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#1 Venicemud

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Posted 06 April 2012 - 09:54 AM

Lately I have read short descriptions of people using soda ash wash on their bisque fired pieces prior to glaze firing and have several questions: Is it only used on bare bisque fired clay or can it be used over a glaze coat, under a glaze coat, or over underglazes? Does it have detrimental effects on your elements (or bricks) in an electric kiln? At what temperature is it used, low fire, mid fire, highfire, or any fire? Would love to hear from anyone who has played with this.

#2 OffCenter

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Posted 08 April 2012 - 08:09 AM

Lately I have read short descriptions of people using soda ash wash on their bisque fired pieces prior to glaze firing and have several questions: Is it only used on bare bisque fired clay or can it be used over a glaze coat, under a glaze coat, or over underglazes? Does it have detrimental effects on your elements (or bricks) in an electric kiln? At what temperature is it used, low fire, mid fire, highfire, or any fire? Would love to hear from anyone who has played with this.


I was hoping someone would reply to this because I would like to learn more about it, too. If you google "soda ash wash" you will pull up several Clayart threads about using soda ash washes. I'm preparing for a show/sale (Fired Works in Macon GA) now but when I have time I will do some soda ash wash tests. If you do any tests let us know the results. At least one person here is interested.

Jim
E pur si muove.

"But it does move," said Galileo under his breath.

#3 bciskepottery

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Posted 08 April 2012 - 09:39 AM

I have used a mixture of about 1 teaspoon soda ash dissolved in about 12 to 16 ounces of hot water -- water needs to be hot enough the dissolve the ash (hot tap or put in microwave; you need a glass container). I have applied only over bare bisque -- usually vases that are textured and where I have applied and then washed off red iron oxide. I applied by brush, two light coats. Remember that soda ash is a flux -- it may make things underneath it run. And, be mindful of your wax line and avoid getting wash on the bottom -- you could end up sticking to the shelf/kiln wash.

The vases were fired in a gas reduction kiln, cone 10. The result was a nice sheen to the bare clay surface. The clay body was a white stoneware. I've also seen the wash applied on a bare porcelain clay body, fired in gas reduction to cone 10. Again, a nice sheen to the surface.

Have not applied the soda wash over a glaze, so I can't help on that part of your question.

With regard to electric kilns, if you are only doing a couple of pieces per firing, I wouldn't imagine there is a detrimental effect on elements and brick. If you are concerned, you could always put the piece in a saggar.

Melting point for soda ash is 851 C/1564 F. So, you could get the effect at low, medium and hire fire.

#4 JBaymore

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Posted 08 April 2012 - 10:25 AM

I use this technique. High fire.... cone 9 to 14 range.

If I am not going to use ALL of the mixture while it is hot, the soda ash solution is mixed to full saturation at room temperature. Mix small amounts of soda ash into room temperature water slowly, stirring well, until the last little added bit of soda ash does not actually disolve but settles as white particles to the bottom. That is then all that will disolve. The reason for not using hot water in some cases is that if you use hot water, as the water cools off... some of the soda ash will precipitate out of solution. If you plan to use it later on...... or use it in spray bottles... it can clog things up a bit.

The "wash" (solution) is caustic. Be very careful, particulary around your EYES!

I use it only on bisqued clay when it is painted on with a brush. It goes directly on the raw clay surfaces. It can slightly emulate wood firing flashing. Best on bodies with a little iron in them. Don't saturate the clay too much.... it is a source of flux on the silica in the body and can cause the body to over-vitrify if too much is present still trapped within the body's walls.

It tends to migrate with the evaporating water... like what happens with American carbon-trap shinos. (mechanics of this stuff is explained in this article http://www.johnbaymore.com/page81.html ) So the soda ash will tend to accumulate on the surface of the clay. The soda crystals on the surface will tend to brush off if handled roughly, and can leave fingerprints and such. So think about the handling as you store and load. You can approach drying techniques like are done for American carbon trap shinos (wax resist, partially covering with plastic, fans, etc.).

