Craig Martell on sun 26 may 02
Hello Jennifer:
If you are using a commercial clay and want to get an accurate weight with
the added colorants, you can cut thin strips off a block of moist clay and
let it dry completely. After it's dry, mash it up well and weigh out what
you need and add the colorants. Add the dry clay to water. For example,
if you are going to do a 500 gram batch, which will make about one quart,
add 500ml of water to a container and then dump in the dry slip and
colorants. Let them slake and hydrate a bit and then mix and screen thru
an 80 mesh if you want the slip to be really smooth.
If you don't want to use the above method, just figure that the moist clay
holds about 25% water so 100 grams of moist clay will have about 75 grams
of dry ingredients. This will get you in the ball park for adding the
colorants and it's close. Method number one is very accurate.
regards, Craig Martell in Oregon
Jennifer Buckner on sun 26 may 02
I am scheduled to take a slip carving workshop in a week, and was told on
Friday that I am required to bring several still-damp, thrown and slipped
items. My problem is that, as a neophyte, I've never made slip before and
now I'm in a bit of a panic. I'm hoping someone can help me.
I looked up the material in Vince Pitelka's book, and checked the archives,
but it appears that the usual method involves making slip from the same dry
ingredients as one's clay, then adding colourants. At this point, I'm
using commercial porcelain and have no idea what it contains. My question
is: can I simply add water to my clay to make it more liquid and then add
a Mason stain (I have one black Mason stain at the moment) or an
oxide? How will I know how much colourant to add?
I'd appreciate any help.
Jennifer
Jennifer G. Buckner jenniverre@pgtv.net
Jeff Tsai on mon 27 may 02
Jennifer,
There are slip recipes that don't require using the same clay, but to get
the
best fit, using the same clay would help.
You can just add water to the clay and turn it into a slip. This might take
some time though. Try rolling the clay into real thin slabs and drying them
in the sun first. Then, when it is bone dry, crush the clay up into a
powdery
substance...it doesn't have to as fine as EPK out of a bag, just crushed up
some. Add water to this and blend with a jiffy mixer or by hand. You'lll
have
an easier time making the dried out crushed up clay into a slip than wet
stuff.
If you're using Mason stains to color, you could do the additions by volume.
I know in terra sigs (a sort of thinned out slip), I've read about using 2
teaspoons of mason stain for every cup of slip. Try that, should work fine,
might even be more color than you need.
IF you are making color using oxides...well, I don't know that there is as
simple a method. I'm sure a small addition, like a teaspoon of cobalt oxide
to a cup of slip, would give a pretty strong blue, and a couple teaspoons of
red iron oxide to a cup of slip would probably give a nice red/brown. but
this might also change how much the slip shrinks...
Anyway, it's just a workshop, and you go to workshops to learn, at least I
do. Most of the stuff I've ever made at workshops goes in the trash
eventually. Once I've come back from the workshop and have more time and the
new knowledge, I can do a better job anyway. So, don't worry so much, I'm
sure you'll find out from the other participants and the workshop leader
what
works best.
-jeff
Donna Sparks at Almost Art on mon 27 may 02
yes, you can just water down the commercial clay for slip, particularly if
you are applying it to the wet clay or leather hard. try different
thicknesses without any colorant. and then add 'some' of your one mason
stain.and then a batch with 'some' more. If all you have is black, you are
bound to get some greys.
SusanRaku@AOL.COM on mon 27 may 02
In a message dated 5/27/2002 3:27:12 PM Eastern Daylight Time,
snail@MINDSPRING.COM writes:
> I'd be inclined to add a little
>
What does the frit do?
Susan
Jim Kasper on mon 27 may 02
Hi Jennifer,
I am a long time neophyte ( I luv oxymorons too)
I too use commercial porcelain ( Axners: Mary's cone 6)
>can I simply add water to my clay to make it more liquid >and then add a
Mason stain?
Yes
>or an oxide?
Yes
How will I know how much colourant to add?
I originally went by what looked good.
