i air dried the clay though could have fired, both grey and terra cotta, the slurry has to be very well mixed and watery enough to still be extruded, but stiff enough to stay together once printed, i used the larger nozzles with pretty thick layer heights just because the clay would jam smaller nozzles alot. you'll get a feeling for the slurry, just mix down and test fill the syringe and push it out.
also re-enforced the tubing with other tubing and have some ptfe tube i need to try now since the stock stuff had trouble.
just cleaned up the tubes and stuff after letting them sit for months and it wasn't too bad. i'm planning to try a multi syringe print to make a larger flower pot or vase.