Khaimraj Seepersad on mon 30 oct 00
Good Afternoon , to All ,
Folks ,
before this gets confusing . I am responding to using
coils to hand build with , not throwing .
I then go on to speak of the fired body having used two
types of grog .
In handbuilding , adding different %s of different
sized grog - say 10 % 60 / 80 mesh , 20 % + 100 mesh ,
and 30 % -200 mesh ., will enable a body to build better
and taller . Think of spacing , maybe cement plus gravel
mix as opposed to mortar.
This is also what allows bonsai pots or Egyptian paste to
resist warping during drying and firing.
Handbuilding is facilitated by a well grogged , low plasticity
body , but the sticky , wet nature of the earthenware clay
is what allows the coils to adhere easily .
Khaimraj
Ivor Lewis asked -
Can someone explain to me why adding grog to a clay is the answer. What
>qualities are being altered?
>
>As I understand it, none plastic materials add nothing to the strength of a
>plastic clay, they do not enable higher pots. They may even reduce
>compressive strength and reduce the ultimate height to which any pot can be
>built. To increase the ability of a clay to withstand forces which cause it
>to distort, shrink or crack due to excessive shrinkage it is necessary to
>remove water.
snip
-----Original Message-----
From: Khaimraj Seepersad
To: CLAYART@LSV.CERAMICS.ORG
Date: 30 October 2000 7:39
Subject: Re: Coiling & throwing large pots
snip
>Self grog works very well here from as low as 900 to
>950 deg.c . So there maybe self fluxing taking place
>early o'clock .
>This clay also has some mica content .
>Hope this helps ,
>Khaimraj
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