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maryhstudio

cone 6 red glazes

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I've been testing red glazes from recipes I've gotten on the web, and in cone 6 glaze books.  tin, chrome, and copper, depending on the recipe.  I follow each to the letter and fire at cone 6 oxidation in my electric kiln.  They all come out GREEN!!  What am I missing, or doing wrong?  I bisque the test tiles which are made from cone 6 white clay, very porcelain-like.  Any help or advice is appreciated (I am tearing my hair out... well, not literally!).

Thanks!

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Chrome tin reds just need the tiniest bit of chrome, like in the range of 0 point 2 If you are making up a 100 gram test batch you need a well calibrated scale that can accurately do tenths of a gram. Sounds like you just used too much chrome for those tests. Copper reds are fired in reduction to get red, you will get green in an electric kiln.

Welcome to the forums :)

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if you want a really red red, the color of a valentine heart, you can get commercial glazes in bottles to fire at cone 6 in an oxidation firing in an electric kiln.  i would never use that kind on the interior of a piece that will hold food because the color probably comes from cadmium.  you cannot guarantee that your particular piece is safe to use for food because you probably do not have exquisite control over your firing.

as Min, the glaze guru says, the recipes you are following are made for reduction firing, something that cannot be done in a normal electric kiln without ruining it.

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1 hour ago, oldlady said:

the recipes you are following are made for reduction firing, something that cannot be done in a normal electric kiln without ruining it.

Guess I didn't write very clearly in my first post, chrome tin reds work in electric kilns, just have to have a compatible base recipe. Can get purple tones by using the same principle and adding a tiny bit of cobalt to the chrome/ tin red. Copper reds are done in reduction.

Sorry for the confusion.

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5 hours ago, Min said:

Chrome tin reds just need the tiniest bit of chrome, like in the range of 0 point 2 If you are making up a 100 gram test batch you need a well calibrated scale that can accurately do tenths of a gram. Sounds like you just used too much chrome for those tests. Copper reds are fired in reduction to get red, you will get green in an electric kiln.

Welcome to the forums :)

Thanks Min! So I can't get a good red in oxidation?  I've been doing this for a long time, but have purchased a lot of my glazes, and also made some successful ones myself, but red has been a rel challenge.  

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4 hours ago, oldlady said:

if you want a really red red, the color of a valentine heart, you can get commercial glazes in bottles to fire at cone 6 in an oxidation firing in an electric kiln.  i would never use that kind on the interior of a piece that will hold food because the color probably comes from cadmium.  you cannot guarantee that your particular piece is safe to use for food because you probably do not have exquisite control over your firing.

as Min, the glaze guru says, the recipes you are following are made for reduction firing, something that cannot be done in a normal electric kiln without ruining it.

What about making a red glaze with a cone 6 abase glaze and adding a mason stain for the color?

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You can get a pretty good red with chrome/tin. It will always be a little to the raspberry side, though, not a blood red. Also, because of the tin, the glaze will be opaque, so it won't have the depth of color like a copper red.

If you want to get really technical, you could work on a copper red using silicon carbide for localized reduction. Tom Turner did a lot of work with that method, and said he had better results than in the gas kiln. You should be able to find his paper on it with a little Google searching.

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I have recently carried out some successful trials using saggars to produce cone 6 copper red reduction glazes in an electric kiln.  I generated a reduction atmosphere by adding a small amount of  black iron oxide mixed with powdered charcoal to the bottom of a saggar with a test piece painted with Selsor Red (formula see J. Britt -  The Complete Guide to Mid-range Glazes pg 100).  The iron oxide/charcoal mixture produced a reducing carbon monoxide atmosphere within the saggar during firing to cone 6 which turned the glaze oxblood red (see attached photo). The atmospere within the kiln remained oxidizing  as witnessed by the fact that test patchs of the same glaze , on the outside of the saggar, remained green.  I am currently  planning further trials.

Saggar_trial.jpg

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16 hours ago, maryhstudio said:

So I can't get a good red in oxidation?

