When many potters or ceramic artists think of slip, they think of it as the “glue” that is used to attach one piece of clay to another. But slip is one of those ceramic items that has many different functions – from slipping and scoring, to slip casting forms to decorating, slip is an essential tool for the pottery studio.
Today, potter Judi Munn gives us a primer on slip trailing, one of the ways potters and ceramic artists can use slip as a decorative element in their work. Follow these simple guidelines to create lovely slip-trailed decoration on your own work. – Jennifer Harnetty, editor.
The Beauty of Slip
This 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 of Slip Trailing
Slip trailing is the application to a clay surface of lines of slip using a fine-pointed dispenser. It 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.
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:
- Select your materials and tools.
- Become familiar with how a trailer works.
- Develop an idea of what you want to create.
Practice on a slab.
- Try it for real!
The tools and materials needed for slip trailing are simple and can be purchased 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.
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. 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.
Judi Munn is a potter living in Mountain View, Arkansas.