Richard C. Aerni on fri 22 mar 96
Hello everyone,
I'm back at work in the studio after spending two days at NCECA. This was
my first real exposure to one of these conferences, and it was pretty
exciting. Between seeing all the various exhibitions, catching the demos,
the slides and various lectures, not to mention the socializing, it was a
real whirl. The Clayart breakfast was well attended, with about 40 of us
there. It was nice to put faces to names, and we spent a lively hour and a
half together.
I've got a question to put to the group. This is something I've been trying
to do for years, without success, and I was wondering if anyone out there
would have any bright ideas that might help me out. I single fire my work
to cone 10, and use a lot of slips and slip trailing on the pieces. I've
been trying to find a way to get a lot of slip on the piece so as to soften
the profile, to add texture, and just in general to have fun gooping and
gobbing the stuff on. (plates and bowls) I've tried many different slip
recipes over the years; I've worked with them very thick and stiff; I've
deflocculated them so as to have less water in the mix; I've calcined the
clays that went into them; I've used slurry from the clay body the pot was
made of; I've put the slips on just after the pot was thrown, when
leatherhard, and when bone dry--none of these things seem to help. The slip
wants to peel back off the clay, or have cracks running through it as it
dries, or if not then, they appear during the firing. Does anyone have any
ideas how I could go about getting the slip on thickly without the cracking
and peeling?
I've included a several slip recipes I have used/am using, to give a general
idea of my approaches:
Slip #1
EPK (kaolin) 30.8
Ball Clay 12.0
Goldart Clay 18.8
K Spar 18.8
Silica 15.4
Borax 4.2
______
100.0
Slip #2
K Spar 34.0
EPK(Kaolin) 34.0
Silica 22.0
Whiting 4.0
Tin Oxide 4.0
Borax 2.0
_____
100.0
Slip #3
Ball Clay 75.0
Kaolin 10.0
Silica 10.0
K Spar 5.0
Ash 3.0
_____
103.0
Thanks for any help you may be able to give.
Richard
2975 County Road 40
Bloomfield, NY 14469
Phone (716) 657-6045
Fax (716) 657-6023 call before faxing
email rcaerni@cyber1.servtech.com
"...if it don't kill me, I'll be a better man for it..."
Dave Eitel on sat 23 mar 96
>I've got a question to put to the group. This is something I've been trying
>to do for years, without success, and I was wondering if anyone out there
>would have any bright ideas that might help me out. I single fire my work
>to cone 10, and use a lot of slips and slip trailing on the pieces. I've
>been trying to find a way to get a lot of slip on the piece so as to soften
>the profile, to add texture, and just in general to have fun gooping and
>gobbing the stuff on.
I have such limited experience with slip I shouldn't even answer, but I've
always used real slip--i.e. from throwing--with which to decorate.
Obviously it's a perfect fit, and I've never had problems. Maybe the
problem is more with when you put it on, that is at what stage of dryness.
The wetter the better, I suppose. Are your problems occuring when the pots
dry, or after you glaze them? I don't have experience with single firing.
Dave...waiting patiently for over-the-counter rogaine
Dave Eitel
Cedar Creek Pottery
Cedarburg, WI
daveitel@execpc.com
Donald P. Chitwood/Jane Peterson on sat 23 mar 96
>----------------------------Original message----------------------------
Hi Richard,
At the John Glick workshop here in Portland recently, John added a few
drops of a saturated solution of epsom salts to his slip, and it thickened
right up. Don't know if that will work for you, but you might try it.
Also, I remember a few years back that Chris Staley was using very thick
slip spread in graceful swirls all over his large pots. I believe there
was an article in Ceramics Monthly about that time - say three to five
years ago. I forget his formula. I think he started with the same base as
his clay, then deflocculated it, but I could be wrong. Perhaps someone
else knows about this?
Good luck.
Jane Peterson
Laughing Bones Art Studio
bones@teleport.com
Don Jones on sat 23 mar 96
> Does anyone have any
>ideas how I could go about getting the slip on thickly without the cracking
>and peeling?
Try spraying it on in layers. there was an article in CM about a woman who
sprayed on thick glazes with an interesting effect.
Don Jones
Richard Burkett on sun 24 mar 96
Richard,
I've done this from time to time on my work. Slip composition and timing of
application seem to be the critical factors. I'd eliminate the borax and if
anything slightly deflocculate your slip. Any average porcelain body (usually
half plastic clay) will probably work for white slip. The person who posted
about Chris Staley was right, he uses the same clay as his clay body, just
slightly deflocculated which may be the easiest solution. Having a slip that
contains a range of clay particle sizes will help (ie. a mix of kaolin and
ball clay), and a bit of bentonite may even help dry strength and adhesion.
Picking the right point to apply the slip is critical. Slightly softer than
leather hard would be my guess for a starting point for most bodies. Too soft
and you'll risk splitting from excess moisture, too dry and you'll get
splitting from rewetting, but you probably already know this. Any scumming of
the surface before you apply slip may keep the slip from adhering properly,
too. Lightly scraping the surface before applying may help here if you don't
like using barium carbonate in your clay.
Mix the slip VERY thick, sort of a gel consistency rather than brushable
liquid if you want to apply it thickly, so you can scoop handfuls of it out
to apply it. An easy way to do this is to put the dry materials in a bucket
(or dry pieces of your clay body) CAREFULLY cover with water (and
deflocculent if needed) and let it sit overnight and slake. DO NOT STIR! In
the morning carefully pour off all excess water and blunge. The slip should
be close to an ideal consistency, but may still be slightly too soft for
really thick applications.
If the slip is deflocculated too much it may lack the viscosity to hold it's
shape, and tend to flow. Adding a bit of acid (vinegar is fine) will
conteract the deflocculation and thicken deflocculated slip quickly.
Hope this helps. no real easy answer, as it will depend a lot on your working
methods and clay body. And you've probably heard all this before...
Richard Burkett -
School of Art, Design, & Art History, SDSU, San Diego, CA 92182
E-mail: richard.burkett@sdsu.edu <-> Voice mail: (619) 594-6201
LBlos72758@aol.com on sun 24 mar 96
Hi Richard,
Wasn't it fun meeting and seeing everyone?? Carol and I had a great time -
she is so much fun - everyone she meets is an instant friend. I went
through this thick slip thing too. The best I could do was add fine grog to
it and add it when the clay was wet. I even tried scoring the clay, making
the slip with very little water, etc. Only adding the grog made a
difference, but it was grainy. Maybe we want too much?! I guess if you use
the same clay as your body, have the clay really soft, and the slip as stiff
as possible - well, I'll try some more and see how it goes.
It was snow and ice all the way from Rochester.
Linda
Ithaca, NY
Bill Buckner on mon 25 mar 96
I have been using thick slips in my recent work. Originally, I used a
thick version of a decorative slip. But, I soon found that using a slipped
version of my porcelain body worked much more satisfactorily. The body is
a bit thixotropic. So, in the jug it is almost solid. A quick shake
liquifies it. It then gels fairly quickly after application. I apply the
slip as soon as I am finished throwing by either spooning it on or
squirting it from a flexible bottle and spout, then I move it with a wide
brush. It goes on my stoneware body without cracking or adhesion problems
(there are ocassional superficial hairline cracks, which the glaze readily
fills in). Because of the way I want it to move on the clay surface, I
have not tried applying the slip at later stages as the body clay is drying.
-Bill
Bill Buckner e-mail: bbuckner@gsu.edu
Georgia State University http://www.gsu.edu/~couwbb
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