Lili Krakowski on thu 3 jan 08
Gina, I am not quite sure what you are doing.
You are using a clay body that I assume you have tested at the firing temp,
and method you want.
You now want to coat it with white slip. And the porcelain body clay you
have pounded and slaked into slip is cracking and peeling.
Why are you not using a regular slip?
White slips are made up of ball clay (40-60 parts) kaolin (60-40 parts) --in
inverse ratio to the other clay.
Other ingredients can include feldspar (up to 20 parts), flint (up to 20
parts, Zirconium opacifier 5 parts, borax 5 parts, bentonite of gum if
desired.
Loree slip (named after the potter who made it up) is 5% borax, 14% Ferro
frit 3124, 14% Neph Sy, 24% ball clay, 24 % kaolin and 19% flint.
More slip recipes in PMI Vo.I, Number 1, Winter 1998.
There are some recipes out there meant to be applied very thick, for
texture. I must have a recipe someplace but where?
Your slip must be coordinated with your clay body--i.e. shrink at it does,
same amount--and it must be applied when the pot is the right dryness.
Proportions of materials for application on leather hard, greenware, and
bisque differ. Rhodes has a good chart on that.
But you have to test. I have used all the slips I mention above on
leatherhard clay.
Lili Krakowski
Be of good courage
Ron Roy on sun 6 jan 08
Most slips that are applied to green or bisque will need to be
deflocculated - especially if they are applied thickly.
Lots of advice about defloccing in the archives - or let me know and I'll
send directions - the way I do it.
RR
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Lee Love on mon 7 jan 08
On 1/7/08, Ron Roy wrote:
> Most slips that are applied to green or bisque will need to be
> deflocculated - especially if they are applied thickly.
>
I have recalculated Rhodes crackle slip for bisque here in
Mashiko, but it doesn't crackle. If I add some bentonite, would that
help it shrink and crackle?
I have always thought using this slip under a clear glaze is
a good way to get the crackle look of a crazing glaze, but with a
smooth surface.
--
Lee in Mashiko, Japan
http://groups.google.com/group/ClayCraft
"Men are born ignorant, not stupid. They are made stupid by
education." -- Bertrand Russell
Ron Roy on tue 8 jan 08
Sometimes adding bentonite will make a slip stronger - up to a point. The
problem will be in controlling the shrinkage so it does not fall off.
I have never done it but I would try ball clay first as it will be easier
to control from batch to batch.
I have some experience getting that effect spraying sugar water on powdered
glaze on a horizontal surface - the more water the more "crazing" happened.
You may be able to find one of my snow plates to see the effect - look for
it on the digital fire web site.
You may find spraying the slip after it's on the pot with something to get
it to crack up.
You can google Ron Roy but you have to wade through Ron Roy the childrens
book author to find my pots.
RR
>On 1/7/08, Ron Roy wrote:
>> Most slips that are applied to green or bisque will need to be
>> deflocculated - especially if they are applied thickly.
>>
>
> I have recalculated Rhodes crackle slip for bisque here in
>Mashiko, but it doesn't crackle. If I add some bentonite, would that
>help it shrink and crackle?
>
> I have always thought using this slip under a clear glaze is
>a good way to get the crackle look of a crazing glaze, but with a
>smooth surface.
>
>--
>Lee in Mashiko, Japan
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Bill Merrill on tue 8 jan 08
Slips are made for different temperatures. The ingredients are very
similar, the fluxes change. Slips can be made to be put on leather
hard, bisque and on a dry body. Daniel Rhodes has a section in his book
on slips and so does Val Cushing. One of the ingredients used to make
the slip harder in the dry stage is borax. I would use borax over
bentonite to make your slip harder when dry.
=20
Here is a slip that works on greenware, on bisqueware and if used thinly
it can be used on lather hard ware. This is a cone 10 slip called
Volkous slip. Pete did this slip 50 years ago. Dave Shaner used this
slip. If you want to decorate with it take the basic slip and add 75 %
iron to it. Use it thinner under a glaze or over a glaze. I use it over
a glaze to darken the area where I paint it. Dave would do a wax
decoration on green ware and use the iron slip over it. When the pot
was bisqued the wax burned off and than a glaze was applied over it.
This slip can also have cobalt added to it.
=20
25 Neph Sy
20 EPK
20 OM4
30 Flint
5 Borax
=20
You can see by the amount of plastic clays and othe non plastic
materials that this slip doesn't have an extreme shrinkage, that's why
it worked well on dry or bisqueware.
Try slip training it on leatherhard ware and dry it slowly. If I were
to alter it for trailing I would cut out some of the flint and add more
to the plastic clay content.
=20
=20
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of Ron Roy
Sent: Monday, January 07, 2008 10:29 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: More slip advice
=20
Sometimes adding bentonite will make a slip stronger - up to a point.
The
problem will be in controlling the shrinkage so it does not fall off.
=20
I have never done it but I would try ball clay first as it will be
easier
to control from batch to batch.
=20
I have some experience getting that effect spraying sugar water on
powdered
glaze on a horizontal surface - the more water the more "crazing"
happened.
You may be able to find one of my snow plates to see the effect - look
for
it on the digital fire web site.
=20
You may find spraying the slip after it's on the pot with something to
get
it to crack up.
=20
You can google Ron Roy but you have to wade through Ron Roy the
childrens
book author to find my pots.
=20
RR
=20
>On 1/7/08, Ron Roy wrote:
>> Most slips that are applied to green or bisque will need to be
>> deflocculated - especially if they are applied thickly.
>>=20
>=20
> I have recalculated Rhodes crackle slip for bisque here in
>Mashiko, but it doesn't crackle. If I add some bentonite, would that
>help it shrink and crackle?
>=20
> I have always thought using this slip under a clear glaze is
>a good way to get the crackle look of a crazing glaze, but with a
>smooth surface.
>=20
>--
>Lee in Mashiko, Japan
=20
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
=20
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=20
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