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JLowes

Refiring dry wood fired pieces in electric advice sought

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At a recent group wood firing in an Anagama, the middle and back (front being nearer the fire) pots were fired cooler as the flow wasn't good past the front. The result was very dry surfaces, less glaze melt, and ash deposits that didn't melt fully. Several of my pots suffered these deficiencies. I won't have access to the Anagama until Spring 2018, so I am assessing whether refiring in an electric kiln to Cone 6 would help my situation. I would like to have these pots for sale in the upcoming holiday season, So...does anyone have experience they can share on how wood fired pots do in an electric refire?

My "worst" offenders have Oribe glaze that is a light pink, instead of the typical green. Several pots have small, but very dry ash deposits. I am thinking a Cone 6 electric refire may melt and oxidize the Oribe, and possibly melt the ash. The pyrometer in the middle never got above 2143 F, and then only for a short period. What do you think? Worth trying, or wait until Spring?

Thanks for your help.

John Lowes

Wynhill Pottery LLC

Buford, Georgia, USA

 

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I suggest a cone 10 reduction firing. You never mentioned your clay body as to temp range. Moist wood fires are cone 10-or way past. I am assuming your clay and glaze is all cone 10.

I have often referred my cone 10 salt bots in a cone 10 reduction fire with spectacular results.I do not think a cone 10 oribe glaze will melt well at cone 6.

Cone 10 reduction should be easy for you to find.

let us know how the cone 6 pots flux if you pursue that temp?

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Are these food ware pots? If yes, I would wait for another cone 10 firing. If they only fired to 2143, and refired at cone 6, the clay will not be vitrified enough for food use. 

If they are not for food use (planters, or dry use only pots) then yes you can refire them to cone 6. The cone 10 glazes or the ash will not melt, but you can overspray the pots with cone 6 glazes. The cone 6 glazes might encourage the others to melt. This needs testing, so you might not have time to fully explore this before the holidays, therefore it might be worth waiting for the next wood firing anyways. 

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Good points all. The clay body is Highwater Clays Craggy Crunch. It is advertised as a cone 7-10 clay.  I will have to evaluate which may be food ware and set them aside for a later firing.  I got just a quick look yesterday as I packed them for the trip home. I know one is designed for use as a utensil holder, so isn't really food containing unless repurposed. You never know what the buyer will do with a pot once it's in their possession. Most of what I make are decorative pieces, and wouldn't be an issue. 

I do have two electric kilns in my studio with cone 10 capability, but I haven't fired beyond cone 7 on either to give them  an easier life.  My access to cone 10 gas or wood is through classes at a community art center, or the semi-annual group wood firings. I may just need to suck it up and wait until Spring. I will try one pot with unmelted ash and try it as cone 6 with a clear to help it flux and see what happens.

Thanks for weighing in.

John

Edited by JLowes

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Guest JBaymore

Very common to refire wood fired pots that need additional heatwork (because of the original firing) to cone 10 or more.  (I have access to my own wood kiln and the college's, so I tend to just re-fire work in the next wood firing.)  I don't think cone 6 will do all that much for them.  Won't have a lot of impact on the body's vitrification level if it is not yet done.   It likely WILL change the way they look (surface changes).  However, don't expect the "crusty" deposits to suddenly fully flux out and get runny and liquid in a cone 6 firing.

If you have an electric kiln that is rated for it.... go to cone 10.  Or to cone 10 in your own or someone else's gas kiln.

I often get changes in surface appearance with the overglaze (015) enamel and luster firings (020) I do . So a refire to almost any temperature can affect the surfaces.  My shino gets really nice impacts from the overglaze firings.

Historically, the big "breakthrough" in Japan in firing work as early sueiki wares "morphed" into work with more natural ash deposit glazing on the forms  was when the true anagama style kiln design (arrived  via Korea out of China) could hit about 1200 C.  That is the "magic number" for the woodash's calcium, potassium and sodium content to begin to really effectively "steal" and flux the silica from the clay body on the surface of the work ( called shizenyu).  At a typical rate of climb for cone 6 you are JUST flirting with this temperature.  So it will have an effect....... but not all that much.  Because it (likely) is already partially in a melt, the glassy content will change more than just wood ash sprinkled on the surface of a new piece at cone 6 would.

Applied glazes on that work......... hard to say exactly what it will do.  Likely will change them appearance wise also.

best,

........................john

 

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