Sandra Leinweber on wed 16 apr 97
hi, i am a ceramic student and my instructor recently mixed a batch of
slip for us to pour into plaster molds--relatively flat molds--some
relief. the slip is (for want of a better word) gummy, not very runny,
and does not seem to release its water readily into the plaster. we
used ball clay, water, and sodium silicate. we are thinking we got some
proportions wrong, or perhaps need other ingredients. we are looking
for a new recipe. can anyone help us. TIA sandra leinweber.
Marcia Selsor on thu 17 apr 97
Sandra Leinweber wrote:
>Kenny's book gives good instructions on slip preparation.
I have followed them with success. Especially the part where you must
mix (I used a jiffy mixer) several times/day for a week or so.
Maybe you should mix it with a mixer before using.
Marcia in Montana
>. the slip is (for want of a better word) gummy, not very runny,
> and does not seem to release its water readily into the plaster. we
> used ball clay, water, and sodium silicate. we are thinking we got some
Carly Gibran on fri 9 jun 06
I am a novice at slip making, but need some for a simple drop out mould. I have saved scraps of the
porcelain I use for throwing and hand building, and wanted to know if I soaked these dried scraps, is
there anything else I need to add to it so it will work in my plaster mould?
Ben Shelton on sat 10 jun 06
You will need to add deflocculant.
Many here will be more versed than I am at how to calculate proper amounts
but the basic problem is that if you make slip the way you describe it will
contain too much water to work well.
Clay has the wonderful property of flucculating. The particles of clay clump
together in the water making the resulting slip seem thicker than an
equivalent mix of a non-flocculating material such as gound silica. If you
mix 1/4 cup of silica with 1 cup of water and do the same with ball clay,
the clay mixture will seem much much thicker.
In order to break up the clumps of clay particles you use a deffloculant. (SP?)
There are a lto of books out there that will advise you better. I have one
called "The craft and art of clay" by Susan Peterson and I turn to it often.
On Page 92 She says that casting slip should contain no more water than 40%
of the dry weight of the other ingredients and .002~.005% defflocculant such
as soda ash, sodium silicate, or Darvon #7.
Let us know how it works out.
John Rodgers on sat 10 jun 06
Go to this web site, then scroll down the table of contents to "The Art
of Slipmaking" and select it. You will get a PDF file that will give you
complete instructions and discussion on slip making.
Best of luck,
Carly Gibran wrote:
> I am a novice at slip making, but need some for a simple drop out mould. I have saved scraps of the
> porcelain I use for throwing and hand building, and wanted to know if I soaked these dried scraps, is
> there anything else I need to add to it so it will work in my plaster mould?
> Carly Gibran
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Snail Scott on tue 13 jun 06
At 08:16 PM 6/13/2006 -0400, you wrote:
>...can suggest a specific source.
After reading the slip making threads, I think I'll go that
>way but I don't know where to get the supplies...
There are many clay suppliers in many places which
sell materials. If you tell us what area you live in,
someone can suggest a specific supplier nearby.
We have soda ash to use
>with our swimming pool. Will that do?
>Also, I don't want to make more than about 5 gallons. Do you know where I
>can find a recipe proportional to that amount.
Nearly all ceramics recipes are written as
percentages, so you can make any amount.
Just multiply each material by however much
you need. For 5 gallons, if you measure in
grams, just add two zeros to each number to
get a 10,000 gram batch: it will fill a 5
gallon bucket just about right. Or do half
that much, by multiplying by 50 instead of
If you buy just a pound of so of each of the
likely materials, you can do many tests at
low cost before committing to one recipe in
quantity. A 100 gram test batch will fit neatly
in a small tupperware-type container. Do tests
before you make 5 gallons of anything!
The archives of this list have quite a lot of
recipes, and you can go through potters.org for
a more organized arrangement of the same info.
There are also lots of recipes in books.
Karen Hamilton on tue 13 jun 06
I dug up some clay at an excavation site and would like to use it in some
application. After reading the slip making threads, I think I'll go that
way but I don't know where to get the supplies. We have soda ash to use
with our swimming pool. Will that do? And what about the other items?
Also, I don't want to make more than about 5 gallons. Do you know where I
can find a recipe proportional to that amount. Thanks.
Bob Masta on wed 14 jun 06
Before you get into slip making, you may want to
do some simple tests on this clay, to find out its
firing range. The native clay in my garden, for example,
is low-fire; it can be fired up to about cone 1 or 2
as a clay body.
At cone 6, however, it is completely melted and makes
a wonderful brown "Albany slip" glaze all by itself.
It has become one of my favorite glazes, and is
pretty much the only brown I use any more.
Another thing to watch out for is lime inclusions.
My clay has specks that cause "lime pops" when
used as a body, so must be sieved carefully to get
those little buggers out. (I use 100 mesh, which may
be finer than needed.)
A final reason to use this as glaze instead of body
is that it lasts a *lot* longer, for all the effort that
goes into digging, drying, screening out stones and sticks,
mixing, and sieving.
Just my 2 cents worth!
> Date: Tue, 13 Jun 2006 20:16:08 -0400
> From: Karen Hamilton
> Subject: Re: Making Slip
> I dug up some clay at an excavation site and would like to
> use it in some
> application. After reading the slip making threads, I think
> I'll go that
> way but I don't know where to get the supplies. We have
> soda ash to use
> with our swimming pool. Will that do? And what about the
> other items?
> Also, I don't want to make more than about 5 gallons. Do
> you know where I
> can find a recipe proportional to that amount. Thanks.
Karen Hamilton on thu 15 jun 06
I live in the Houston area. Found the sodium silicate this morning. Now,
if I could just find the recipe for slip that I forgot to bookmark.....