I often use it sprayed through a hand-pumped mister. In that case, it gets put on over both raw clay, bisqued clay, and also over layers of some types of glazes. Again it can emulate woodfire flashing and very LIGHT shizenyu (natural ash deposits). Glazes that flash nice in woodfire or look good in a soda or salt firing are good candidates. Usually it is best when sprayed on very unevenly.

The best way to learn about this one (like most things in ceramics) is to experiment.

As far as an electric kiln goes, as has been said..... a few pieces now and again is not really an issue. A whole kiln load of pieces tightly packed in there and also saturated heavily with soda ash solution is likely another story for both the soft brick as well as the elements.

best,

.......................john
John Baymore
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Professor of Ceramics; New Hampshire Insitute of Art

http://www.JohnBaymore.com

#5 OffCenter

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Posted 09 April 2012 - 08:40 AM

I use this technique. High fire.... cone 9 to 14 range.

If I am not going to use ALL of the mixture while it is hot, the soda ash solution is mixed to full saturation at room temperature. Mix small amounts of soda ash into room temperature water slowly, stirring well, until the last little added bit of soda ash does not actually disolve but settles as white particles to the bottom. That is then all that will disolve. The reason for not using hot water in some cases is that if you use hot water, as the water cools off... some of the soda ash will precipitate out of solution. If you plan to use it later on...... or use it in spray bottles... it can clog things up a bit.

The "wash" (solution) is caustic. Be very careful, particulary around your EYES!

I use it only on bisqued clay when it is painted on with a brush. It goes directly on the raw clay surfaces. It can slightly emulate wood firing flashing. Best on bodies with a little iron in them. Don't saturate the clay too much.... it is a source of flux on the silica in the body and can cause the body to over-vitrify if too much is present still trapped within the body's walls.

It tends to migrate with the evaporating water... like what happens with American carbon-trap shinos. (mechanics of this stuff is explained in this article http://www.johnbaymore.com/page81.html ) So the soda ash will tend to accumulate on the surface of the clay. The soda crystals on the surface will tend to brush off if handled roughly, and can leave fingerprints and such. So think about the handling as you store and load. You can approach drying techniques like are done for American carbon trap shinos (wax resist, partially covering with plastic, fans, etc.).

I often use it sprayed through a hand-pumped mister. In that case, it gets put on over both raw clay, bisqued clay, and also over layers of some types of glazes. Again it can emulate woodfire flashing and very LIGHT shizenyu (natural ash deposits). Glazes that flash nice in woodfire or look good in a soda or salt firing are good candidates. Usually it is best when sprayed on very unevenly.

The best way to learn about this one (like most things in ceramics) is to experiment.

As far as an electric kiln goes, as has been said..... a few pieces now and again is not really an issue. A whole kiln load of pieces tightly packed in there and also saturated heavily with soda ash solution is likely another story for both the soft brick as well as the elements.

best,

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


Wow! Nice reply. That just about covers it. I guess you're not such a bad guy after all.

Jim
E pur si muove.

"But it does move," said Galileo under his breath.

#6 Pres

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Posted 09 April 2012 - 10:22 AM

I use this technique. High fire.... cone 9 to 14 range.

If I am not going to use ALL of the mixture while it is hot, the soda ash solution is mixed to full saturation at room temperature. Mix small amounts of soda ash into room temperature water slowly, stirring well, until the last little added bit of soda ash does not actually disolve but settles as white particles to the bottom. That is then all that will disolve. The reason for not using hot water in some cases is that if you use hot water, as the water cools off... some of the soda ash will precipitate out of solution. If you plan to use it later on...... or use it in spray bottles... it can clog things up a bit.

The "wash" (solution) is caustic. Be very careful, particulary around your EYES!

