Though it might sound like a fancy coffee drink, mocha diffusion is a little-known technique of ceramic surface decoration developed and used in the southwest of England. Through a reaction between acid and alkali, intricate veined patterns reminiscent of trees or ferns are created in this process.
A while back, we posted an excerpt from Ceramics Monthly, in which Canadian potter Robin Hopper provided an explanation of the technique and a slip recipe that works well with it. Since then, Robin has recorded a new DVD. Today I am sharing an excerpt from that video, in which he demonstrates mocha diffusion and his slip dotting technique. I have also reposted the original article with the slip recipe below. –Jennifer Harnetty, editor.