| From the pages of Pottery Making Illustrated
Supply Room: On The Trail by Judi Munn
Above: As you get into slip trailing, you’ll find your collection will grow. When I decorate, I have a number of slips lined up in trailers and small containers.
| Slip trailing is a time-honored decorating technique that’s very simple to get into. And while you can easily make your own slip and improvise a trailer (see this month's feature on Slip Trailing), ceramic manufacturers and suppliers provide a line of products specifically for this type of surface treatment.
Trailers
There are many ready-made slip trailers on the market. I use a red bulb
with a metal tip that I got from Highwater Clay. A large paper clip
fits in the tip to keep the slip from drying out or clogging the tip
when not in use. For a finer line, Amaco makes a small trailer with a
narrower gauge metal tip that works well. Axner also carries a small
trailer with interchangeable tips for various line widths. I use the
wire from a twist tie to keep the smaller tips clean.
You can also experiment with glue bottles, ketchup/mustard bottles,
hair dye applicators, nasal aspirators, ear syringes or any found
container with a small tip. Whatever you use, make sure it’s
comfortable to hold in your hand, that the tip can be removed, and that
you can make it airtight with a cap, plug or wire.
Some suppliers, such as Spectrum Ceramics and Minnesota Clay (among
others), sell pre-filled applicators, which can be refilled. This
all-in-one solution is a good way to get started. |
Slips
Many potters use the terms “slip” and “engobe” interchangeably. Slip is
generally considered to be clay thinned with water. Engobes look and
behave like a slip, but they have more glaze ingredients in them and
are more vitrified, or glass like. If you are searching on the web for
information about slip products to use, try both terms.
As mentioned above, some applicators are pre-filled. If you choose to
purchase applicators and slips separately, slips are available in both
liquid and dry form, although some suppliers may not carry both types.
If starting from powdered slip, add water to the container and allow
the materials to slake or become saturated overnight, then stir well.
It should not need to be screened before use.
The texture of these slips is very creamy, which makes them flow
easily. The wide selection of colors available let you be creative
without having to figure out the technical side of developing a color.
When decorating, keep a number of slips lined up in trailers and small
containers so you can switch between different colors easily as you
work.
After you have your slips, make test tiles so you will have an idea of
how they perform. Test them on wet, leather-hard and dry clay as well
as on bisqueware. Check for cracking and adhesion problems. After
bisque firing, apply a clear glaze and/or a white glaze over part of
the test and check for color changes and pitting after firing. Some
slips go higher than cone 6 and others do not. Black slip, because of
the high concentrations of colorants, tends to pit at higher
temperatures. Always test new slips before using them on finished
pieces.
Glazing
One benefit of working with slip is that it simplifies the glazing
process. You can use one glaze and still get a variety of colors by
using different slips. At cone 6, I’ve gotten good results by using a
clear glaze over slips on a white clay body. When glazing pots made
with a red clay body, I use a white liner glaze.
Naragon White Glaze
Cone 6
|
|
Gerstley Borate
| 26.0% |
Dolomite
| 3.0 |
Whiting
|
6.0 |
Kona F-4 Feldspar
| 32.0 |
Kaolin
|
8.0 |
Silica
| 25.0 |
| 100.0% | |
Add: |
| Zircopax
| 12.0% | Bentonite
| 2.0 |
|
|
Zinc-Free Clear Glaze
Cone 6
|
|
Gerstley Borate
| 35.0% |
Kona F-4 Feldspar
| 40.0 |
Ball Clay
| 15.0 |
Silica
| 10.0 |
| 100.0% |
Add:
|
| Bentonite
|
2.0% |
| Test the slips on unglazed clay and with a zinc free clear.
Top: Minnesota Clay Co. slips. Bottom left: Amaco engobes. Bottom right: Spectrum Glaze Raised Accents.
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| To prevent a clogged tip . . .
1. When creating your line, always move the applicator away from the open end of the tip. If you move in the other direction, it will dig into the surface of your pot and push clay into the tip.
2. If you store slip in an open container, before using, stir it with a wire whisk or inexpensive paintbrush until it is smooth and lump free.
3. To make the trailer air tight, use a cap or insert a paper clip or wire in the tip to prevent the slip from drying out.
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