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The making of Tandoor ovens seems ordinary to someone from a country where they are made. But it seems impossible to me (based on my lifetime experience working with clay). I would love to learn from someone in India the answers to these questions (based on the video links below), can you please message me if you can help?
-Clay shrinks when it dries. The more water it has the more it shrinks. When it dries unevenly it shrinks unevenly. Uneven drying means it cracks. The rim on these Tandoors should dry and become rigid long before the bases. Cracks should thus occur part way down the wall as the base tries to shrink against the already-dry rim. Why is this not happening?
-Dried clay is not rock hard, it can be turned back into mud if it gets wet. Why don't those ovens disintegrate in the rain?
-To do what the craftsmen and women do with the clay it would need to be very plastic (and thus have high drying shrinkage). Where the crew is building the six ovens beside the carriage the friction and drag on the ground should cause them to form cracks from the ground upward. Or they should pull to an oval shape. Why does this not happen?
-Wet clay cannot be joined to dry clay. The wet clay needs to shrink. How is it possible they are doing exactly this?
-Am I underestimating the degree to which the straw addition reduces the shrinkage of the clay? But plastic clay needs to shrink 10% whether there is straw or not. How can this work? Even if the straw could cut shrinkage to 5% that is still 1.5 inches on a 30 in diameter Base.
-Are they using a body high in ball clay? How else could the clay be plastic enough for this work if not?