Plaster work can be messy. Even though clay and plaster molds are frequently used together, the plaster and clay must never be mixed. All the clay used for making this mold can never be used for making fired pottery. It can be used for making another mold, however. In fact, use it for the second piece of this mold. But when you are finished, throw it away! Clay isn't that expensive. Better to throw away a little bit of clay rather than have a piece of pottery ruined because of plaster contamination.

Before you start weighing and mixing the plaster, cover your work surface with newspaper, and have a plastic-lined box or a plastic-lined trash can handy to discard excess plaster and plaster-soaked paper towels.

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You will need:

1 pound, 13 ounces of Plaster of Paris

1 pint (16 ounces) cold water

I doubled these amounts because of the size of my form (7 1/2 inches long) If your model is much smaller, you won't need as much plaster.

First, measure and pour the water into one of the mixing bowls. Set aside.

Next, set the second mixing bowl on the scale then adjust the scale to "0." This way, the scale will only register the weight of the plaster.

Scoop the needed amount of plaster in to the bowl. Wear the dust mask while doing this.

Sprinkle the plaster into the water. Do this as fast as you can, but don't drop it in by handfuls.The plaster particles need to be able to be wet thoroughly. Let it sit for about a minute, so the plaster is completely wet.

Insert your hand into the bowl, and carefully wiggle your fingers to mix the plaster. Take care to not stir vigorously, as this will cause air bubbles. Mix until the plaster is the consistency of heavy cream.

Pour mixture over your model. Pour as low inside the box as you can; this minimizes splashing and air bubbles.

Check the depth of the plaster by carefully sticking your finger in to touch the highest point of your model. There should be at least an inch of plaster covering it. If the layer of plaster is too thin, you may mix more plaster and pour another layer. This works best if done immediately.

While waiting for the plaster mold to set is the time to clean up the mixing bowl before the plaster residue can set up in it. Do not rinse and pour plaster or plaster water down the sink! The plaster would set in the pipes and block them.

Instead, quickly wipe out the bowl with paper towels, getting most of the plaster. With wet paper towels, wipe out plaster smears.

Immerse the bowl into the water-filled bucket to remove any remaining plaster particles. The water will be faintly cloudy. Allow the plaster to settle out. Pour off the water into your garden, and discard the settled out plaster in the trash.

Once the mold is set and removed from the "box," clean the vinyl "wall" and "floor" by scraping off any moist lay adhering to them with the fettling knife. Wipe with a damp paper towel. There may be a few bits of hardened plaster which are easily removed.

It will be about an hour before the plaster is hard enough to handle. During the setting-up process, the plaster will become quite warm. Once this stage is over, you can remove the mold walls and floor. You might have to pry the clay model away from the plaster mold using the fettling knife. Be careful not to gouge the inner surface of the mold. Remove the clay coils from the edge of the mold. Now, use the fettling knife to scrape away and round any sharp edges that could break off during use.

Use a damp sponge to wipe off any remaining clay.

Set your mold in a warm place to dry. Do not dry in your oven. High temperatures will ruin a plaster mold.

Repeat instructions starting on page four for the second part of the mold.

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