mel jacobson on tue 17 jan 06
this has been published so much i always
hesitate sending again..but, it does not matter.
dan rhodes/by david shaner.
from the book: cone 9,10
oxford spar 48.9
china clay 25.1
dolomite 22.4
whiting 3.5
copyright 1957
mel's variation/2006.\cone 10, 11
depending?
feldspar 11 pounds
china 5.7 lbs
dolomite 5.2 lbs.
whiting 3/4 lbs.
silica 2 lbs.
add rutile and iron
to taste. or add a cup
of temmoku glaze or any
rich iron bearing glaze.
leave out the iron and rutile and you have a pure white glaze.
blue green:
base rhodes32
in a five gallon bucket.
add a quarter cup of chrome
add a quarter cup of cobalt.
this is a very strong glaze.
not to be used on the surface.
you cover this glaze with base rhodes32.
thickness and thinness makes for great variety.
and i use a great deal of hot wax and sharp nails to cut
through the drying glaze.
i make a strong rutile/iron underglaze too.
i also use mel's orange with this combo.
i beat the `mother in law blue` syndrome by adding
chrome to the cobalt.
i always do this...it makes things a rather nice aqua (depending.)
blue customers will always take blue/green instead of blue.
mel
if you use neph sy with dolomite and china clay
you can drop this to cone 9. so. the shop glaze
with neph sy is just a variation...there are hundreds of others.
i just love dolomite. simple glazes...four or five ingredients.
from mel/minnetonka.mn.usa
website: http://my.pclink.com/~melpots3
Eric Suchman on sat 21 jan 06
What would I change or alter to get the recipe to ^6?
On Jan 17, 2006, at 9:07 AM, mel jacobson wrote:
> this has been published so much i always
> hesitate sending again..but, it does not matter.
>
> dan rhodes/by david shaner.
> from the book: cone 9,10
> oxford spar 48.9
> china clay 25.1
> dolomite 22.4
> whiting 3.5
> copyright 1957
>
> mel's variation/2006.\cone 10, 11
> depending?
>
> feldspar 11 pounds
> china 5.7 lbs
> dolomite 5.2 lbs.
> whiting 3/4 lbs.
> silica 2 lbs.
> add rutile and iron
> to taste. or add a cup
> of temmoku glaze or any
> rich iron bearing glaze.
> leave out the iron and rutile and you have a pure white glaze.
>
> blue green:
> base rhodes32
> in a five gallon bucket.
> add a quarter cup of chrome
> add a quarter cup of cobalt.
> this is a very strong glaze.
> not to be used on the surface.
> you cover this glaze with base rhodes32.
>
> thickness and thinness makes for great variety.
> and i use a great deal of hot wax and sharp nails to cut
> through the drying glaze.
>
> i make a strong rutile/iron underglaze too.
>
> i also use mel's orange with this combo.
>
> i beat the `mother in law blue` syndrome by adding
> chrome to the cobalt.
> i always do this...it makes things a rather nice aqua (depending.)
> blue customers will always take blue/green instead of blue.
> mel
> if you use neph sy with dolomite and china clay
> you can drop this to cone 9. so. the shop glaze
> with neph sy is just a variation...there are hundreds of others.
> i just love dolomite. simple glazes...four or five ingredients.
> from mel/minnetonka.mn.usa
> website: http://my.pclink.com/~melpots3
>
> ______________________________________________________________________
> ________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.
Steve Slatin on sun 22 jan 06
Eric --
Others may disagree with this rather simple
analysis, but I'd say you probably can't get
this glaze to work at ^6.
As Rhodes wrote it, it's somewhat low in
silica and high in alumina to begin with.
The melters are tilted towards the less
powerful fluxes. The Si/Al ratio is quite
low, 4.35. It's a matte glaze because
it barely melts as it is at ^10, so the
surface never 'heals' itself smooth.
Adding more of the same fluxes (a crude
but often successful first step) will further
lower the silica level. Likewise adding
a boron-rich material to the existing recipe.
