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terracotta ^03-^02 .... was:glazing ^05 earthenware

updated tue 24 may 05


sincultura13 on mon 23 may 05

I'm so glad this is being discussed! There's is little information
on fuctional earthenware on the net (when compared to cone 6) and
post like this one, by Joyce Nagata, give me hope and tell me that
is a road worth pursuing...

I'm trying to understand the logic behind ^03 bisque/^05 glazing...
as opposed to ^04 bisque/^04-^03 glazing which is what I'm doing now.

I was told to bisque lower (^08-06) and Glaze ^03-^02 to make the
ware stronger... It made sense to me since higher temp also means
the glaze will hold more Si/Al in it, right? I was thinking about
glaze fit and harness... I didn't of absorbtion, because I kinda
always thought it was going to be high anyway...

So to say the least, getting a 3% absorbtion on a low fire body is
very appealing to me... How do I go about choosing the right clay
body to do this?

Is there any benefits of ^03 bisque/^05 glazing other than being
able to use commercial glazes?

My way of working is still not set, so I'm willing to adapt (tweak
my glazes to a different temp/change body)... specially if it means
that result is a more consistent and durable functional ware...

BTW, I sometimes glaze the bottom of my pots, but don't if I don't
have to because they tend to slide on some smooth surfaces...



--- In, Joyce Nagata wrote:
> If you are firing terracotta earthenware and you bisque hot....I
bisque to
> ^03-02 you should find that there is very little absorbtion after
glaze firing.
> Make shrinkage bars and do absorbtion tests at various cone up the
the limits
> of the upper reaches of your clay. My work has an absorbtion rate
of less
> than 3%. You can then safely glaze as you would for higher temp.
work. It
> will require changing the viscosity of your glaze, mix it up
thicker, because it
> will be harder to get the glaze on the work. If you are making
> work this is important however. It also increases the strength of
the work as
> the clay is denser and depending on the clay flux, virtually
eliminates crazing
> of the glaze. I run both tin glazed and clear glazed work thru
the dishwasher
> and microwave with no problems ever for the last 10 years. It
does require
> testing and like any work that you sell to the public, test,
subject to stress
> conditions, and retest periodically.