I use it only on bisqued clay when it is painted on with a brush. It goes directly on the raw clay surfaces. It can slightly emulate wood firing flashing. Best on bodies with a little iron in them. Don't saturate the clay too much.... it is a source of flux on the silica in the body and can cause the body to over-vitrify if too much is present still trapped within the body's walls.

It tends to migrate with the evaporating water... like what happens with American carbon-trap shinos. (mechanics of this stuff is explained in this article http://www.johnbaymore.com/page81.html ) So the soda ash will tend to accumulate on the surface of the clay. The soda crystals on the surface will tend to brush off if handled roughly, and can leave fingerprints and such. So think about the handling as you store and load. You can approach drying techniques like are done for American carbon trap shinos (wax resist, partially covering with plastic, fans, etc.).

I often use it sprayed through a hand-pumped mister. In that case, it gets put on over both raw clay, bisqued clay, and also over layers of some types of glazes. Again it can emulate woodfire flashing and very LIGHT shizenyu (natural ash deposits). Glazes that flash nice in woodfire or look good in a soda or salt firing are good candidates. Usually it is best when sprayed on very unevenly.

The best way to learn about this one (like most things in ceramics) is to experiment.

As far as an electric kiln goes, as has been said..... a few pieces now and again is not really an issue. A whole kiln load of pieces tightly packed in there and also saturated heavily with soda ash solution is likely another story for both the soft brick as well as the elements.

best,

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


Because of the wear and tear on the elements I have never tried this technique in an electric kiln, I did do some in the 80's at penn state with mixed results, even tried it with some salt firings. I have also not tried the local reduction reds that were of interest in the 80's and 90's for the same reason.

Simply retired teacher, not dead, living the dream. on and on and. . . . on. . . .                                                                                 http://picworkspottery.blogspot.com/


#7 Marcia Selsor

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Posted 10 April 2012 - 06:03 AM

when I was at a recent wood firing workshop, Mike McCullough mentioned applying the soda wash and putting it in packing peanuts for 2 weeks. He said the outgassing from the styrofoam can make spots on the shine glazes when applied over this. I am drying 2 pieces as we speak. I will be firing another gas load in about 3 weeks. I am firing one tomorrow but without this test.
Marcia

#8 OffCenter

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Posted 10 April 2012 - 07:58 AM

when I was at a recent wood firing workshop, Mike McCullough mentioned applying the soda wash and putting it in packing peanuts for 2 weeks. He said the outgassing from the styrofoam can make spots on the shine glazes when applied over this. I am drying 2 pieces as we speak. I will be firing another gas load in about 3 weeks. I am firing one tomorrow but without this test.
Marcia


Interesting. I hope you post the results here.

Jim
E pur si muove.

"But it does move," said Galileo under his breath.

#9 Marcia Selsor

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Posted 10 April 2012 - 07:58 PM

I will and it will be at ^6 reduction.
Marcia

#10 Marcia Selsor

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Posted 10 April 2012 - 08:00 PM

I will and it will be at ^6 reduction.
Marcia

#11 Marcia Selsor

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Posted 10 April 2012 - 08:01 PM

oops..duplicate

#12 Venicemud

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Posted 18 April 2012 - 07:50 PM

I'd like to share the results of my first little experiment with soda ash wash. I sprayed saturated soda ash solution onto a cylinder which had two birds painted with underglaze onto cone 04 bisque-fired B Mix with grog (no iron), leaving part of the surface unsprayed. The cylinder was fired to cone 6 in my electric kiln (large cone 6 down, cone 7 slightly bent). The result was a pleasant satin clear like sheen on one side, with the underglaze design clearly defined. On the other side of the cylinder I had sprayed too vigorously, wetting the underglaze, so that the colors ran a little. As expected, the unsprayed areas were rough - like bisque fired clay.

One could, of course, avoid the runny underglaze danger by painting the design onto the pot at the bone dry stage and fix by bisque firing. More tests are necessary before I can decide if this approach has any advantage over just spraying with a satin clear glaze in the first place. Any ideas?

Joan Klotz (Venicemud)




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