Yes you can, I think you probably just made an error with measuring out the chrome with your chrome tin red. Base glaze has to have lots of calcium and zero zinc and lowish alumina. 

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18 hours ago, neilestrick said:

You can get a pretty good red with chrome/tin. It will always be a little to the raspberry side, though, not a blood red. Also, because of the tin, the glaze will be opaque, so it won't have the depth of color like a copper red.

If you want to get really technical, you could work on a copper red using silicon carbide for localized reduction. Tom Turner did a lot of work with that method, and said he had better results than in the gas kiln. You should be able to find his paper on it with a little Google searching.

Thanks for the tip!

Edited by maryhstudio

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that is impressive. The liver color comes from not reoxidizing after reduction. You could try using a slightly thinner application for this one. I gave John Britt all the glazes we used at Montana State  University-Billings  from 1980-2000 for ^6 reduction when  I reduced the firing temperature for classes.. This red was a good one. He has tweaked many of them for his book. If you go to my gallery I have the raspberry recipe posted beneath the photo. I believe it is under the album Forum discussions.

 

Marcia Selsor

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3 hours ago, Marcia Selsor said:

that is impressive. The liver color comes from not reoxidizing after reduction. You could try using a slightly thinner application for this one. I gave John Britt all the glazes we used at Montana State  University-Billings  from 1980-2000 for ^6 reduction when  I reduced the firing temperature for classes.. This red was a good one. He has tweaked many of them for his book. If you go to my gallery I have the raspberry recipe posted beneath the photo. I believe it is under the album Forum discussions.

 

Marcia Selsor

Thanks Marcia, but I’m looking for a cone 6 oxidation red !  I shan’t give up...

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here is a red ^6 Oxidation glaze. Th recipe is in my gallery under forum discussions. The tin and chrome  are  in the stain.

Recipe ^6 Oxidation red 

This is using 10% deep crimson Mason stain in a glaze altered by Ron Roy for Sue Hintz 

Version#2 ^6 OXIDATION

Cornwall Stone 33.5

G200 22

Whiting 18

Ger. Borate 10

EPK 5.5

Silica 11

Bentonite 2

 

Mason Stain Deep Crimson 10%

 

gallery_1954_167_316937.jpg

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@oldlady, go to Marcia's homepage on this forum, then go to her gallery tab. On page 3 of Marcia's gallery there is an album called "forum discussions", the recipe is there, first comment under the picture of the red pot.

 

 

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1 hour ago, oldlady said:

did not find that heading on your website.  was i looking in the right place?

it is on THIS website under members gallery. Follow Min's directions.

Marcia

 

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23 hours ago, Marcia Selsor said:

click on the first link and scroll down to comments for the recipe.

.

 

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On 2/28/2018 at 6:35 PM, why_not said:

I have recently carried out some successful trials using saggars to produce cone 6 copper red reduction glazes in an electric kiln.  I generated a reduction atmosphere by adding a small amount of  black iron oxide mixed with powdered charcoal to the bottom of a saggar with a test piece painted with Selsor Red (formula see J. Britt -  The Complete Guide to Mid-range Glazes pg 100).  The iron oxide/charcoal mixture produced a reducing carbon monoxide atmosphere within the saggar during firing to cone 6 which turned the glaze oxblood red (see attached photo). The atmospere within the kiln remained oxidizing  as witnessed by the fact that test patchs of the same glaze , on the outside of the saggar, remained green.  I am currently  planning further trials.

Hi why-not,

 

thanks for sharing this - your post has inspired me to try the same in my electric kiln - and to my amazement it worked :) I must have put in a bit too much charcoal as I had know idea about the amount required. But the results are promising, here's a dark celadon and a copper red tile.

 

 

IMG_20180526_132856_913.jpg

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1 hour ago, Marcia Selsor said:

great experiment! Congrats. I think porcelain is a better background for the red glaze. An iron bearing stoneware will make it more liver color red. Just saying from experience.

Marcia

Thank you, yes, the next step is indeed to try it on different bodies, and on actual pots.

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