brian
New Member
Posts: 5
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Post by brian on Oct 7, 2017 10:48:25 GMT -6
Hi, I have been having problems with my current porcelain having lots of iron specs in it. Can you recommend a nice throwing porcelain, and where do you buy it from? Thanks.
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Post by tileman2 on Oct 7, 2017 16:01:04 GMT -6
Brian:
Coleman porcelain is the standard and widely used for crystalline. Coleman is a pure grolleg based body, with macaloid used as a plasticizer. So look for a grolleg based body, most makers label it as such. If you are getting iron specks, a grey cast, or tan cast: then ball clay/s have been added for plasticity. Kaolin is naturally low in iron and magnesium: so any spots or color hues suggest ball clay additions which commonly have higher iron and magnesium levels.
The purity test is simple: fire a test bar unglazed to your peak temp: if it is anything but pure white, then it is not pure porcelain. If you fire in reduction, pure porcelain will have a buff/cream tint due to the natural titanium content of kaolin. So test your choice first before you invest much time making pieces.
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gczop
Full Member
Posts: 202
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Post by gczop on Oct 9, 2017 8:16:42 GMT -6
Brian:
For example, a few off the shelf cone 10 porcelains: Standard Ceramic 257 and Troy( cone 10+), Laguna 550 and 570( cone 10+).
Some favor porcelain slip over B Mix 10(Laguna), B Mix wood fires hotter.
My guess is most nice throwing porcelains are custom made.
Gordon
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