hal mc whinnie on wed 19 jul 00
CERAMIC GLAZE COURSE
LESSON FOUR PART ONE
RAKU AND LOW FIRED GLAZES
If we look at the attached collection of raku glazes we can see that they
are basically a balance of:
TWO ELEMENTS, WHICH ARE A 60-30, BALANCE OF TWO FRITES OR A 50-50 BALANCE OF
FIRST OR COLEMANITE
In addition to these two main elements other chemical have been added in
small amounts
1] For color effects
Copper oxide
Chrome oxide
Selenium
Vanadium
Cobalt carb
Red iron oxide
Manganese
2 for surface qualities
Silica
Epk
Lithium carb
I have discovered that one can turn these raku glazes into useful cone 04
oxidation glazes by a simple substitution of nephlene syneite for the
colemanite or borax. Were there are only frits substitute neph syn for one
of them.
This simple substitution can be done without calculation because the neph
syneite contains more silica then the colemanite or the borax and this
raises the, melting point of the glaze from raku to cone 04
I start with the raku glaze because of their simple structure one can see
more clearly the balance of the glaze elements within the basic chemical
formula.
SOME RAKU GLAZES FROM THE UNIVERSITY OF MARYLAND
Raku green
Frit24 60
Frit 25 18
Flint 21
Copper oxide 3
Raku yellow
Frit 24 60
Frit 3124 18
Flint 21
Chrome oxide 1
Raku black
Frit 24
Flint 30
Epk 4
Copper carb 16
Raku yellow
Red pb frit 85
Flint 15
Selenium 6
Red raku
Borax 20
Frit 3124 80
Bentonite 3
Selenium 6
Clear white raku
Frit 25
40
Colemanite 45
Flint 5
Epk 10
Yellow raku
Colemanite 50
Borax 50
Vanadium 6
Copper red black
Borax 20
Frit3124 80
Epk 5
Copper oxide 5
Behrens raku blue
Frit 25
Frit 3124 26
Lithium carb 10
Epk 6
Flint 14
Red iron oxide 2
Green chromium 1
Plum white raku
Borax 40
Colemanite 40
Epk 10
Flint 5
Whiting 5
Cobalt one half
Manganese 2@
Copper red gold raku
Borax 20
Frit 3134 80
Epk 5
Copper oxide 5
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