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high vs low biscuit firing

updated sat 16 oct 04


Janet Kaiser on fri 15 oct 04

You could well be right Lee, but you know, those pesky
industrialists only spend money when it is absolutely necessary.
They have their costs worked out to minute fractions of
pence/cents/whatever and would hardly fire high if it were not
necessary at any point in the process. And I know for a fact that
some work demands high biscuit firing temperatures and much lower
glaze firing. But high - medium - low -- the choice will depend
on all the other contributing factors from the clay used to the
decoration and glaze. I doubt very much that there is a hard and
fast rule for a biscuit temperature and certainly do not think
such a thing is designated by completely by either "fashion" or
"tradition", do you?

High fired biscuit... Well include some tile types just to start
with... Especially if they are bespoke tiles made for swimming
pools or wet rooms! The high biscuit firing ensures they really
are vitrified and/or as hard/sturdy as they are going to get,
whilst the colourful and even gaudy decoration/s (usually with
lead glazes too) will be guaranteed through low glost firing
temperatures whether they are produced using on-glaze,
underglaze, stains, slips or whatever. Whatever method is used to
achieve the required designs/patterns, it is normally using
pretty intense colours associated with low-firing, so strength
has to be achieved some other way...

When talking to someone who is involved in this business
recently, they said that it is sometimes underglaze, but most
often they use coloured glazes painted on and a clear glaze
sprayed over the whole... Something I would not think to do as a
studio potter, so I would really like to watch them working on a
large project to see exactly how it is done. But apparently there
are "trade secrets" which outsiders must not witness... As it
happens, the company may well have to help us to complete the
International Potters' Path. I hope not, but I cannot see us
making a good enough job of the tiles still needed to finish even
half the project! Given our present state of health, I cannot see
that "Phase III" will ever be started, let alone completed under
our "management". But hopefully someone else will continue where
we finished... Fingers crossed!


Janet Kaiser -- not looking forward to the next couple of months
of ever shorter days.

> I believe it is industry that got us bisquing at higher temps.>
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