use stoneware, bisque fire, then use earthenware glaze on it.  Would glaze inside, leave outside no glaze.   As stoneware and not vitrified would it still take up sagar method?  Can you (or is it worth doing) sagar on glazed pots, will it stick to or effect glaze in some way. Looking at alfoil sagar, will alfoil stick to glaze at sagar temp?  Sorry if suestion is unclear or not using proper terms, just my mind is overwhelmed with possibilities!!

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A saggar is essentially a chamber inside of another heated chamber (a kiln). The inner chamber can be made from all kinds of refractories, from old kiln shelves, fire brick, clay, etc, or other materials like you are suggesting. Aluminum foil melts at around 1200* F, so keep that in mind if you are trying to reach cone 08-04 temps (1850'ish).The saggar is filled with the pots you want to fire, and then your added combustibles, colorants, etc (seaweed, straw, pine needles, oxides.......) Its essentially like a trash can raku firing, but done inside of the kiln. The nuances in between doing it in a trash can, or doing it in a saggar come with experience; some may claim there is no difference in results, some may find a huge amount of difference.

  The one thing to note here is what you are "fuming" and what it can do to your kiln; having a fiber raku kiln, that you may/may not be willing to damage, takes some of the risk out of the process, compared to if you were going to do this saggar in your electric kiln. Salts and other vapors can penetrate the kiln's insulating materials and eventually lead to their demise; a fiber kiln can be easily repaired, and since you know how to do so, is a huge help up, but fiber (like a sponge) will absorb a lot of vapor. If you get into using a LOT of salts, you may want to look into making a small hard brick kiln, or a very tight fitting saggar, so all the fumes are contained as best as possible.

In regards to your question about glazes/surfaces. Most of the "alternative" firing processes and techniques, generally speaking, produce NON utilitarian wares. Considering you are not making functional ware, then you are only limited by your imagination, and the technical limitations of the materials. For example, an "earthenware" glaze, may not fit well to a stoneware clay body, and may shiver/crawl terribly, or completely off. If thats the look you are going for, then great, if not.....

Aluminum would melt at lowfire temps, which if it hadnt melted away from your pots, would stick to the glaze, if the glaze began to melt. If the glaze hadnt melted, the foil may have, and it may stick to your pots. Aluminum foil is made from an alloy of metals, and those other metals may melt at lower temperatures, and behave differently. I have no experience with this personally, other than salt/soda firing, where aluminum "burritos" of salt are thrown into the fireboxes at cone 6 or hotter. At those temps the aluminum does melt, but the fireboxes of every salt kiln Ive ever fired are so chewed up with soda/ash/pots/etc that deciphering what is the melted AL from other items is difficult.

There are plenty of books out there which discuss alternative firing methods, and some specifically saggar. Books will advise you to use caution, especially with some more dangerous materials, that can fume (some feverishly)and those can be bad for your body. While there are plenty of tried and true materials you can add to your saggar, often folks like finding their own "blends" of items, which dictates their aesthetic choices. In some senses, the world is your oyster. If you want to glaze fire a pot to cone 12, with a combination of slips, glazes, sigillatas, stains, and then re fire in a saggar with salts, pine needles, oxide saturated grasses.......................nothing is gonna stop you other than the limitations of the materials. Will the colors absorb into the pot? Will the pot withstand the heating/cooling? Will the glazes crater and collect burned organic materials.....

Best of luck, and post some of your results! Again, keep in mind safety! Heat, Fumes, exposure to chemicals...........Lots can be dangerous if handled improperly. Generally speaking you'r gonna want a respirator, heavy duty heat resistant gloves, and lots of good ventilation. A face mask, and heat resistant clothing if you're gonna be opening kilns and working on hot pots...

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Thanks Hitchmss for your comprehensive answer!  I think this is what I love about clay, people use what they have at hand and make something out of it, beautiful or functional, or both!!  Maybe I am in a little bit of uncharted waters,so best way to find out is to try.  Yes very keen on being safe, I like the idea of seaweed (I can use the bits I don’t eat!!) and other natural materials, maybe some salts.  Like the idea of ferrous chloride and note the potential harmful effects of this substance.  Crawling, pinholing etc are all good, happy to be on the edge of it working/not working.  Below is an image of a chawan that to me is beautiful, I doubt I can replicate, but will try a few things and see!

Will take me some time to get my head around all the clays/glazes etc, but it is a journey not looking for a destination!

6E895816-514F-4CC6-84D5-79BF9FCCCD85.jpeg

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You probably won't replicate the look of that chawan in a saggar firing. That piece is sporting some really nice toasty ash glaze, with feldspar chunks bleeding through from the clay body. That's out of a wood firing, which is a much different process done at a much higher temperature than saggar firing. Wood kilns can be used to create functional wares, but typically saggar firing is reserved for more decorative or artistic pieces because it doesn't get hot enough to mature the clay properly. Also, if you glaze the pieces first, they tend to be not porous enough to absorb all the lovely carbon effects.

One of our longtime members here, @Marcia Selsor is one of the best artists in North America working in saggar and other alternative firing methods. She just posted some stunning results of her latest firing in the gallery this week. Have a look at them, and hopefully she chimes in here :) 

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Saggar firings can be done at any temperature, and give many types of results. Chinese porcelain was fired in saggars to prevent the ash and vapor of the wood burning kilns from getting to the glazes. Modern saggar firing typically refers to using the opposite- using the saggar to seal a pot within a fuel-rich environment. I've done it at both low fire and high fire temps. At high fire you can go hot enough to melt ash and get wood fired-ish effects. At low temp you get carbon trapping and color flashing, depending on what you use for fuel. I've also seen some beautiful pieces done at mid range temps. You can totally bury pieces, partially bury them, seal them tight or loose, etc. Lots of possibilities, very few rules.

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