Arturo M DeVitalis on sat 5 sep 98
Within the last two months someone posted a glaze "Blatant Blue" and
"Blatant Green"....can anyone resurrect this receipe for me? TIA
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Paul Lewing on sun 6 sep 98
Blatant Blue
Custer 27
Whiting 19
Ball Clay 20
Silica 32
Cobalt Ox. 2
I've never seen a glaze called Blatant Green, but I imagine if you cut
the cobalt down and added chrome to this recipe, you'd get a pretty
bright green. I used to use, back when I was using Blatant Blue, a
glaze I called Gang Green. It was pretty much like that.
Paul Lewing, Seattle
Toni Hall on mon 7 sep 98
Paul Lewing wrote:
>
> ----------------------------Original message----------------------------
> Blatant Blue
> Custer 27
> Whiting 19
> Ball Clay 20
> Silica 32
> Cobalt Ox. 2
>
> I've never seen a glaze called Blatant Green, but I imagine if you cut
> the cobalt down and added chrome to this recipe, you'd get a pretty
> bright green. I used to use, back when I was using Blatant Blue, a
> glaze I called Gang Green. It was pretty much like that.
>
> Paul Lewing, Seattle
Paul,
Can you tell me some more about this glaze. Gloss or matt? Cone ? Running?
Best for electric or reduction? thanks a lot. Its title sounded interesting.
Toni
David James on mon 7 sep 98
>----------------------------Original message----------------------------
>Blatant Blue
>Custer 27
>Whiting 19
>Ball Clay 20
>Silica 32
>Cobalt Ox. 2
>
>I've never seen a glaze called Blatant Green, but I imagine if you cut
>the cobalt down and added chrome to this recipe, you'd get a pretty
>bright green. I used to use, back when I was using Blatant Blue, a
>glaze I called Gang Green. It was pretty much like that.
>
>Paul Lewing, Seattle
WHAT CONE PLEASE, REDUCTION OR OX??
Dave James
Durban
South Africa
Ron Roy on tue 8 sep 98
I can't resist the urge to counteract the comment about making a glaze from
scratch being a bonehead move.
Just using this glaze as an example - here is what you will learn from the
molecular formula - and how you could alter this glaze to fit your
circumstances.
First - this is a cone 10 glaze.
The ratio (silica to alumina) is 10.23 which means it's probably a shiny glaze.
The CaO is oversupplied but there is plenty of alumina and silica so it's
probably a fairly durable glaze.
The expansion is on the low side so it probably will not craze on most
porcelains. On stoneware bodies which develop cristobalite - as many of the
bodies in current use do - this low expansion can lead to dunting and/or
shivering.
I have calculated the original glaze and then a second one with a higher
expansion. To find out something about the expansions of the clay bodies
you use make up the first one (#1 = the original) and my revision with a
higher expansion and call it #5. Never mind the cobalt - it will just make
it more difficult to see any crazing. You can then make up #2, #3, #4 and
find out where, if any, the crazing starts on the different bodies you use.
Once you know that you can make an intelligent choice about which glazes
will work on which clays you use.
#1 (the original slightly modified to total 100)
Custer...............28.0
Whiting............19.0
Old mine #4 - 20.0 (SGP#1 will give the same result as will many ball clays.)
Silica.................33.0
Total...............100.0
Ratio - 10.33
Expansion - 428.36 (lower)
#5 (#1 modified to have a higher expansion but using the same oxides - it
will be more shiny and may even run a bit - it is more durable because it
is a balanced glaze.)
Custer...........52.0
Whiting........18.0
Old Mine...... 6.0
Silica............ 24.0
Total...........100.0
Ratio - 10.12
Expansion - 534.27 (higher)
How to get #3: Custer: 28.0 + 52.0 divided by 2 = 40.0
How to get #2: recipe #1 plus recipe #3 divided by 2
How to get #4: recipe #3 plus recipe #5 divided by 2
You will always know if you have done the math right if each recipe totals 100.
Lets say #3 crazes on your clay body but #2 does not - even after freezing
and dipping in boiling water - you can be pretty sure that would be the
right one. Of course you can get an even finer picture by making the glazes
between #3 and #2.
The larger the pot or test tile the better for evaluating fit.
When I analyse a potters glazes I usually find a wide variation in
expansion between their glazes. It is even so with the glazes I have used
over the years. It is one of the problems with "finding" glazes and not
having a way to check or adjust them. It seems to me this kind of
information should be of concern to anyone trying to make serviceable ware
and avoid losses due to poor fit of clay and glaze.
>----------------------------Original message----------------------------
>Blatant Blue
>Custer 27
>Whiting 19
>Ball Clay 20
>Silica 32
>Cobalt Ox. 2
Ron Roy
93 Pegasus Trail
Scarborough, Ontario
Canada M1G 3N8
Tel: 416-439-2621
Fax: 416-438-7849
Web page: http://digitalfire.com/education/people/ronroy.htm
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