Concentric Coaster

The Concentric Coaster is a cast concrete drink coaster. The top is a field of concentric grooves, and the grooves do the work. Condensation from a cold glass runs down into them and gets held there instead of pooling out onto the table, slowly soaking in and evaporating. A bonus, it’s heavy enough to stay put when you lift your glass, instead of coming up stuck to the bottom.

It grew out of the same concrete work as the Cord Keeper. Casting one simple object taught me the material, and this was the next thing to try. Sold as a set of four.

Making it

The ridge pattern started as a 3D print. I modeled the concentric texture, printed it, and used that print to make a silicone mold. More specifically, the 3D printed pattern was made by the SLS (selective laser sintering) process, which is known for it’s powdery texture, and perfect for the concentric coaster. From there it’s the usual concrete process: mix, pour, vibrate the bubbles out, cure, demold, and sand by hand. A cork base goes on the bottom to keep it off the table surface. Each one comes out a little different.

Colors and a collaboration

The first runs were natural grey concrete and white. Then Annie at Seed & Arrow started hand-painting color blocks across the tops of some. Those became a limited edition we brought to Renegade Craft in Chicago and Good Day Market here in Madison.

It was a popular product, sold as a set of four at markets and shops and got a writeup in Madison Magazine.