| From the pages of Pottery Making Illustrated
Slip Trailing for Beginners by Judi Munn
Above: mugs decorated with simple lines and dots, Spectrum Ceramics Raised Accents, L & R Specialties, cone 6 deep red clay, fired to cone 6 in an electric kiln.
| Many potters know slip only as the “glue” used to attach handles and
spouts. But a simple clay and water mixture is a wonderful decorating
tool because it allows for tremendous personal expression. Although
slip can be applied by using all of the same techniques as a glaze, the
slip trailer and commercial applicators offer a lot of great
opportunities.
Some Basics: Slip trailing is the application of decoration to a clay surface with lines
of slip using a fine pointed dispenser. This differs from glaze
trailing in several ways:
• Slips are generally applied to leather-hard work, even though some can be applied to bone dry or even bisqueware.
• Most slips do not move, run or flatten out during the firing. What you see is what you get.
• The raised surface creates physical as well as visual texture.
• Since the color is mixed with clay, it stays in place when dry and doesn’t dust off when rubbed. When bisque fired, the slip becomes part of the pot and stays on even when scraped.
These characteristics create a decorating technique ideal for designs
requiring precision, such as commemorative plates. Planning ahead lets
you put slip to work for you and make the most of its qualities.
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If you’ve never worked with slip before, it takes some getting used to.
Here are five simple steps that will help you get started . . .
1. Select your materials and tools. 2. Become familiar with how a trailer works. 3. Develop an idea of what you want to create. 4. Practice on a slab.
5. Try it for real!
Getting Started
The tools and materials needed for slip trailing are simple and can be
purchased (see “Supply Room,” ) or even fabricated in the
studio. You can make an inexpensive slip by soaking dried scraps of
your clay body in water. Let it soak until it’s a slurry and stir.
Screen it to remove all the lumps and grog and store it in an airtight
container. For a simple trailer use a condiment dispenser available in
most large kitchen departments.
If your trailer is not filled, remove the tip, squeeze the bottle and
insert the top of the trailer in the slip container. Ease off the
pressure and allow the trailer to draw in the slip then replace the tip.
TIP: Working with slip simplifies glazing. For this article, I used a cone 6 clear for the white clay and a cone 6 white liner for the red clay.
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1. Experiment with the trailer on a slab or tile.
| 2. Before drawing finished designs on clay, sketch out ideas.
| 3. Use a pencil or food coloring to sketch out designs on your pot. | 4. Start with simple line patterns.
| 5. Use a sponge to erase mistakes. Make sure you don’t leave any trace of the slip. It will leave a smear or shadow on the fired piece.
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To use the trailer, grasp the bulb or sides of the bottle, shake the slip down toward the tip, tilt the trailer to one side and gently squeeze. You can drag the tip on the clay as long as you are moving it away from the open end, so the slip is trailing out behind the applicator as you create a line. If you move it the other way, the tip will dig into the clay and get clogged.
Before creating a design, practice using the trailer on a slab of leather-hard clay. Get a feel for how the slip comes out and what kinds of lines you can make with it (figure 1). Spend time playing with different hand motions. If you’re used to a brush, using the trailer will feel a bit awkward at first. It takes practice to squeeze with the right pressure and move your hand at a steady pace to get a smooth line. After a number of tries, you may decide that the applicator is too big or too small for your hand. If that’s the case, find one that’s comfortable to use.
Once you’re done experimenting, make a test tile with brushwork and trailing with each slip you’re working with. Make one tile for each glaze you want to try, plus an unglazed tile. If you have any pinks, lavenders or purples, make sure that the glaze is zinc-free or the color will shift. I test all slips on wet, leather-hard and dry clay to give me an idea of the moisture range they can tolerate, and a soft leather-hard clay worked for all the materials tested here. You need to experiment to see how your slip works with your clay.
Plan Your Work
Once you know the kind of lines and strokes you can make, the next step is to sketch out ideas and plan your work (figure 2). By working them out on paper first, you can experiment with several possibilities before you commit one to clay. This way you can pick the one you like best and plan how you will approach it.
Draw your design or image on your pot with a pencil, or paint it on using food coloring—both burn out in the firing. Drawing on leather-hard clay is not as easy as drawing on a dry pot, and it creates a dent that’s hard to remove if you change your design, so use this technique only if your slip will tolerate a dry pot (figure 3).
Start Trailing!
Keep your first designs very simple. Like anything, it takes practice to get a feel for slip trailing. Start with simple wiggles, lines, dots or geometric patterns (figure 4). Eventually, practice will gives you confidence to make a strong bold line, not one that’s jittery and tentative.
