Making and Knowing
A minimal edition of BnF Ms Fr 640 in English Translation

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Casting earth for founders

It becomes fat by being beaten and also mixed with horse manure. Potter’s earth would be too soft and would break and wouldn’t resist the fire. But [your soil] has to be mixed with one half of sand and a quarter or a fifth of horse manure. And leave it to dry, then reduce it to powder, then put it through a sieve to make it fine and free from gravel, which would prevent it from casting cleanly. The manure makes the earth more amenable [to casting] & easier to work with, but it should be free of straw and other things. And when the earth is very fat, you have to add more sand and more manure. But one does find fat varieties of earth [that are] naturally mixed with sand. If they are not, make them so artificially. One should always cook the soils again before casting.