Michael Wendt on tue 2 sep 08
First, I admit that I am not a porcelain guru.
That settled, The clay body I make is the classic
Alfred recipe except I use Helmer Kaolin, a
sedimentary clay that is primarily kaolin particles
from fine to very fine with small amounts of
associated montmorillinite and tubular halloysite.
I have see the scanning electron microscope images
of Helmer and have it from no less authority than
Michael Grutzek, U of Penn materials science that
the x-ray diffraction analysis shows Helmer is
primarily kaolinitic in structure.
The Alfred recipe I use is modified to the following:
Helmer 143
Ballclay 7
Custer Feldspar 38
A-270 Nepheline Syenite 38
200 mesh silica 75
V Gum-T 0.7
DRA 10C Polymer 1.0
Water 60
This body is very vitreous, translucent and rings
like a bell at cone 10. Lots of people all over the
USA order it as needed and use it for regular clay
as well as wood fire and salt.
Green strength is very high.
We also defy every convention mentioned by all
the other porcelain users.
We force dry the items on an air intake to the
central heating and air-conditioning unit that runs
24/7.
We make attachments without scoring or slipping.
This clay is great for sculpture and handbuilding too.
I have done large handbuilt platters, complex sink
parts, tile and even busts over mandrels.
Finally, we bisque only to cone 08, and find it
works better than 04 where the clay won't absorb
enough water to glaze easily.
Down side for white purists:
Helmer contains around 1% colloidal iron and some
titanium so if you dearly want snow white clay,
this is not for you.
Bottom line,
some bodies can deliver both porcelain like
characteristics of smoothness, reasonable white
color and translucence while still performing more
like a B-Mix stoneware body.
Regards,
Michael Wendt
Wendt Pottery
2729 Clearwater Ave.
Lewiston, Id 83501
U.S.A.
208-746-3724
wendtpot@lewiston.com
http://www.wendtpottery.com
http://UniquePorcelainDesigns.com
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