nancy patterson on sat 12 apr 03
Iwant to make some slips for brushing and trailing.
I am throwing with a med brown groggy cone 6 clay.
and just was given a bag of similar clay, but grooggy white 6.
I don't know how much colorants to add to the slip?
I have some stains given to me by a retired potter
and would like to use them or my oxide.
Where do I start?
Thanks so much for all the help I have learned so much reading through the
posts.
nancy
ncy@nyc.rr.com
Lily Krakowski on sat 12 apr 03
Where do you start?
For one generally one uses smooth, not grogged clay for slip decoration, and
one has to be sure that the slip will fit the body clay properly. As a rule
of thumb one uses about twice the amount of colorant in a slip than one
would in a glaze. On the one hand this makes the experiment costlier, on
the other the reclaimability of a pot that has been slipped leatherhard and
found wanting makes up for that.
What you need to do is make some tests, and preferably get one of the
excellent books on slip decoration. Your public library can get one for
you.
nancy patterson writes:
> Iwant to make some slips for brushing and trailing.
> I am throwing with a med brown groggy cone 6 clay.
> and just was given a bag of similar clay, but grooggy white 6.
> I don't know how much colorants to add to the slip?
> I have some stains given to me by a retired potter
> and would like to use them or my oxide.
> Where do I start?
> Thanks so much for all the help I have learned so much reading through the
> posts.
> nancy
> ncy@nyc.rr.com
>
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Lili Krakowski
P.O. Box #1
Constableville, N.Y.
(315) 942-5916/ 397-2389
Be of good courage....
Snail Scott on sat 12 apr 03
At 03:29 PM 4/12/03 -0400, you wrote:
>Iwant to make some slips for brushing and trailing...
>I don't know how much colorants to add to the slip?
Depends on the colors you want, and the oxides (or
stains) that you use.
A percent of cobalt carb will give light blue; 2-3%
for nice medium blues. Iron can be anywhere from 5%
for tan to 15% for deeper color. Chrome and copper
are mostly good in the 5%-10% range, but you will have
to test your own clay, and decide what you want. You
can add zircopax to whiten the slip, to help it cover
the red clay body better. Stains are weaker colorants,
so 10%-30% is more typical for those.
If it's really groggy clay, it may make a rough slip
unless sieved.
-Snail
Alisa Liskin Clausen on sun 13 apr 03
Snail's percentages are more or less what I use. For stains, I color by
sight these days, however, when I weigh out dry slip, it is usually between
15-20% stain. The only colorant that had given me trouble is Zircopax.
It is extremely refractory. It can cause crazing when a slip with additives
comes in-between the clay body and a glaze. I would recommend if you have
crazing with the white, that you blend in some frit to your slip with
Zircopax, to give it more flux.
It sounds like you received a bag of clay. Wet. The percentage of oxides
and colorants are suggested for dry mixture. You can wet down your clay,
make a slurry and sieve it, if groggy.
Next, you can dry it out and break it up. Weigh out 100 to 200 gm. batches
for coloring and testing. A lengthy process. When I color slips from the
clay left in my splash pan (great consistency for instant slips) I color by
sight. I go very light handed with cobalt because it is very strong and can
easily be oversaturated. For the pots I make, I do not need greatly
consistent colors.
good luck,
best regards from Alisa in Denmark
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