Guidelines for Altering Straight-Sided Cylinders

deb_350Darting pots is yet another thing on my long list of to-dos in the studio. I love the way simple darts can really change the look of a piece and give it personality. In today’s post, an excerpt from the Pottery Making Illustrated archive, Deb Schwartzkopf provides some tips for altering straight-sided cylinders. Her handy-dandy illustration of what forms are created by different darts is really helpful in visualizing the final result. – Jennifer Poellot Harnetty, editor.


deb_graphLearning to dart and alter thrown forms can add dramatic results to traditional forms. If you’re willing to experiment and test the limits of what you thought was possible, you may find yourself surprised by the results. Straight-sided bottomless, cylinders are a good basic form to start practicing alterations on. Alterations lead to less cracking when clay is just barely dry (not finger printing, but still flexible). A bottomless cylinder allows the entire form to take on any shape you choose. It’s possible to use darts on cylinders with a foot as well. When attaching the edges left after removing the dart, the rim, and foot may extend out further than the original form.

A. A long, narrow, tapered oval dart

1. If the dart ends close to the rim and does not extend through it, the rim is likely to strain and be prone to cracking. Compress it and add supportive clay by scoring and slipping it into place. Score and slip all seams.

B. A wider, shorter oval dart

2. When trying to determine how to cut a dart, remember the wide part of the dart is where the cylinder will move toward its center the most.

3. When a dart ends mid-wall, it creates a point. The more dramatic the taper of the dart, the sharper the point. If you don’t want a point, the dart must taper more gently. The more dramatic the dart, the more the walls of the cylinder stretch and change, leading to greater risk of cracking, especially when using clay that’s too dry.

C. Triangular or half-oval darts

4. Darts can be taken out of the top or bottom of a cylinder. When a dart is taken out of the form’s stance, it will have more lift.

D. Tapered, triangular darts

5. This is a more complex cut. The horizontal cut that extends beyond the vertical dart allows the walls to move toward each other, narrowing the entire upper section of the form and forcing the cylinder to become oval shaped. At the top of the upper tuck it’s difficult to get the walls to meet well. I add clay at this joint to prevent cracking. I use a combination of these cuts and darts to augment many different thrown and slab-built parts. Check out the image to the right. See if you can figure out which steps led to the pitcher’s shape. The piece started as a straight-sided cylinder with a slight curving volume.

To download Deb’s PDF on Altering Straight-Sided Cylinders, go to

**First published in 2015
  • Kelly M.

    I’m thinking B for the spout area, C for the foot near the spout, and D for the handle area…?

  • Twyla S.

    This is great information. As I go to the next level in ceramic sculpture this may come in handy. Please continue to pass on information to us all. Thank you very much.

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