Making a Pottery Ruler
Steps to Make a Pottery Shrinkage Ruler
Prepare the Clay: Roll out a slab of your regular pottery clay to about 0.5–1 cm thickness, roughly 30 cm long and up to 5 cm wide.
Mark the Ruler: While the clay is soft or leather-hard, use a ruler and needle tool to scratch accurate centimeter or inch marks along the edge.
Label and Detail: Scratch the clay type, date, and, if known, the firing temperature (e.g., "Cone 6") onto the ruler.
Dry and Fire: Allow the ruler to dry slowly to prevent warping, then bisque fire it. Use weights to stop the ruler from warping.
Highlight Numbers [Optional]: After bisque firing, apply underglaze to the scratches to make the measurements easier to read.
Using the Ruler
Measure Shrinkage: Use the fired, shrunk ruler to measure your wet pots. If the ruler says 13 cm, the final pot will be 13 cm after firing.
