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Experiment With Local Blue Clay And Ash Glaze


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#1 Mart

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Posted 28 August 2013 - 04:09 AM

I dug up some soft blue clay (turns red, when fired). I found this clay from the local beach, in shallow water.

It's soft and clean blue color but needs to be cleaned form small rocks. I took few kilos of this stuff with me and some ash form a local fireplace where w had a fire.

 

This is definitely a low fire clay but I have never fired it.

 

So, my plan was to mix it up with ash (unwashed) and test it out. We fire our stuff between 1257-1280 (cone 7-9) in electric kiln.

 

Is this total waste of time?

 

We are also going to fire our ceramic fiber gas kiln soon, maybe I can get better results form reduction?

 



#2 Pres

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Posted 28 August 2013 - 06:26 AM

As with any new glaze, test test test! In this case make certain you protect your shelves well with kiln wash.


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


#3 Marcia Selsor

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Posted 28 August 2013 - 06:47 AM

Not a waste of time. I had a great golden matt ^10 glaze in 1971 that was cherry wood ash and gold art. Your low fire glaze will melt more than Goldart. You may need to add a little kaolin for stiffening.Post result when you fire.
Marcia

#4 Denice

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Posted 28 August 2013 - 08:30 AM

If you fire it to C7-9 you might put the clay in a bisqued bowl to test it.  I have seen low fire clay that practically turned into glass when over fired.   Denice



#5 Wyndham

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Posted 28 August 2013 - 08:58 AM

The blue color comes from the iron not having enough oxygen to turn red. It will likely be a glaze in the order of Albany or Barnard slip. I would look to those old recipes for ideas.

Wyndham



#6 Kohaku

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Posted 28 August 2013 - 09:02 AM

Mart- where are you from? I've seen a ton of this blue clay on the beaches in the Pacific Northwest (Olympic Peninsula). I've been considering a similar experiment... and will be really intrigued to find out what happens with your trials...


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#7 Mart

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Posted 28 August 2013 - 11:58 AM

Mart- where are you from? I've seen a ton of this blue clay on the beaches in the Pacific Northwest (Olympic Peninsula). I've been considering a similar experiment... and will be really intrigued to find out what happens with your trials...

 

 

Different continent, time zone etc. :)

I'll let you guys know, how it works out and I'll try to find out more about the clay too.



#8 Mart

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Posted 28 August 2013 - 12:28 PM

Update
This blue clay is really old and belongs to geological period called Cambrian, which lasted from 541.0 to 485.4 million years ago. Kohaku, it is possible, that Olympic Peninsula was stone throw away in those days. :)

This clay is visible only in northern parts of the country around in Estonia.
As I understand, everywhere else it covered with thick layer of rock and is usually not found in its soft form. Some say it's considered as a small geological "miracle" and visiting geologist usually like to see it. (quick translation from wikipedia) :)

I'll fire this half a billion years old stuff up next week and we will see, how it works out.
Here is a picture of this clay: http://et.wikipedia....nisavi_saka.jpg

#9 TJR

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Posted 28 August 2013 - 12:43 PM

Wow! Beautiful colour. I would say to make a line blend of the two materials to see how they melt. Place inside some bisque bowls to prevent running onto your shelves.

TJR.



#10 jrgpots

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Posted 28 August 2013 - 12:54 PM

Great color.  A quick review on line shows that the clay is  illite with 20% illite smectite and up to 2% pyrite,  a mica clay.  Don't know if that helps.

 

Jed



#11 Kohaku

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Posted 28 August 2013 - 03:39 PM

Yup- that's the same stuff I'm seeing. Gotta love plate techtonics. Good luck... I'm seriously excited to see the pictures.


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#12 Mart

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Posted 06 September 2013 - 08:34 AM

Here are the test results from our tiny down draft gas kiln, we fired yesterday, to cone 10. reduction.

Attached File  IMG_2708_v1.JPG   52.39KB   7 downloads
 
Attached File  IMG_2710_v1.JPG   55.4KB   3 downloads
 
 
A - 3 parts of clay and 2 parts of ash
B - 1 part of clay and 1 part of ash
C - 2 parts of clay and 3 parts of ash
D - 2 parts of clay 3 parts of ash and 1 part of porcelain (slip)
 
I think this stuff needs more time to mature. If I get a chance, I'll use it in local anagama kiln.




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