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I'm hoping due to time shortage to use soda wash on an unfired piece, has anyone done this. I usually apply soda wash to bisqued ware.

Quick replies appreciated.

Firing once fired to C 03

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PRODUCTION OF A SALT GLAZE BY THE APPLICATION OF A SLIP TO THE WARE
Author  J. Otis Everhart
First published: June 1930
DOI: 10.1111/j.1151-2916.1930.tb16291.x  V

Presented at the Annual Meeting, American Ceramic Society, Toronto, Ont., February, 1930 (Heavy Clay Products Division).

 

ABSTRACT

Glazed surfaces can be produced on the face of ware mode from practically any clay or shale having maturing temperature of cone 1 or more by coating the face of the ware with a slip containing sodium chloride. Various concentrations of salt in the slip have been used. Lower concentrations do not produce glazes but develop interesting surface and color effects. Metallic oxides may be used to produce variation in color of the glaze. This method shows promise as a means of securing salt glazes in kilns which have heretofore been considered impractical for salt-glazing purposes, although it has been developed only in the laboratory stage at the present time. Sodium carbonate has also been used successfully.

http://onlinelibrary.wiley.com/doi/10.1111/j.1151-2916.1930.tb16291.x/full

 

It has been a long while since I read the whole article.  What I remember is summarized below.

The process was based on a slip made with the clay body to which salt was added.  Soda ash instead of salt also works.  The slip was added to the ware after the ware was formed, trimmed, etc.  Think of the slip as glazing the ware for single firing. 

If you are firing in an electric kiln, the soda ash will be the better formulation.  The chlorine from the salt exits the kiln as HCl vapor. 

 

The article may be available through a wide internet search.  I haven't looked for it in 10+ years.  If you are a member of ACERS, you can get it from their website. 

 

If you can not get access to the journal article, send me a pm and I will look to see if I still have a copy.

 

LT

Joseph F likes this

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Now you have me doubting my memories... did I apply it raw??

I usually have used as as bciske, and when making tea vessels, use the soda wash on the bottom third of the vessel, glaze above this.

Decided to go just the clay in this case as pots are bone dry, and I want to pack and fire today.

Never tried it with te additives Marcia, but will when I get a few more pots under my belt.

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 Have try on green ware and bisque, on green it exploded with a loud bang!. Never try it again. It was bone dry when apply and fire to cone 05, it didn't got that far.

On bisque at cone 6 porcelain reduction came out a horrible gray, just the kind you don´t want in porcelain.

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PRODUCTION OF A SALT GLAZE BY THE APPLICATION OF A SLIP TO THE WARE

Author  J. Otis Everhart

First published: June 1930

DOI: 10.1111/j.1151-2916.1930.tb16291.x  V

Presented at the Annual Meeting, American Ceramic Society, Toronto, Ont., February, 1930 (Heavy Clay Products Division).

 

ABSTRACT

Glazed surfaces can be produced on the face of ware mode from practically any clay or shale having maturing temperature of cone 1 or more by coating the face of the ware with a slip containing sodium chloride. Various concentrations of salt in the slip have been used. Lower concentrations do not produce glazes but develop interesting surface and color effects. Metallic oxides may be used to produce variation in color of the glaze. This method shows promise as a means of securing salt glazes in kilns which have heretofore been considered impractical for salt-glazing purposes, although it has been developed only in the laboratory stage at the present time. Sodium carbonate has also been used successfully.

http://onlinelibrary.wiley.com/doi/10.1111/j.1151-2916.1930.tb16291.x/full

 

It has been a long while since I read the whole article.  What I remember is summarized below.

The process was based on a slip made with the clay body to which salt was added.  Soda ash instead of salt also works.  The slip was added to the ware after the ware was formed, trimmed, etc.  Think of the slip as glazing the ware for single firing. 

If you are firing in an electric kiln, the soda ash will be the better formulation.  The chlorine from the salt exits the kiln as HCl vapor. 

 

The article may be available through a wide internet search.  I haven't looked for it in 10+ years.  If you are a member of ACERS, you can get it from their website. 

 

If you can not get access to the journal article, send me a pm and I will look to see if I still have a copy.

 

LT

 

Was this in electric kilns? 

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People use it to give a little color to clay in an electric kiln.  

It looks ok on porcelain with the additives I mentioned above, I have some porcelain I am using ^6 Bray that is too yellow for my tastes. 

I would try this on it next time I do a glaze. 

But I am gearing up for foil saggar firings over the next few weeks.

Marcia

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Joseph,

 

I don't remember that detail; given that the article was published in 1930, I doubt it.  Most likely it was natural gas or fuel oil fired. 

 

My comment about electric kiln with sodium chloride (aka salt) was alert a user that the off-gas from chlorides is HCL vapor (expect in very unusual situations) which is corrosive to hot metal heating elements.  Soda ash produces CO2 as off-gas and is not a significant corrodent to electric kiln heating elements. 

 

When using soda ash, one must understand that soda ash forms various hydrates some of which may not loose its water until above normal water boiling temperatures.  Also the temperature for CO2 off gassing begins around 400 C.  This means that the clay body (including the applied slip) should retain an open pore configuration until all the gas has been liberated. 

 

I don't remember the clay body used in the journal article; my guess is that it was not likely to have been porcelain.

 

 

LT

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