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docweathers

Chrome tin red stability

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I have a number of chrome tin reds. Sometimes they work really nice and sometimes they come out a yuck gray. As far as I can tell , I'm doing everything exactly the same with the same raw materials with the same formulas, same firing schedule etc. but something is obviously different for the different outcomes.  I am firing ^6 oxidation. Any suggestions would be greatly appreciated.

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Chrome-tin reds are finicky, very narrow range for success. If the ratio of chrome to tin is mismeasured, or if the chrome-tin combination is used in a different base, it might not work. Also, they need a thicker application, and will be blah gray if too thin.

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As everyone has said, these are finicky, in my estimation some of the toughest glazes to fire and get consistent results. I have tried them with several thin dipped coats on test tiles,  a  with a single thick coat. Several thin worked best. I have also found that they do not like some other glazes on the shelf, some zinc based glazes seem to mess with them??? cross fuming??? But I do know that kiln position and kiln atmosphere has something to do with them. 

We had a popular tin based pink for years, and it was what I called a forgiving glaze when it did not work as it was usually a decent white . When applied properly it would be a beautiful rich pink. I found that it would settle super fast, almost as fast as stopping the drill mixer. So tried some epsom salts in it as it caked a bit, and some ball clay, that did not change the glaze, but it became more consistent. IT was a commercial glaze. 

I think the only answer here is to keep fiddling with it until you get it to work.

 

best,

Pres

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25 minutes ago, Pres said:

As everyone has said, these are finicky, in my estimation some of the toughest glazes to fire and get consistent results. I have tried them with several thin dipped coats on test tiles,  a  with a single thick coat. Several thin worked best. I have also found that they do not like some other glazes on the shelf, some zinc based glazes seem to mess with them??? cross fuming??? But I do know that kiln position and kiln atmosphere has something to do with them. 

We had a popular tin based pink for years, and it was what I called a forgiving glaze when it did not work as it was usually a decent white . When applied properly it would be a beautiful rich pink. I found that it would settle super fast, almost as fast as stopping the drill mixer. So tried some epsom salts in it as it caked a bit, and some ball clay, that did not change the glaze, but it became more consistent. IT was a commercial glaze. 

I think the only answer here is to keep fiddling with it until you get it to work.

 

best,

Pres

Yeah, I believe zinc turns any chrome/tin brown.

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The one I use has never had any problems with settling, other glazes near it, shelf placement, etc. The only issue is thickness. If I remember correctly, it's the one from the Mastering Cone 6 Glazes book, but I tweaked it because it was too stiff. So maybe look at that, too- maybe a little more melt will help develop color.

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Low alumina usually sodium calcium based. You might try another, I have  attached a staple on glazy that you might want to give a whirl. Generally very low concentrations of chrome .2% for a bright red

9B12A2A3-E095-4BC7-A481-19BFCE8B3391.jpeg

A4E9AFA9-3009-481D-ADAE-22B8E5598ADE.jpeg

Edited by Bill Kielb

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On 2/17/2019 at 9:30 PM, neilestrick said:

The one I use has never had any problems with settling, other glazes near it, shelf placement, etc. The only issue is thickness. If I remember correctly, it's the one from the Mastering Cone 6 Glazes book, but I tweaked it because it was too stiff. So maybe look at that, too- maybe a little more melt will help develop color.

I gobbed it on thick  on 5 chrome tin  recipes and they all  cam out nice reds... Thanks 

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On 2/17/2019 at 9:30 PM, neilestrick said:

The one I use has never had any problems with settling, other glazes near it, shelf placement, etc. The only issue is thickness. If I remember correctly, it's the one from the Mastering Cone 6 Glazes book, but I tweaked it because it was too stiff. So maybe look at that, too- maybe a little more melt will help develop color.

I gobbed it on thick  on 5 chrome tin  recipes and they all  cam out nice reds... Thanks 

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Tin levels are say 2- 10% with very low chrome concentrations. Range from pink to cranberry to red In a low alumina sodium calcium glaze. I would pick your favorite and do a color progression starting with varying the tin and a low chrome base amount until you find your desired shade.

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The local JC red recipe is exact same (chrome oxide at 2%). My classmates said the red goes away when covered by the clear ...have a few examples... th' whitish around the knob is red that turned, and the blotches at the rim are likely retouches; the techs will touch up the glazes when some is bumped off in loading, but they can' alway pick the right one, eh?

The rectangles in the blue are same JC red, looks like the colour survived where that glaze is thickest. There the blue was sprayed on; the rectangles are where I'd placed tape for scratch off thickness testing...

Thanks for posting that recipe Bill! I like that red (seems to 'have fairly well), have alla 'gredients 'cept tin - next order...

Oh, the clear on these is JC "Functional Clear" (which I'm not using at home); the blue is Lakeside Pottery Clear Blue (recipes in same order).

 

 

with red.JPG

fc.JPG

lpcb.JPG

Edited by Hulk
oops

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@Hulk

@docweathers

Oops!

Blend out the whiting!

Just got this sent to me. Nice minimal tin recipe, you might want to blend around a bit. David says his progression is a blend from whiting to dollmite. Durable recipe to start as well, who would have figured?

Sorry best I could do with the picture

 

 

ED16484A-5EB2-40B2-B109-8281EF06CC11.jpeg

Edited by Bill Kielb

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2 hours ago, Bill Kielb said:

Blend out the whiting!

Just got this sent to me. Nice minimal tin recipe, you might want to blend around a bit. David says his progression is a blend from whiting to dollmite. Durable recipe to start as well, who would have figured?

thanks  looks good

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On 2/21/2019 at 6:48 AM, Hulk said:

(chrome oxide at 2%)

Think you forgot a decimal, .2% would be the chrome.  2% would get you one very green (and probably very unattractive) glaze. 

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If I may make a suggestion to all folks posting a glaze recipe which contains percentages less than 1%, please put a zero before the decimal point .

3 hours ago, Hulk said:

you right Min, .2%

It is easier to understand the above if it reads: “you right Min, 0.2%”

Regards,

Fred

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