View Larger Image Tips and techniques in our weekly series "Great Ideas for Potters" come from all levels of experience: studio artists, production potters, students, teachers and industry experts.

October 5, 2007

Tip of the Week: Tap Away Cracks in Pottery

by Ceramic Arts Daily | Read Comments (0)

Each week, we provide you with a selection of helpful hints and ideas drawn from suggestions submitted by Ceramic Arts Daily subscribers and Ceramics Monthly readers. You'll find great ideas for:

Forming processes
Decorating, glazing and firing
Outfitting your studio
Creating and using tools

Tip of the Week, Submitted by Merrily Edgecombe
Another way to ensure that the bottoms of your wheel-thrown items don't crack is to tap the center of the underside of the item that's still in the leatherhard stage with your finger. I have found that the ever so slight indentation your finger makes is enough to eliminate the S-shaped crack that appears in the drying state or when fired. This technique also works on hand-built flat bottom items. Thanks Merrily!

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Forming Processes

Reach for the petroleum jelly jar, not only to soothe those sandpapery fingers, but also to slow down drying. A thick coating can be applied to the edges of any ceramic form you want to dry slowly. Petroleum jelly is inexpensive, and a fingertip is a much more accurate applicator than a sponge or a brush full of wax resist. Also, smearing a hump mold with petroleum jelly will prevent stress cracks at the ware's edges, and will allow the form to slide off the mold easily. Cover a bat with G-inch-thick foam rubber to prevent hairline cracks from forming on the rims of pots when trimming. This is especially good for bowls with thin, flared rims that dry too quickly. The foam may be tacked underneath the bat or attached to the entire surface with white glue. The bonus is that bowls and low pots can be trimmed without the use of clay wads when placed on this padded bat. Draw concentric circles on the foam with waterproof markers to facilitate centering for trimming.

Decorating, Glazing and Firing

To check for shelf clearance when stacking a top-loading kiln, lay a transparent plastic drafting triangle across the posts. It is easy to see through the triangle to the pots below. A 14x10x10-inch triangle in an easy-to-find neon pink works perfectly in an 18-inch-diameter electric kiln. Bigger triangles are available for bigger kilns. When running low on glaze, it is still possible to dip-glaze large pieces by making a form-fitting basin from a shallow box lined with a heavy-duty trash bag. This technique also allows you to make appropriately sized containers for odd-shaped pieces.

Outfitting Your Studio

If you have a utility sink with pipe threading on the end of the faucet, it is possible to add a sprayer hose and nozzle at little cost. Simply purchase a garden hose "Y" fitting at your local garden center, then attach it to the end of the faucet. Next, screw a washing-machine hose onto one end of the "Y" fitting. Then, screw a trigger-type nozzle onto the end of the hose. The shut-off valves on the "Y" fitting will allow the faucet to be used as either a sprayer or a conventional tap. Buffet heating trays (purchased from secondhand stores) are useful for drying plaster molds or for cooling down pots when unloading a warm kiln.

Creating and Using Tools

No matter how many needle tools you have on hand while throwing, finding one when you need it never seems easy. By gluing a stiff foam block to the side of the wheel and sticking all your needle tools in it, you can keep them safely out of the way but readily available. Tiles purchased from a home-improvement center can be used as bats for small items thrown on a potter's wheel. Roll out a slab of clay, place it over the wheel head, then press a tile into it. When you are finished throwing an item, simply lift the tile and insert a new one.