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Terra Sig Burnishing


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Hi all,

 

Glad to say I've been getting some great results in my saggars lately, but I'm unclear on a couple details about TS and burnishing

I haven't done much with the TS / burnishing yet, but yesterday I tried it with good results as well.

 

I've seen all the YouTube vids on TS and burnishing, but I haven't heard anyone actually say if they burnish the greenware and then bisque it or if they just go direct into the saggar or raku after burnishing. I guess it's assumed one knows such.

 

I've been using TS on my work before I bisque them just for color. I bisque to assure they hold up in the saggar firing.

 

So, do most people just throw, apply TS and burnish and straight to the kiln for raku/horsehair/saggar?

Or are the bisqueing after the TS treatment?

I would think that the sheen would fade in a bisque.

 

Looking for some concrete answers before I load my next bisque...

 

Thanks,

 

Rex Johnson

www.earthbasedceramics.com

 

 

 

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I may have found my answer (partially) thanks to Wiki:

 

Terra sigillata is usually brushed or sprayed in thin layers onto dry or almost dry unfired ware. The ware is then quickly burnished with a soft cloth before the water in the terra sigillata soaks into the porous body. The burnished ware is allowed to dry again to remove the added moisture and biscuit fired, often fired to a lower than normal bisque temperature of approximately 900 Â°C. Higher firing temperatures tend to remove the burnished effect in the clay surface.

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That quote is not how I do it.

I apply the TS to bone dry (Smoothed) clay. Contrary to Wiki, let it dry and burnish with a soft sponge. It dries almost immediately on bone dry clay.

You can see a demo on a dvd clip. I will find it and post it. You can reapply a second coat and burnish again.

Be careful not to apply too think or it can flake off.

Bisque to ^09 max ^08 to avoid losing the sheen. I saggar fire to 1650 F.

 

Marcia

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yep, apply the terra sig to bone dry greenware.i do two coats, no more.   then i buff it gently with a soft cloth.   the microfiber cloth they sell to wash cars with works well.  I don't consider it burnishing because to me that implies using a polished stone with quite a bit of pressure.  its a gentle buff and the shine comes up quickly.  we bisque to cone 06 and the shine remains.    rakuku

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  • 2 weeks later...

I'm having pretty good results 'polishing' with a plastic bag now.

That said, I test-bisqued a couple pieces to appx 1700-1750 in my raku kiln and lost some sheen.

Would there be possibly be an effect if there was more or less reduction in the bisque affecting the sheen?

I have a large load of bowls polished and ready that I intend to bisque in my bigger gas kiln (appx 26 cu ft downdraft).

Hoping for the best.

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rex, if you read the post made by marcia and watch the video, the next step is READING the comments below.  she tells you exactly what temperature to bisque properly.  you have exceeded that temp by hundreds of degrees.  failure is the result.

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rex, if you read the post made by marcia and watch the video, the next step is READING the comments below.  she tells you exactly what temperature to bisque properly.  you have exceeded that temp by hundreds of degrees.  failure is the result.

 

..excuse me, I have watch the video and read the comments.

Cone 08-09 is 1693-1751F

There is also also a comment from another contributor saying they fire at cone 06 (1830F) as well...

 

I fired appx 1750F is right in the range suggested, so no, you are mistaken...

You might want to read your cone chart before commenting.

 

My question is about the kiln firing atmosphere.

 

 

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Darling Marcia!

A friend told me about her arduous work with TS, which pretty much put me off for a few years, but I was curious to see your set-up.

By the time you rolled that last pot in the horsehair, I noticed a huge grin on my face! You've dispelled all my fears. The separation technique and foam buffing - the fabulous results! Wonderful!

Thank you,

Rae

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I'm referring to any change there might be of the sheen (polished) TS if there was more or less reduction, if at all.

In other words, I'm just trying to factor out anything that might reduce the polished TS during the bisque.

I had some loss in the polish after my test bisque in my raku kiln.

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attachicon.gifgreenblushsmsaggar.jpgattachicon.gifgreenblushsmsaggar.jpgThat quote is not how I do it....

Bisque to ^09 max ^08 to avoid losing the sheen. I saggar fire to 1650 F.

 

Marcia

Rex, it looks like your bisque at 1750F is right at the max recommended by Marcia to avoid losing sheen, you could fire a cone lower.

 

I think the amount of reduction of oxygen you might get by bisqueing with gas is negligible.

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