We’ve done a lot of articles on inlay ceramics—often called slip inlay or Mishima—here on Ceramic Arts Network. Here’s a good introduction to Mishima pottery if you’re unfamiliar. Typically Mishima is used to create very fine lines on pots by using a sharp blade to carve lines, filling the lines with colored slip, and then scraping off the excess slip to reveal the fine inlaid design.
Sumiko Takada preferred a wider line for her slip decoration but she didn’t want the lines to be raised like they are with slip trailing. So she started experimenting with inlay ceramics. In this post, an excerpt from the Ceramics Monthly archives, Sumiko shares her version of inlay ceramics: carving lines with a small clay ribbon tool, filling them in using a slip trailer, then scraping away the excess revealing her beautiful and smooth designs. – Jennifer Poellot Harnetty, editor.
Slight variation on inlay ceramics creates wider flush lines
I prepare stencils of pattern designs on tracing paper using pencil (1). The sizes and proportions of the patterns are adjusted depending on the shape and scale of the pieces. Though I have favorite pattern designs, I am always looking for new ones and regularly add two or three new patterns to my repertory.
Grid lines are drawn as the reference on trimmed, leather-hard pots (2) and then patterns are transferred on the piece using a needle tool with a rounded tip (3). I apply just enough pressure to draw lines on the paper without tearing it. I can usually use a paper stencil over 20 times.
Carving starts with tracing transferred lines with a needle tool to make them deeper. Then a double-ended ball stylus and small wire loop tool are used to make the pattern wider and deeper as the leather-hard ware dries (4, 5). Generally speaking, the carvings are linear and their depth is no more than 1⁄16 of an inch. Wider and deeper carvings may result in cracks between the body and engobe. I pay close attention when drying my work and with the timing of carving as it is hard to make clean lines with an even depth and width on the surface if it is too soft or too dry. Depending on the sizes of pieces and the complexity of patterns, it takes a few hours to a few days to complete the carving.
After the carving is completed, engobes are applied with a fine-tipped slip trailer (6). Over the years I have tried different types of trailers but the inexpensive plastic trailer seems to work best for me. With metal ribs, I do an initial cleanup of excess engobes when they are drying but still softer than the clay underneath, which makes the engobe easier to remove (7). When the engobes dry to the same stage as the clay, the final cleaning is done carefully without disturbing the surface (8).