Ceramic Art Trends, Tools, and Techniques for Potters Worldwide


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Studio Maintenance

Caring for Your Kiln Shelves

Kiln shelves are expensive, so you need to take special care of them. After repeated use at high temperatures, you may notice that they begin to warp. But this can be prevented by some simple maintenance procedures.

If you use kiln wash (that is, a refractory material like alumina hydrate, or a mixture of silica and kaolin that has been mixed with water and applied with a brush) you restrict the way in which your shelves can be used. If you use exactly the same material but apply it dry by sieving it onto the shelf, it can be easily brushed off and the shelf turned over each firing. This helps to eliminate warping because if warping begins, it is counteracted in the next firing when the shelf is turned over.

Rotating the shelf is also a good practice. Try marking one edge of each shelf with a letter or number, and an arrow pointing upward. For the first firing the number/letter is at the front with the arrow pointing upward.

For the second firing, turn the number/arrow to the back of the kiln, with the arrow pointing up. For the third firing, brush the dry shelf coating off the shelf and turn it over so the number/letter is to the back of the kiln, but the arrow is pointed downward. For the fourth firing, rotate the shelf so the number/letter is to the front of the kiln, with the arrow pointing downward. Record this in your kiln firing log and keep to this sequence, and your shelves should last much longer.

Production Pottery Tips

The process of making large quantities of consistent-quality pots can be haphazard and frustrating when attempted without a plan. Yet a bit of organization in the studio, combined with a logical work schedule, can maximize both the quality and quantity of pots you produce.

  • Re-arrange your studio if necessary to reflect your work patterns, so you're not spending your time searching for tools or walking back and forth to get things that could have been placed within easy reach.
  • Try to set up a work schedule with efficiency in mind. Perhaps you can spend a few weeks doing all of your throwing or handbuilding, making pieces in the morning and trimming them in the evening. During following weeks, you could alternate between loading and unloading your bisque firing, preparing your glazes, and glazing. Then fire everything, and package or store your pots, pricing them if necessary. Throw in a day or two for bookkeeping, delivery of pots to retailers, or show travel, and the cycle begins again.
  • To yield consistent results when making sets of mugs, plates, etc., determine the amount of clay you need for each item, weigh it, and record that weight in a log book. Before you begin to throw, weigh out and wedge your clay, put on bats and cover with plastic wrap, then arrange on a shelf next to your wheel so that you can make piece after piece without leaving your seat. Keep a shrink rule and calipers within reach so that you can check and refine measurements of height and diameter.
  • Try to make at least a dozen or more of each piece at each sitting, as you'll become more efficient at making that item with every repetition. This holds true for both wheel-thrown and hand-built works.
  • When handbuilding, make your slabs, coils, etc. as large/long as possible, then measure and cut each part into the size you need. This will assure more consistent results (i.e., one slab cut into six parts to make a box will assure walls of an equal thickness.)
  • Perform each phase of the pottery-making process on as many pieces as possible at any given time. For example, if you apply blue and green slip to your pots, first apply the blue slip to all of the pots, then the green slip. This is very efficient when compared with painting both colors on each piece individually.
  • Be sure to take frequent breaks from the wheel or work table. Walk around outside or do some stretching exercises to relieve tension.
  • Allow yourself plenty of time to complete your work. If you wait until the last minute, you could not only suffer unnecessary stress and fatigue, but the quality of your work may suffer. Even worse, this can take the enjoyment out of potting - and who wants that?

Recipe to Purge Lead From Kilns

It's best not to use lead in the studio at all because it is dangerously toxic. Yet if you insist on using lead for decorative purposes, be aware that during firing, lead migrates not only to food-safe pieces in the kiln, but also to the kiln walls themselves. The lead is then re-released in subsequent firings, essentially contaminating any food-safe work that you fire in the same kiln. Therefore, lead-containing pots should ideally be fired in a separate kiln designated solely for decorative pieces.

Unfortunately, firing in separate kilns is not always practical. In such cases, you may wish to try the following recipe for "purging" the lead from your kiln between firings. Although not guaranteed as 100 percent effective, it can be used between lead firings, then home lead ceramic tests can be performed to assure that food-safe wares are lead-free.

To Purge: Obtain a kiln-safe container as close to the interior dimensions of the kiln as possible. (If necessary, make one of clay.) Fill the container with nepheline syenite, which attracts lead. Fire at a heat rise of 270 degrees F per hour until it reaches 2000 degrees F (around cone 04), holding the temperature constant for two hours. The nepheline syenite will draw the lead from the kiln walls, turn yellow, and appear to mold together. After firing, dispose of the nepheline syenite. To be sure subsequently fired wares are lead-free, check with a lead test kit available from your local pottery supplier.

Setting Up an Efficient Studio

Whether you already have your own pottery studio or you're just beginning to piece one together, there are some important considerations which can help your set-up serve you better.

First, try to select a spot with as much space as possible. Equipment such as wheels, slab rollers, and kilns can quickly consume a great deal of space, as can your inventory of glaze materials, five-gallon buckets of prepared glaze, shelving, and so forth.

Before moving any equipment into your studio space, consider painting the walls with a semi-gloss or wipe-clean variety of paint. You may also want to seal your floor to protect it from exposure to moisture and prevent it from absorbing clay dust or spilled glaze ingredients. This is important because the absorbed dust can build up over time, releasing free silica and other harmful ingredients into the air whenever there's activity in the room.

When deciding how to arrange your equipment, consider your work patterns. For example, your first step is probably reaching for the clay, then weighing or dividing it and wedging or milling it. Next, you probably take it to the wheel for throwing or to the slab roller or worktable for handbuilding. Afterward, you place it where it can dry slowly. Draw up a rough studio plan with these ideas in mind, trying to arrange your equipment so that it minimizes unnecessary interruption of the work flow. Before you put the plan on paper, be sure to record the dimensions of the studio space and measurements of each piece of equipment so you'll know just where to place it when moving it into the room.

As you decide where to locate your equipment, consider proximity to the closest available water supply and electrical outlets. Depending on the amount of space you have to work with and your studio set-up budget, you may wish to call in a plumber to have a sink installed. A floor drain is also ideal, so you can hose down, then mop or squeegee the floor during clean-up sessions. If you have enough room to locate an electric kiln in the studio, you'll probably need to call in an electrician to upgrade the wiring. Also, you'll need to consider a ventilation system for your kiln to reduce exposure to harmful fumes emitted during firing.

Are there any windows in your studio space? If so, you may wish to place your wheel close enough to gaze outside or enjoy a bit of fresh air when throwing, yet far enough away so the glass isn't constantly covered with mud. If the sun shines directly into the room, take notice and try to locate your shelves away from the direct sunlight so your pots don't crack from drying out too quickly.

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