Mocha Diffusion Preliminary Experiments

A week or so ago I had the opportunity to watch several free videos from various clay artists around the world. Two of the videos inspired me to do some experimenting. The first is a slip decorating technique called mocha diffusion. Mocha Ware Pottery was invented in the United States and England in the late 18th century. The term mocha does not refer to coffee but to the dendritic patterns emulating the moss agate or mocha stone. Basically the slip (liquid clay) is poured on a pot and then an acidic ingredient is mixed with a colorant and dropped onto the slip. The diffusion occurs because the acidic ingredient is repelled by the alkaline ingredient which is the liquid clay or slip. Some of the first mixtures in England and the United States used tobacco juice as the acidic ingredient.

I made my slip from my clay body. I let the clay dry completely in little pieces and when completely dry added water and let the clay particles slowly absorb the water. Then I blended the liquid clay with a mixer and sieved it several times to be sure the mixture was smooth. I didn't want to waste clay bowls so I decided to try my preliminary experiments in a glass bowl. First I tried mixing stain with wine and it didn't do a thing. To be fair the slip was too thin. I let the slip sit for two days and siphoned off the excess water which floated to the top. Then I tried mixing oxides and unfiltered apple cider. Copper carbonate didn't work, but nickel oxide worked fairly well. Above photos show the results of RIO (red iron oxide) which did the best. Stay tuned for more experiments from my studio. Thanks for reading and for all your comments.