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general purpose slips

updated wed 28 jun 00


Alisa and Claus Clausen on sun 25 jun 00

I have several receipes for decorative slips.
Some are listed for wet to leatherhard
others are listed for bone dry or bisque
others are for all stages

What ingredients determine a slips attributes for wet, or dry or bisque?

I have the following receipes
Kaolin 5 parts
Ball clay 5
Cust. Feldspar 4
Silica 4

for leatherhard or bisque
Kaolin 4 parts
Ball clay 4
Cust. Feld. 5
Silica 6

Comparing the two above, it seems that the slips for wet have more clay
the slips for dry to bisque have more flux/hardener

Looking at Robin Hoppers receipe
Ball Clay 750
Kaolin 100
Flint 100
Feldspar 50

The ratio of Clay is very high to the flux/hardener. Would this mean it =
is meant for wet clay?

Cynthia Bringles slip is for wet, dry or bisque
Ball clay 800
Kaolin 800
Flint 1200
Neph. Sye 1000
Borax 200
Bentonite 80

Looking at the first 4 ingrediens identical to the first three receipes,
it seems that this slip would be more suited to dry to bisque (if I am =
even close in understanding)
How big a part (if any) does the borax have in expanding this slip's =
to adhere to any degree of wet to dry or bisqued surface? I am thinking =
it is added as flux. =20
But it is a small amount in comparison the rest of the ingredients. =
Could the felpspars be increased
and the borax dropped?
There is nothing on my list of raw materials called Borax or Boron.

I am in effect looking for a general slip to color that will be not =
shiver off under glazes.
Of course I test everything, but I am wondering if there is a general =
balance of material groups
I should begin working with such as=20
X amount Clay
X amount Flux-silica
to acheive a slip that can be applied from wet to bone dry.

Best regards,

Craig Martell on mon 26 jun 00

Alisa said:
>I have several receipes for decorative slips.
>Some are listed for wet to leatherhard
>others are listed for bone dry or bisque
>others are for all stages
>What ingredients determine a slips attributes for wet, or dry or bisque?


Slips that are high in clay and have a high wet to dry shrinkage are
usually meant for application to raw, unfired pots. There are many recipes
that are lower in the plastics and higher in non plastics like spar and
silica that are meant for application to bone dry and bisque pots.

I do mostly all slip decorating. I spray, paint, pour, and trail. I use a
cone 10 porcelain that I mix here at the studio. My slip base is the exact
same recipe as the porcelain throwing body. This eliminates any
compatibility problems and I don't want to change this recipe to compensate
for dryer or bisque applications. So, for bone dry and bisque application
I calcine some of the slip and use about a 50/50 raw to calcined blend of
the same recipe and everything works just fine. No slip or glaze fit
problems to worry about. Oh, I "dead burn", or calcine the slip to cone
06. It doesn't sinter at that temp and it's very easy to mix and screen if
I need to do that. I have some large bisqued crucible type bowls that I
use over and over in the calcine fire.

later, Craig Martell in Oregon

Wade Blocker on mon 26 jun 00

You are asking for the impossible.Slips for wet clay application must be
made to shrink with the body. Slips for dry or bisque ware have to have low
shrinkage, otherwise you get peeling or cracking. I have a recipe from
Conrad's book for an engobe for dry greenware or bisque that I use. If you
would like the recipe let me know.
Borax is a flux, easily available. Mia in ABQ