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Tumbleweed Pottery

Extremely dark cone 6 clay bodies?

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I'm looking for some clay bodies that are DARK. I have an idea in mind, and I'd like to have a clay as dark as something like cassius basaltic clay. But I've seen that it's SO finicky, and a lot of people have their glazes crater on that clay.

I would like to achieve this kind of contrast between my clay and glaze:

468913574_ScreenShot2019-05-30at7_32_38PM.png.3c4a882f00e1180da87b2990f841243d.png

Sorry for the blur.

Does anyone know of a reliable, tested clay body that is dark chocolate or near black, and fires to cone 6?

*I know these clays can sometimes contain high levels of manganese. Does this render the piece non-food safe?

 

Edited by Tumbleweed Pottery

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Dark bodies have lots of iron disulphide in them, or lots of black stain in them, each have their issues.  My clay bodies fire a dark maroon, which is good, but also have issues with glazes that don't heal well as carbon and sulphur burn out.

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13 minutes ago, liambesaw said:

Dark bodies have lots of iron disulphide in them, or lots of black stain in them, each have their issues.  My clay bodies fire a dark maroon, which is good, but also have issues with glazes that don't heal well as carbon and sulphur burn out.

Sounds like the best way to figure things out is to buy a 25lb bag, and fire a few test tiles with my intended glaze? Then if that works well, move to a small vessel?

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Standard 266 looks like that, but it has bloating issues if you overfire it just a little. Better to fire it to cone 5. It can also react with glazes in unexpected ways, so testing is required with all new glazing schemes. 

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27 minutes ago, Tumbleweed Pottery said:

Sounds like the best way to figure things out is to buy a 25lb bag, and fire a few test tiles with my intended glaze? Then if that works well, move to a small vessel?

Absolutely!  And definitely slow bisque it.  I love the look of iron clay bodies though, so I try to adjust my glaze recipes to have a less viscous melt in hopes the holes will heal over.  Either that or just let the glaze have defects.

I'm gonna be trying out some porcelains tonight and see if I can throw/handle/like them as much as I do the dark bodies, we will see

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https://www.sio-2.com/us/language_changed/subfamily/93

This clay will do exactly what you want but is very expensive and problematic to throw well. *shrugs*

Maybe other's don't have a problem throwing it, but I for the life of me cannot get a pot higher than 12 inches with it, and I can throw all of the "difficult" porcelains just fine.

I have never had black ice bloat, and I have fired it all the way to cone 7, and I also have single fired it with no bisque. The clay is remarkable, and I don't know how they get the dark body, but it doesn't change the color of the glazes on top at all.

Here is a cup with the clay as a slip, which is how I use the clay as I prefer to use it as a slip on my work because of the texture I get using it. (plus its cheaper to use as a slip since I don't have to use nearly as much clay to get the look I am after.

The black area is the unglazed area with black ice. This is cone 6.

38789727_661956010837941_867310187056830

Edited by Joseph Fireborn

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Kentucky Mudworks Brown Bear is available in a 25# sample bag. I love this clay, along with all of their clays it's just really well made. Easy to form, low absorbency, most  glazes look great, particularly whites and other light colors.

Edit to add Laguna's WC-391/B3 is another alternative, you may be able to find a nearby supplier to save on shipping costs. It has more manganese (4% I believe) and so is slightly darker than the BB. It's also a nice clay, but be sure to have a good vent setup, my self-rigged updraft fan wasn't sufficient so I had to stop using it after 2 time because of the strong smell. Beautiful clay, though.

Edited by NancyAmores

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well could solve prob by applying a black matte to lower third of pot.... like my mugs in "interesting results" in Studio forum:-/

black glaze could be more matte and black by tweaking.....

just saying. Or a black underglaze..

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Standard 710 is the same as 266 but with added grog - I fire it to a hot cone 6 without any bloating on thinly thrown mugs/bowls. It's a really nice clay to throw with! It does react strangely with some glazes so testing is key of course.

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11 hours ago, harleydp said:

Standard 710 is the same as 266 but with added grog - I fire it to a hot cone 6 without any bloating on thinly thrown mugs/bowls. It's a really nice clay to throw with! It does react strangely with some glazes so testing is key of course.

Grog will bump up the peak temp. Is it a coarse grog or fine? I could see 266 being really nice with fine grog. Also, is the grog visible in the fired clay?

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14 hours ago, neilestrick said:

Grog will bump up the peak temp. Is it a coarse grog or fine? I could see 266 being really nice with fine grog. Also, is the grog visible in the fired clay?

It is a fine grog and yes, it's visible in the fired clay. This is from Standard's website about 710: "Gives a reduction-like dark brown color in an electric kiln. Smooth and plastic. Contains manganese and a small amount of fine grog is added. It's good for all techniques. We recommend firing to cone 5."

Here is a bowl I did with 710 leaving the rim and foot unglazed (KY Mudworks Everglade glaze and Amaco Temmoku for the stripe)

IMG_3907.jpg

IMG_3912 2.jpg

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