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low fire glaze absorption, c06

updated sun 26 oct 03


Tricia Messenger on sat 25 oct 03

Hello everyone,
I am stumped. I am using two types of low fire earthenware clays in
my studio from Sheffield and mixing my own alkaline glazes.
The problem I am having is in regards to my red earthenware clay
absorbing the glaze after a c04 bisque. The red clay body is redart,
ballclay and fine silica sand, c06 to c02, absorption at 3.5%. The
white clay, c06 to c02 has ball clay and a non asbestos talc with a
much higher absorption rate of 9.2% . I am aware that the absorption
rate of the clay body is causing the problem, however, is there
anything I can add to my glaze body to make the glaze dry faster?
This would be much simplier than altering the clay body because I do
not own a pug mill and the clay is already stiff to begin with.
In the past I used c06 commercial glazes on these c04 bisque clay
bodies without any difficulty with glaze drying. Now if I dunk or brush
my glazes on the red clay it takes at least 1 hour to air dry. I should
point out that there are no problems with glaze drying on the white
clay. My c06 glazes are mixed to the perfect wet consistancy for
My base glaze formula from James Chappell is:
Gerstley Borate 25.8%
Ferro Frit 3269 41.6%
EPK 32.6%
Vee Gee Gum 1 tsp

Any suggestions would be greatly appreciated.

Marek & Pauline Drzazga Donaldson on sat 25 oct 03

Dear Trish,=20

it seems the bisque is too high for the body, lower the temp to suit =
your glaze.

happy potting Marek