Third or fourth pass grinding barley on a metate
Lots more questions than I can take up. But one that several commentators have raised is “Why did the simple grindstone survive until now in Mexico when in many parts of Eurasia it was abandoned about two or three centuries BC?”
First, the Mexicans did take up the rotary grindstone at the time of the Conquest. Water mills were constructed at great expense wherever there was water sufficient to run them. So it was in no way ignorance of rotary grinding. Rotary grinding was for wheat though.
Which raises a point that I think has to be borne in mind all the time we are talking about early grain techniques. To most of us, grains are things in bins in the whole food store, pretty much of a muchness. In the past, what now appear to be small differences among grains made huge differences in how you processed them and what you turned them into.
And, thus second, the differences between wheat and maize were big differences. You can of course grind maize with a rotary grindstone. That’s how it was done by the American colonists, by Europeans and by most of the others who accepted maize. That gives you corn meal. And unless you add other ingredients that is most easily eaten as a gruel or porridge.
But Mexicans had at least five hundred years of eating tortillas (and many more of eating other maize products). And the maize for tortillas is treated with alkali, brought to boiling, cooled and drained before grinding. That is it is wet ground (a technique also used in South India).
I believe that it is impossible to wet grind on horizontal rotary stone mills. I have been trying for years to get a rotary mill to test this hypothesis but no luck thus far. Any ideas gratefully received. But it is my belief that instead of flowing out through the grooves cut in the lower stone, it would simply gum up.
Since tortillas are so central to Mexican ways of eating, they kept using the metate.
Third, the “simple” grindstone or metate has lots of advantages over rotary grindstones more or less whatever you are grinding. It is cheaper. It does not require a highly skilled professional (a professional nonetheless) to make it and keep it in good condition. It’s best made with basalt of which there’s lots in Mexico. It produces a better product I am almost certain. And it can be used for lots of things.
It’s really only in efficiency that the rotary mill wins. A big consideration of course but mainly if you highly value the labor of the grinders. Otherwise it produced a product thought of as cheap and nasty.
As an aside, many, many thanks to the many Mexican women who have shown me what they can do with a metate and patiently watched my fumbling efforts to imitate them.