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dandyclay

Once-Fired Unglazed Porcelain

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Hello Wise Members of The Ceramic Arts Community,

I have just started to work with porcelain clay, mostly handbuilding small detailed floral pieces with Miller Clay #550 Cone 10 Grolleg Porcelain (Laguna WC-631), and can find lots of information on bisque firing and glaze firing techniques, however, not so much on how to once-fire unglazed porcelain. I would like to obtain an unpolished, unglazed look with high firing once to vitrification state. Is this difficult to do? Or should I play safe and fire in 2 steps? Please share your great knowledge! I welcome any advice on cone temperatures, timing, cool down techniques, etc. I have a small Paragon Firefly tester kiln.

Thank you so much in advance for any help and advice you can give this newbie :)

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I would think there would be no problem firing once if you are not glazing. Although I use a diamond pad to smooth the surface in the bisqued state of my unglazed porcelain sculpture.

Marcia

 

Thank you for your kind reply Marcia, that's great to know once-fired/single-fired porcelain isn't too tricky to do. I am on a steep learning curve at the moment so your encouragement is very welcome! Thanks also for the diamond pad tip.

Your Saggar Pots and Horsehair and Feathers Collection are so inspiring!

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I agree with Marcia ... I often single fire my porcelain since I seldom glaze it. Just remember that the pieces will need to be supported at high temps whether you bisque or not to prevent warping and collapse. I sand mine with the black wet/dry sandpaper after high firing.

 

If you ever want to get into coloring the florals ...... :D

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I agree with Marcia ... I often single fire my porcelain since I seldom glaze it. Just remember that the pieces will need to be supported at high temps whether you bisque or not to prevent warping and collapse. I sand mine with the black wet/dry sandpaper after high firing.

 

If you ever want to get into coloring the florals ...... :D

 

 

Chris can you refer me to information about supporting unglazed porcelain in the high fire?

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I agree with Marcia ... I often single fire my porcelain since I seldom glaze it. Just remember that the pieces will need to be supported at high temps whether you bisque or not to prevent warping and collapse. I sand mine with the black wet/dry sandpaper after high firing.

 

If you ever want to get into coloring the florals ...... :D

 

Thanks so much Chris, my porcelain firing confidence is increasing with each reply on this wonderful forum :) I'm thinking of supporting the very fragile flower petals with 'Porcelain Prop', also was going to sit the flowers on a ceramic blanket such as Superwool or Kaowool or maybe even porcelain sand? Please may I ask which you think would work best for floral pieces?

And I must say after watching your 'How to Color Clay' lesson, I might just be tempted to add a dash of colour to my next collection! :D

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Dennis Parks book is based on once firing with oil, but it's either glazed or salt fired work that he does primarily. I really enjoyed his book and own it myself. Though the copy I have is somewhat dated I find it to be reliable information that is true enough today as it was when it was written.

 

In wood firing we often try to create a dry surface coated with flashing slips. The dryer this surface comes out the more color it can attain. These pots come out rough to the touch like dry bisque ware. After taking out of the kiln I buff the surface with a 200 to 400 grit paper which makes it feel silky smooth. This is probably one of the most rewarding kinds of pottery for me to fire because it's not only a surprise but it's also a long and difficult process. It takes diligence to not create so much ash in the firing that will coat the pots, melt out and take away all the flashing colors.

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Dennis Parks book is based on once firing with oil, but it's either glazed or salt fired work that he does primarily. I really enjoyed his book and own it myself. Though the copy I have is somewhat dated I find it to be reliable information that is true enough today as it was when it was written.

 

In wood firing we often try to create a dry surface coated with flashing slips. The dryer this surface comes out the more color it can attain. These pots come out rough to the touch like dry bisque ware. After taking out of the kiln I buff the surface with a 200 to 400 grit paper which makes it feel silky smooth. This is probably one of the most rewarding kinds of pottery for me to fire because it's not only a surprise but it's also a long and difficult process. It takes diligence to not create so much ash in the firing that will coat the pots, melt out and take away all the flashing colors.

 

Many thanks for all this great info. and I've been hoping for some once-fired book recommendations, A Potter's Guide to Raw Glazing and Oil Firing is going on my wishlist!

As I'm mostly working with porcelain I also have Jack Doherty's book on my wishlist in the hopes that I might gain some more insights into porcelain firing schedules, etc.

Any other reading-list recommendations on once-firing porcelain are most welcome!

I'm finding English Grolleg a delight to handbuild with - just scared to bits of now putting it in a kiln!! :huh: Must be brave!

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I purchase a clay from Clay Art Center in Tacoma WA called Takamori. It's a porcelain made with 50/50 Grolleg and 6 Tile Kaolins. It's named after a famous sculptor that uses porcelain to make nearly life size figures. It's amazing stuff, that has few of the problems that most commercially produced porcelains have. I don't support my porcelain, but I also don't throw it translucent thin either.

 

I got Dennis Parks' book off ebay or amazon, it was used from a library. It arrived in good condition with no marks or tears. I've read it cover to cover several times now. It only cost me about $20.00 for this one. I've tried to collect as many good ceramic books as possible, most of which I've collected from a local company Powell's Books, CAD Bookstore, Amazon and Ebay and mostly on a used basis.

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