New squash balls have a dark black color and a slightly grippy texture. After they have been used for a while, they become smoother and lighter colored. Everyone likes playing with a new squash ball, but they're a bit dear at $4 or $5.

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In order to rejuvenate them, some players rub a used ball on a fabric chair seat which does a halfway decent restoration job. Ballchemy sells a little 3D printed device which uses sandpaper to resurface a ball. I bought one and it's a nice alternative to the chair seat. It was a little difficult for me to grip the circular base and the ball, so I printed a modified one. The new one has straight sides with depressions and a height less than the squash ball's radius. So it is easier to hold both the device and the ball.

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The squash club where I play has buckets of used balls available for reuse. I wondered whether these could be restored in bulk by tumbling them with sandpaper. I made a tumbler using a pretzel container, an improvised roller and a small lathe.

I tried tumbling some balls with loose 120 grit powder. This did not work at all and it looked like grit was becoming embedded in the ball surface. I also tried tumbling the balls with small squares of sandpaper. This also did not work.

I happened to be washing some squash balls to use as placeholders for a dinner and noticed that just washing them did a pretty good job of making them closer to new. That encouraged me to try tumbling the balls with dishwashing liquid. I also included some cut up green Scotchbrite pads. I tumbled them for a half hour and this worked very well. The balls emerged beautifully clean and textured. They also felt a little sticky. Playing with them felt like playing with new balls.

In order to prevent soapy water from escaping the jar, it is better to use non-sudsing dishwasher powder instead of dishwashing soap. I'm sure there is wide lattitude in the details, but what has worked for me is tumbling two dozen balls with about three inches of cold water, two tablespoons of Cascade powder and two green Scotchbrite pads cut into rectangles around two inches on a side. This is tumbled for a half hour and then the balls are rinsed.

A detail: I made a gasket for the lid of the pretzel container from a piece of rubber. I started out using hot tap water because I thought it would clean better. But as the water cooled, it created low pressure which sucked the gasket into the container enough to cause a leak. Using cold water fixed that and does a fine cleaning job.

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