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Accidentally marbled ^6 and ^10 clay ...

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Hello clay hive mind!

I was happily making some planters and cups last week out of clay I'd marbled. I thought I'd used Laguna Speckled Buff and B-Mix (50/50), but no ... turns out it was Speckled Buff and Soldate. ugh - I'd grabbed the wrong bag. :wacko: 

Is my bone dry greenware trash? Can I fire at Cone6 and get some use out of them? I'm thinking that the cups are NOT food safe (plus bonus: they likely won't hold hot liquid), but can I use them as planters? Some folks say that porous planters are best anyway ... (trying to find some silver lining here).

I'd love to hear anyone else's experience or advice.


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hope it was not a lot of your clay inventory.  toss it or use the clay for making molds that you would cast in plaster.  or around a plaster mold being made with cottles.    or trash it somehow.

firing a cone 10 clay to cone 6 would be just as waterproof as a paper bag.   firing cone 6 clay to cone 10  might make you very sorry about the kiln.   toss it without another thought.

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I think planters would be okay but they won't be super durable as the blended clay won't be mature at cone 6. If you use a plastic pot and saucer inside the planters you wouldn't have to worry about moisture absorption leaving stains on the clay from soil / fertilizer. I wouldn't leave them outdoors during times of freezing weather though. Just put a hole in them so nobody uses them for cups down the road.

Welcome to the forum.

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On 8/9/2020 at 3:52 PM, Sezhoo said:

I'd love to hear anyone else's experience or advice.

A dozen or so years back a colleague was making small ~4 inch diameter bowls with thick and nearly vertical walls.  She bought a half ton of cone 5 b-mix to use at school.  after one semester on cone 5 firings, the studio switched to firing everything at cone 10 reduction.  She continued to use the cone 5 B-mix to make her bowls and fired them in the cone 10 kiln.  [She also used the studio cone 3 oxidation glazes on her ware;]    She had no failures, none!  The geometry of the ware pieces allowed her to obtain success with the "over firing" conditions; the stresses were not enough to cause observable warping.  

I use various commercial clay bodies from cone 04 to cone 10 (and wild "dirt") deliberately mixed or layered over standard cone 10 clay bodies and have not yet achieved any disasters (five + years).  Before making big items, I test small pieces to see what happens.  

As to bloating, I use cone 5 b-mix slip as a thick exterior coating on bowls and mugs and see no evidence of the bubbling or gassing from the b-mix.  Cone 5 b-mix fired to cone 10(R) is not fluid enough to be a glaze and the edges on the slip applications resembling meringue are still crisp appearing.

My suggestion is to make some "test" pieces that you would expect to deform, and fire without glaze, see what happens, and go from there.   


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There are happy accidents, so there should also be happy accident "test test tests"!

I haven't been able to find 2 clays worth marbling with the same shrink. Kinda realized I was being too....too.... worried?

So my first go is Standard 101 which is a 02-9 clay, and my local "red river" clay which turns to a reddish metallic blob of corey carbon at Cone 8. Fitting to fire it to around cone, hell, I don't even know I've never put a conepacks in the kiln in my vase space! 

Best put it on a cookie!

What is better than the smell of caution in the wind?

Besides any kiln at bisque temps, mmmmmm, is there a smell that makes you happier than that smell of serendipity?



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Thanks everyone! I'm considering two avenues: firing a piece at cone 10 and hoping it doesn't puddle  (@Sorcery, love the "smell of caution on the wind" lol) -- definitely a cookie for testing, and firing another at cone 5 and testing after with saucers as suggested by @Min. Neither of those kilns are mine, of course - both are commercial studio kilns, so I'll be sure to notify the staff.

Thanks again for the welcome! I'll give an update once the tests are tested. 


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  • 3 weeks later...
On 8/12/2020 at 1:24 AM, Sezhoo said:

caution on the wind

I posted this pic and got a special order in one day! Woot woot!

Too bad I have no more 101 and the last batch of Red River Clay was way sandier!

More wind! More Caution!

I hate being on the hook for special orders!

Did throw a cone pack in my "vase space"/under the lowest shelf...about a cone 4. 

These went bold up in cone 8 land, sideways on cooooookies.

More good news? My neighbor built a pergola and dug up some clay I use for glaze. Went and fetched 4 full buckets today! Score.

I hope you have had such good fortune!





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