Clay and Slip for MishimaBoth the clay and the slip (or underglaze or soft clay) that is used should have fine particles without inclusions. Clay bodies with grog, sand, paper pulp, or other additives are not good candidates, as those particles will make it much more difficult to get a smooth, flush surface when the excess material is removed.
Carve the Mishima DesignCarving a design is the first step in the mishima technique. Generally speaking, it is easier to get cleaner lines when the clay is a medium to stiff leather-hard. This, however, can cause problems as the clay body and inlay slip or underglaze have different moisture contents. This difference can cause cracking and poor adhesion between the two.
If you do allow the main clay body to stiffen first, once the contrasting slip is applied, slow the drying speed down considerably. Cover the piece with plastic or place under a slightly raised bucket to help even out the moisture content and slow the drying.
If possible, carve the clay as soon as possible. As you can see in the example photograph, there are likely to be lifted edges and loose bits and pieces as you do this. Do not clean the piece up as you go.
As you incise or carve, keep in mind that you will be removing some of the surface clay as well as the excess slip. Make your incised lines deep enough that the inlaid design will not be erased during the clean-up process.
Tools for incised lines will depend on how you wish the piece to turn out. In the example, I am using a mini-loop tool to remove clay, resulting in a thick-and-thin design reminiscent of calligraphy. Other line characteristics can be achieved by using any number of other tools such as pencils, sgraffito tools, loop and ribbon tools, small sticks, and so on.