Jeff Lawrence on sat 19 feb 00
Hello,
All my books except the latest addition ("Chinese Glazes", by Nigel Wood --
a really awesome book) devote a subordinate clause at best to primary clays.
The usually ample discussion of secondary clays make sense - hydrolysis of
feldspar leading to kaolinite etc. as a result of weathering and transport.
The idea of primary clay bugs me because I've found so little description of
it. Hank Murrow stimulated reading on other plastic materials, such as
sericitic rhyolite, hydromicas, etc., which are sometimes referred to as
primary clays, but I'm having trouble finding an overview.
This difficulty leads me to troubling conclusions ... I don't like to be the
one to point an accusing finger, but we all need to ask ourselves some hard
questions. Please look in your heart:
Haven't you ignored primary clays because they are alumina-deficient and
hence "not really clay?"
Haven't you marginalized primary clays because they are mere minority
minerals? Perhaps just a little too diverse?
Please let's disprove these disturbing possibilities -- how about any
bibliographic references that show we've paid the respect due the ur-clays.
anguished in Espanola...
Jeff
Paul Taylor on sun 20 feb 00
Dear Jeff
You are so right.
I think that our pottery materials are industry focused. Even the small
wholesalers make up their bodies with clays from large mines that are
totally dedicated to industrial pottery. The advantage of this is we get the
benefits of their economies of scale. Kaolins and feldspars are so
conveniently abundant and reliable for the industrial processes that
industry has no need to look further.
I am surrounded by small pockets of usable ceramic materials but they need
to be mined ground sieved et all. This is a lot of work and those that do it
usually give up in favor of their back.
Also the rumors of the special qualities of these other clay type
materials are just theories to explain why we no longer seem to be able to
reproduce some of the classical glazes. They may behave no differently to
the materials commonly available.
I would like to get a hold of a kilo of chinese Petuntse, to test the
theories before I start digging up the west of Ireland.
Paul T
----------
>From: Jeff Lawrence
>To: CLAYART@LSV.UKY.EDU
>Subject: Primary clays - minority minerals?
>Date: Feb 20, 2000, 1:37 am
>
>----------------------------Original message----------------------------
>Hello,
>
>All my books except the latest addition ("Chinese Glazes", by Nigel Wood --
>a really awesome book) devote a subordinate clause at best to primary clays.
>The usually ample discussion of secondary clays make sense - hydrolysis of
>feldspar leading to kaolinite etc. as a result of weathering and transport.
>The idea of primary clay bugs me because I've found so little description of
>it. Hank Murrow stimulated reading on other plastic materials, such as
>sericitic rhyolite, hydromicas, etc., which are sometimes referred to as
>primary clays, but I'm having trouble finding an overview.
>
>This difficulty leads me to troubling conclusions ... I don't like to be the
>one to point an accusing finger, but we all need to ask ourselves some hard
>questions. Please look in your heart:
>
>Haven't you ignored primary clays because they are alumina-deficient and
>hence "not really clay?"
>
>Haven't you marginalized primary clays because they are mere minority
>minerals? Perhaps just a little too diverse?
>
>Please let's disprove these disturbing possibilities -- how about any
>bibliographic references that show we've paid the respect due the ur-clays.
>
>anguished in Espanola...
>Jeff
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