In a pint of slip, a little thinner than corn syrup I add about 3 teaspoons
of slip. Some stains darken when fired to
cone 6 ( blues and blacks)
SOme fade ( reds, pinks)
Purple can lose all the red when fired high.
I have only used cobolt oxide and it does take less oxide than mason stain
to get the same blue, I used half a teaspoon and got a pretty reasonable
blue.
but as everyone says, ya gotta play :)
Regards,
Jim
Looking forward to years of of play.
Snail Scott on mon 27 may 02
At 08:15 PM 5/26/02 -0400, you wrote:
My question
>is: can I simply add water to my clay to make it more liquid and then add
>a Mason stain (I have one black Mason stain at the moment) or an
>oxide? How will I know how much colourant to add?
Yes! You may find that it's easier to dry your clay
first, though, and re-wet it to slip consistency.
Just smoosh out a lot of thin potato-chip shapes of
clay and set them in the sun or in the oven - they'll
be dry in no time. (Dry clay is always easier to
slake and moisten than clay that's already damp.)
I haven't added stains to porcelain for a while, but
I'd guess you'll need about 40% to get a really dense
black. (Another advantage of drying the clay first -
you can actually measure the dry weight of the material
for your percentage.) I'd be inclined to add a little
(10%) frit to offset the effect of all that stain, but
you may not have to. Do you have time to test your
combination before the workshop?
-Snail
David Hewitt on tue 28 may 02
I have always made my slips from the same clay as I use for throwing. I
save my turnings and let them dry and then crush to a powder and then
sieve with a coarse sieve.
You can see more details of my slips and the oxides and stains that I
use on my web site under Pottery Techniques / Making slip for
Decorating.
http://www.dhpot.demon.co.uk
David
In message , Jeff Tsai writes
>Jennifer,
>
>There are slip recipes that don't require using the same clay, but to get=
> the
>best fit, using the same clay would help.
>
>You can just add water to the clay and turn it into a slip. This might ta=
>ke
>some time though. Try rolling the clay into real thin slabs and drying th=
>em
>in the sun first. Then, when it is bone dry, crush the clay up into a pow=
>dery
>substance...it doesn't have to as fine as EPK out of a bag, just crushed =
>up
>some. Add water to this and blend with a jiffy mixer or by hand. You'lll =
>have
>an easier time making the dried out crushed up clay into a slip than wet
>stuff.
>
>If you're using Mason stains to color, you could do the additions by volu=
>me.
>I know in terra sigs (a sort of thinned out slip), I've read about using =
>2
>teaspoons of mason stain for every cup of slip. Try that, should work fin=
>e,
>might even be more color than you need.
>
>IF you are making color using oxides...well, I don't know that there is a=
>s
>simple a method. I'm sure a small addition, like a teaspoon of cobalt oxi=
>de
>to a cup of slip, would give a pretty strong blue, and a couple teaspoons=
> of
>red iron oxide to a cup of slip would probably give a nice red/brown. but
>this might also change how much the slip shrinks...
>
>Anyway, it's just a workshop, and you go to workshops to learn, at least =
>I
>do. Most of the stuff I've ever made at workshops goes in the trash
>eventually. Once I've come back from the workshop and have more time and =
>the
>new knowledge, I can do a better job anyway. So, don't worry so much, I'm
>sure you'll find out from the other participants and the workshop leader =
>what
>works best.
>
>-jeff
--
David Hewitt
David Hewitt Pottery ,
7 Fairfield Road, Caerleon, Newport,
South Wales, NP18 3DQ, UK. Tel:- +44 (0) 1633 420647
FAX:- +44 (0) 870 1617274
Web site http://www.dhpot.demon.co.uk
Snail Scott on tue 28 may 02
At 11:22 PM 5/27/02 EDT, you wrote:
>What does the frit do?
Since stains can be rather refractory, high
concentrations (30%-40%) can affect the look
of slips and engobes. So, if the test results
look a little dry, I'll add small amounts of
frit (5%-15%) to compensate. If the slip is
intended to be glazed, I wouldn't bother, but
for an exposed slip surface, it can make the
result more 'hand-friendly' and a bit smoother
in appearance.
-Snail
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