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Hi all,

 

I've posted about this local clay body before and I'm checking with the forum to get ideas on trouble shooting another issue. I'm firing to cone 05/04. The body itself is a beautiful lowfire body but after the bisque it gets a white scum on the surface . I'm not sure what it is that's causing the whiting but  I think that the clay body would be gallery quality were it not for this blemish. I have sanded the surface after firing and the white can be removed. Obviously this is not a solution but it confirms that there is a beautiful clay body just below the surface. Any ideas of how I can resolve this kind of issue in the clay refining stage?

I have links for some images below

 

https://drive.google.com/file/d/0BwDDXHDlS0HGMHVKZVE1VDJuNkUzY2JIbXFFZ2NwMWJ6RHR3/view?usp=sharing
https://drive.google.com/file/d/0BwDDXHDlS0HGa2Q1LXFkMy1sLVlMaGJBdkE3djN5RUtxNnhJ/view?usp=sharing
https://drive.google.com/file/d/0BwDDXHDlS0HGMjZQZ1kzb1JnQklZbzc1WExhM1Q2VWVUVjFz/view?usp=sharing
https://drive.google.com/file/d/0BwDDXHDlS0HGSjFXa2MycWRLcVZwVlJPNWxMM0VYTjlwQ0tn/view?usp=sharing

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Probably soluble salts.  I know some clay bodies have barium added to mitigate this.

Could also be from a lack of oxygen during the bisque.  Sometimes my red clay gets like that if I fire too fast with not enough air.

Edited by liambesaw

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Perfect thanks for the info!

 

secondary question for the 300lb that I've already processed and have been aging for several months lol. Any ideas of what i might be able to do to get rid of that after bisque? or do i just need to bite the bullet and start over?

I don't have a pugger all this clay is being dried in an inverted perforated metal table outside with sheets for a liner. Winter is just getting started here in southern Utah.

Edited by Mullins Pottery
needed to add a bit

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3 minutes ago, Mullins Pottery said:

Perfect thanks for the info!

 

secondary question for the 300lb that I've already processed and have been aging for several months lol. Any ideas of what i might be able to do to get rid of that after bisque? or do i just need to bite the bullet and start over?

I don't have a pugger all this clay is being dried in an inverted perforated metal table outside with sheets for a liner. Winter is just getting started here in southern Utah.

Does the scum stick around after the glaze firing?  I suppose it probably does since your clay is a lowfire one.  It doesn't on my cone 6 stuff.

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