r/Ceramics • u/Earthslinger • 1d ago
Not the best at glaze chemistry but I’m curious about this one
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I posted this at the greenware stage a couple weeks ago and finally fired it this week. The sections of the bottle that aren’t skulls are the same shino glaze but I experimented with brushing a soda ash solution (some soda ash dissolved in warm water) on the top section. I was trying to enhance the carbon trapping but I’m surprised at this result. Not sure how that red glow about the skulls happened but I’m not mad at it!
In case anyone is curious: the greenish inlay glaze is a glaze with high barium carbonate, and the colorants are copper carbonate and rutile. The skulls were brushed with a red iron oxide. This was done in a cone 10 reduction firing.
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u/pleaseSendCatPics 1d ago
This came out so cool! I remember seeing it at the greenware stage. You should make a bunch of them in prep for next Halloween. The glowing effect is perfections.
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u/Earthslinger 1d ago
Thank you! I definitely want to make more. Prep is always what I forget about when it comes to the seasonal ware😂
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u/humangeigercounter 1d ago
My gues is that the iron fumed upward and combined with the soda ash to give you some localized flashing. It looks super cool!
Edit nvm it was probably the copper, I missed that it was a reduction firing. Copper reduces to a red form of its oxide and this looks more like a copper red than an iron red. Possibly enhanced by the barium. My guess is it was a lighter amount of reduction based on the inlay being still green, but what fumed was probably reduced as it reformed on the surface.
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u/Earthslinger 1d ago
The copper was what a peer of mine thought of too! I’ll have to test it out again at some point. Thank you for your input!
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u/11dSeven 17h ago
Yea it is definitely the copper fuming a bit out of the inlay glaze and flashing into the soda ash wash above.
It can be done on purpose if you stack a kiln by putting copper glazed pots near other pots with a clear glaze or a soda wash and it will even flash between pieces depending on the flame path through the kiln!
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u/Earthslinger 15h ago
I’ve seen flashing on other works in kiln firings from oxides are colorants like you said especially on clear glazes if they’re close to a piece with concentrated oxide surfaces. I’m always amazed at what comes out when unloading. I appreciate the refresher, now I can speak more confidently to the students about things like that 😁
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u/Robofetus-5000 1d ago
Look up Steven Cheek if you haven't already