Getting the perfect surface on your clay pieces is often a combination of choosing the right materials, smart timing of tasks, and knowing which is the best tool for the job. In today’s post, an excerpt from the May 2014 issue of Ceramics Monthly, John Dadmun shows how to make a low-tech sanding tool to help with at least one part of that equation- Jennifer Poellot Harnetty, editor.
While wet sponging is best to smooth a surface as it creates little to no dust, it doesn’t always solve your surface issues. When working with paper clay for instance, using a wet sponge to smooth out dry greenware can result in lumpy, undesirable surface textures due to the paper pulp/fibers in the clay. With a grogged clay, a wet sponge will bring all of the large particles to the surface, leaving you with a rough lip or rim.
A scrap of sanding screen (typically used to smooth joint compound in construction), or foam sanding block, is often the go-to tool when the sanding need arises. Sanding blocks, however, obscure one’s view of the work, fill with clay fast, and offer little in terms of tactile feedback. We can do a bit better, in terms of utility and predictability, by constructing a bow sander from sanding screen and some scraps of wood. With a sanding screen, you can see right through the screen, unobstructed by your hand, and you can sand large curved surfaces with uniformity.
Dry sanding is often a method many potters shy away from because the dust released into the air can be harmful to breathe in and settles onto surfaces everywhere, only to be kicked up eventually and breathed in again. Inhaled dust can aggravate allergies, cause difficulty in breathing, and eventually if inhaled excessively for many years, may lead to silicosis. Therefore, when sanding dry clay, always wear a professionally-fitted dust mask, work in adequate ventilation or outdoors, and use a wet sponge and a wet mop to clean up the dust.
Building a Sanding Bow
Cut out a bow-shaped scrap of wood approximately 5×5¾ inches with each end cut at about the same plane (1). For each bow, cut a sanding screen to fit across the two ends. Make it about the same width as the bow frame and extending at least an inch or so over the far edge of each tip. You can vary the width of your strips depending on the project. Lay the sanding screen across the two ends of your bow and tape around that last inch or so of overlap, fixing the screen around the first inch of each tip (2). You want the screen to be taut but not too tight.
Spread some glue across the top of each of the bow tips where the sanding screen passes over the top of each tip (3–4). The glue should seep through the screen and into the wood. Let this dry, then hit it with a second layer, again letting that dry. If you work with enclosed forms (like handles on mugs), leave one side taped but not glued. You are leaving the face of the tip covered by the sanding screen, but without any tape on it. The sanding screen should give slightly when pressed to the surface, affording great sanding control. Tape it such that a bit of tension exists between the two tips (5). Remove the tape on the glued ends, and cut off the extra inch or so of sanding screen that was taped over earlier.
Using the Sanding Bow
To sand inside a closed area, remove the tape from one end of the bow, slide the screen through the piece, then re-secure the tape. For cylinders, leave a little extra slack in the sanding screen strip. Use the thin edge of the tool to finish crevices (6–7). Remember to rinse out your bow sander occasionally as a full screen doesn’t work as well.