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Once you find a clay deposit you can test it to see if it can be used for throwing by picking up a handful of moist dirt and squeeze it in the palm of your hand.
If it crumbles it is probably not plastic enough for throwing.
If it seems to hold together it is a good bet that it will work for you, so go ahead and dig a bucket full and take it home.

When you dig your own clay there is bound to be debris such as stones, roots and grit.
In order to clean it, spread it out on wooden boards and let it dry in the sun.
As soon as it dries use a wooden mallet or block to break it up.
Now you are ready to mix the clay with water.
Use twice as much water as you have clay.
Let it settle for a few hours.
Strain it through a 40 mesh sieve.
Let it settle for a few more hours and then pour off the excess water from the top.
It is now the consistency of thick slip so pour it out onto a big plaster of paris block so it can dry to a working consistency and then it will be ready to wedge.
The plaster of paris draws the moisture out of the clay very rapidly.
That is why ceramic molds are made from plaster of paris.

Try testing it by throwing a few pieces on the wheel and cut some test strips. Measure and fire them at different temperatures and keep track of the characteristics, then measure again to check for shrinkage.
Keep track of the workability of the clay, the fired color, its porosity and the highest firing temperature before slumping.
To check for slumping take a dried test strip and put it across two previously fired test tiles that are stood on edge.
Once you have found the maximum firing temperature, try a glaze firing in that range to check glaze fit.

Test various clays until you have found at least two with the qualities you want.
Each clay varies in particle size, the smaller particles of one type of clay will fill in the gaps where larger particles bond together.
This mixture of clays can then be used as 50 to 80 percent of the ingredients to make your final mixture, or clay body.
Other ingredients should include 10 percent silica and up to 20 percent each of a feldspar and a filler.

To mix the clay body, again spread out your strained, raw clay on plaster of paris block and let it dry out completely, then pulverize with a mallet to a fine powder.
Weigh out and mix the dry clay ingredients with proportions of silica, feldspar, and filler.
Grog is an excellent filler because it reduces shrinkage, provides throwing strength, and minimizes warping and cracking.
You can make your own grog by pulverizing some dried clay, then firing it to maturity in an unglazed, fired dish.
The fired particles may be crushed again to the point where they will pass through a 30-mesh screen, yet rest on an 80-mesh screen.
Add up to 10% grog to the dry clay body ingredients, mixing thoroughly.

Add water to the clay mix and blend into a thick smooth slip.
Again, dry on plaster of paris block until it can be handled and wedge until you feel that you have all the air out of the clay and store in tightly covered plastic bags in a cool, dark place.
Allow to age as long as possible.

Your clay may need to be modified.
If your clay body is too porous, add more feldspar.
If it shrinks too much, add grog.
Plasticity can be increased by adding 1 to 2% bentonite.
If the clay body is too plastic, more filler can be added.
To increase either density or porosity, try adding 5% to 20% more silica.

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Have you ever come up with a good idea while working with your pottery or ceramics and thought that you would like to share it with others? You have? Well, why not send it to us and we will add it to the tips page for all to see.

There are signs that pottery and ceramics are losing appeal for a younger generation. There are pottery and ceramic departments closing in teaching institutions throughout the country. The common understanding is that younger students are reluctant to commit themselves to the intensive study required to master pottery and ceramics. Why spend three years to learn just one art form when you can pick up PhotoShop in less than a week? Pottery wheels lie idle as students flock to the computer labs. With all the stressful actions in the world today, releasing that stress through pottery and ceramics would be very beneficial to ones well being.