Mocha Diffusion is a very special technique: a process that is almost magical to watch because of the very rapid way that landscapes are formed in front of your eyes.
Whenever visitors come to the studio here at JoVic Pottery, and we have the time to engage with them and show them a few things, a mocha demonstration is often at the top of the list.
Achieving success with the process on pottery often proves very difficult. Everything has to be just right for things to work. The pots need to be almost bone dry. At that stage they will rapidly absorb the slip applied. This slip is quite alkaline. The introduction of an acid can be shown by the addition of colorants to a tea made with boiled pipe tobacco.
If the pots are too dry, the slip just forms ugly blotches and runs. If the pots are too wet, the slip stay wet too long and the “trees” grow well beyond our desired needs right over the edges of the rims. It’s a Goldilocks process, so if the pots are just right, we can quickly make landscape strokes and add a little extra tea in those spots where we’d like a tree to “grow.” We really have a very short window in which to do this decoration and pure concentration is required, as well as a planned approach.
But for our visitors, we have a delightful solution consisting of a piece of plastic that we dip into the slip bucket. The slip stays wet, of course, but almost always works to demonstrate the technique. We watch the trees grow and continue this growth demonstrating not only the wonder of dendrite at work, but also explaining how continued moisture is undesirable on our actual work.
Vic Duffhues has been using this technique for many decades. Yet even with all that experience, he’s not always guaranteed the results he’d like. Now he chooses to exercise this form of decoration only in the early spring, when drying conditions are most easily controlled. The result is that we never have enough mocha pieces and there is always a demand by collectors.
They truly are gorgeous mugs and tumblers and we joke that these are the fastest growing trees in British Columbia.