Neither of these usual first steps will
work because they push the glaze
in the wrong direction in ways other then
melt temperature.
Switching from feldspar to Nepheline syenite
as a primary ingredient (almost 50%!) of the
glaze will substantially raise the COE, possibly
giving you a melt at ^9, but maybe giving you
a defective glaze as well. (Very likely
crackling and, with an SI/Al ratio of about
3, not likely a good glass formation.)
Going over 50% of nepheline syenite isn't generally
good, and many folks report settling problems.
So here you are at ^9 trying to get to ^6,
and there's no space for more feldspar or
equivalents, you need to add Si to get a
good glass surface, which you can't do
without LOWERING the melter concentration,
you've still got the problem of surplus Al and
so on.
My belief is you can't get there from here. There
are plenty of ^6 glazes that are matte or semi-matte
to begin with; check the archives and start with
something that already works at ^6 and you'll
much more likely get a good result.
Best wishes -- Steve Slatin
Eric Suchman wrote:
What would I change or alter to get the recipe to ^6?
On Jan 17, 2006, at 9:07 AM, mel jacobson wrote:
> this has been published so much i always
> hesitate sending again..but, it does not matter.
>
> dan rhodes/by david shaner.
> from the book: cone 9,10
> oxford spar 48.9
> china clay 25.1
> dolomite 22.4
> whiting 3.5
> copyright 1957
>
> mel's variation/2006.\cone 10, 11
> depending?
>
> feldspar 11 pounds
> china 5.7 lbs
> dolomite 5.2 lbs.
> whiting 3/4 lbs.
> silica 2 lbs.
> add rutile and iron
> to taste. or add a cup
> of temmoku glaze or any
> rich iron bearing glaze.
> leave out the iron and rutile and you have a pure white glaze.
>
> blue green:
> base rhodes32
> in a five gallon bucket.
> add a quarter cup of chrome
> add a quarter cup of cobalt.
> this is a very strong glaze.
> not to be used on the surface.
> you cover this glaze with base rhodes32.
>
> thickness and thinness makes for great variety.
> and i use a great deal of hot wax and sharp nails to cut
> through the drying glaze.
>
> i make a strong rutile/iron underglaze too.
>
> i also use mel's orange with this combo.
>
> i beat the `mother in law blue` syndrome by adding
> chrome to the cobalt.
> i always do this...it makes things a rather nice aqua (depending.)
> blue customers will always take blue/green instead of blue.
> mel
> if you use neph sy with dolomite and china clay
> you can drop this to cone 9.
Steve Slatin --
Le réalité et toi, vous ne vous entendez pas, n'est-ce pas?
---------------------------------
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Ivor and Olive Lewis on mon 23 jan 06
Dear Eric Suchman=20
You ask <<...What would I change or alter to get the recipe to ^6?... >
An interesting question, given the nature of Mel Jacobsen's reply which =
you quote. I take it you understand the reasons for Mel's first =
modification because this tells us a lot about the nature of the =
original formulation.
My first thought is"Do you wish to change the original finish, which is =
described as "Stony, smooth mat,very opaque and given the name 'High =
Alumina Mat' ?"
Before going further I would like to have a look at the Seger =
Formulation for the original. Are you , or is anyone else, able to =
supply this information.
Best regards,
Ivor Lewis.
Redhill,
South Australia.
Ivor and Olive Lewis on tue 24 jan 06
Thanks Steve Slatin for your summary of the attributes of this =
concoction. I am surprised it is called a glaze. Much more like a =
vitreous slip or engobe loaded with Calcium and magnesium oxides which =
have nothing to dissolve into to work their magic
One suggestion I would make is to put it on raw clay, bisque, then apply =
an overcoat of something else that is a well balanced high silica recipe =
before firing to cone 6. There might be some pleasant surprises coming =
from the kiln.
Best regards,
Ivor Lewis.
Redhill,
South Australia.
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