Once you get to know the trailer and how it works, move on to single
color line drawings—flowers or animals are good images to start with.
Keep your sponge handy for erasing mistakes and for cleaning the tip of
the trailer (figure 5). Try to make your lines spontaneous and not too
careful or overworked. Have several pieces ready to decorate and allow
ideas to develop as you work.
At the beginning, when you’re most
prone to making mistakes, use only one layer of slip at a time. If you
put a base color down, draw over it and make an error, erasing this top
layer with a sponge can remove your under layer as well. Save more
complicated, layered ideas for later.
The form and surface you
choose to work on affects the ease of decoration. Plates and
cylindrical vessels are easier to work with than the inside of a bowl.
Your hand is likely to hit the side of a bowl as you apply a design to
the interior and can make your hand stop with a jerk. When you make
your pieces, make sure that the surface is smooth and free of deep
finger lines. A bumpy surface is harder to decorate.
| Further Exploration
Using slip allows you to create layers of
physical and visual texture. The potter can paint a layer on the
surface, brush another color over that, carve into it and trail a line
on top of that. The result is a multidimensional effect and can be used
to create detailed designs with depth. There are many
directions to take, so see where the trail takes you! Your imagination
is the only limit. •
Judi Munn lives in Mountain View, Arkansas. She can be contacted at judimunn@yahoo.com.
Left: After practicing with a single color, move on to using several colors. Brush on a general form or background, then outline it and add details. Massing out the body of the subject can actually make it easier to draw. It gives you a form and space to start with. The down side is that it is harder to erase mistakes when working with layered slips. If you try this, let the bottom color set up for at least 30 minutes before you add the second. This way if you make a mistake with your trailing, the first color will stay in place when you try to erase it. |
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Trouble Shooting
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Clogged tip
| If the trailer gets clogged, insert a wire, broom straw or paper clip to unclog it. If it is still clogged, take the tip off and wash it out. Then poke the paper clip though from the inside to the outside. Keep trying until you can get air to pass through it.
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Water in the trailer
| Slip settles over time and the water comes to the top. Shake the trailer, then tap it down on a table to get the bubbles out before you use it.
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Spitting
| Trapped air causes spitting. To avoid it, start with a full trailer. Always tap it or shake it down to get all of the air worked to the top. Once the air is out of the trailer, keep a constant pressure on the bulb. If you relax your hand and air gets in, shake it or tap it down again.
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Slip is cracking or falling off
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Your pot is too dry. Spray the decoration lightly several times and the decoration will stick back down (figure at left). Be careful not to over-soak it all at once or the decoration will dissolve!
Test the slip(s) first on wet, leather hard and dry clay and see what works for you.
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Mistakes! | If you are using a leather-hard pot, errors are easy to correct with a sponge. Be sure to clean the area well. If the decoration on your piece is bone dry, it is harder to correct mistakes. The color can sink into the clay and create a residual shadow.
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Slip comes out of the trailer too quickly,
the line flattens out, runs or becomes too wide
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The slip is too thin. Add thicker slip if you have it. If not, try using a smaller tip on your trailer. Amaco has a very tiny tip and Spectrum has a metal tip that can be attached to the tip of a trailer to make a finer line. You can also leave the top off of the container and allow some of the water to evaporate (bottom line in figure at left).
| Slip is hard to squeeze out and creates
sharp points | The slip is too thick. Add more water and mix it up. Slip should be like thick cream (top line in figure above)!
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The slip is gooey
| Some commercial slips have anti-settling additives that make them gummy. When you pull the trailer away, the slip adheres to itself and does not separate, creating a stringy line between marks. Be very precise when you stop squeezing and pull the trailer away. If this does not work, thin the slip with water and use a narrower tip on your trailer.
| The color changed when I glazed it
| Use a zinc free clear glaze. Some colors, such as pinks and lavenders, are affected by the presence of zinc in the glaze.
| Uneven surface of a pot is hard to decorate on
| When you make your pot, rib the surface smooth. If you still have deep finger ridges, trim it smooth when it is leather hard.
| The final product is pitted
| Some slips will go higher than cone 6, others will not. The black is especially prone to pitting at higher temperatures. All colors will take higher temperatures without glaze on them.
| A bisqued smudge
| Sandpaper or soft brick can be used to sand off a stray smear. If it is a heavy line, it is best to leave it. These are very hard to remove and will leave a shadow.
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