iandol on mon 10 sep 01
Dear Althea Vail,
The notion of using a kiln wash on bats is all pervasive in the ceramic =
arts and pottery text books. And I suppose most people suffer from the =
ways in which it will behave to cause problems.
So I pose the question "Why do you use it"
If you dry foot each pot, have glazes which do not over liquefy and =
dribble down the foot or detach from appendages then there is no need to =
use kiln wash. If you have trust in your materials and techniques then a =
dusting of 100# Alumina sand on your shelves will give you good results. =
It is highly refractory, does not have the hazards of silica, is easily =
sanded from footrings and allows the pots to shrink without catching on =
the shelves. Applied with care, it is the best material to use.
In a teaching situation where student work may not be trust worthy then =
a layer of kiln wash is advisable. You sound as though you have =
graduated beyond that to a professional situation.
All the best,
Ivor Lewis. Redhill, South Australia
iandol on thu 13 sep 01
Dear Des Howard,
Under those circumstances I would do likewise. I applaud your =
elimination of Silica from the equation. But in an electric kiln or with =
aspirated gas and natural draught, a good dusting of alumina sand works =
well.
I have seen a thick coat of kiln wash, used on Saltglazing shelves, made =
using flour as a binder being used and combed into patterns. Salt was =
able to penetrate the gaps under the pots and create a negative replica =
of the pattern. A very effective form of decoration.
Must be a good clay to withstand cone 12!
Best regards,
Ivor.
Des Howard on thu 13 sep 01
Ivor
We use blower assisted gas burners in our kiln,
even with vacuuming the kiln out before setting
up a firing we can still get rubbish in the fired ware,
using a dust or sand as a setting medium in
our firing environment is a no-no.
The kiln wash used is
90% zircon flour
10% kaolin
Very thin wash.
No silica!
Even with kiln wash we can get severe plucking
on large, heavy items, due to the degree of
vitrification from our usual Cone 12 firings.
Fired refractory cookies, single use grog/raw clay cookies
or bisque cookies of body clay minimise this problem.
Des
iandol wrote (in part):
> So I pose the question "Why do you use it"
>
> If you dry foot each pot, have glazes which do not over liquefy and dribble down the foot or detach from appendages then there is no need to use kiln wash. If you have trust in your materials and techniques then a dusting of 100# Alumina sand on your shelves will give you good results. It is highly refractory, does not have the hazards of silica, is easily sanded from footrings and allows the pots to shrink without catching on the shelves. Applied with care, it is the best material to use.
>
--
Des & Jan Howard
Lue Pottery
LUE NSW 2850
Australia
Ph/Fax 02 6373 6419
http://www.luepottery.hwy.com.au
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