It gets very easy relying on clay, fresh out of the box, be it terra cotta, stoneware or porcelain. In the case of my terra cotta, I have it made for me by the clay professionals at Standard Ceramics in Pittsburgh. Over the years I have made my fair share of clay including up to 600 pounds a day while I was the tech assistant at Cleveland State. Since then, though most of my clay is prepared clays, I have continued to make up small batches of varying clays for a variety of uses and specific needs. The process I use is quite simple; I measure out the ingredients in a 5 gallon bucket, mix it thoroughly into a slurry consistency, pour it out on plaster to firm up and finish up the process by vigorous wedging. All in all, not a terribly difficult undertaking as long as I keep it under 25 pounds or so.
Last summer I made up a clay body that I wanted to fire slightly darker than the normal stoneware I work with for use with a new Oribe glaze I was testing. The darker body with more iron, tempers the green and makes for a richer looking surface. I fired several bowls from this clay and glaze combo and promptly sold all of them. About a month or so after selling one of the bowls, I was asked if I could make a mate to one of them and much to my chagrin, I realized, I had misplaced the test notes. I only recently found the notes to that particular conundrum and made up 20lbs of the clay and more of the Oribe as well. In a week or so, I should see if the pieces come out as they did before. I say this because I have taken explicit notes before and when trying to reproduce the results, the pots were just not the same. Most likely some variable that I over looked, but sometimes, inexplicably, the results are just not possible to reproduce, kismet maybe?