I've found a few pumice rocks at the beach, from the size of an egg to about a handball. I've boiled them and left them in diluted bleach for a while to disinfect and clean. Now I'd like to cut some of them into shapes which are easier to handle and just generally nicer. As someone unused to cutting rock of any kind, I wonder about the following and just generally how to handle it:

  1. Pumice is brittle, sometimes so brittle that I can break it with my hands. Can I hold it reliably with a vice or clamps?
  2. I've got an angle grinder and a small multi-tool (Dremel). Are both of these suitable?
  3. What sort of angle grinder disc is suitable? Should I use a standard stone cutting one?
  4. How dangerous is the dust? Will I need a simple face mask or more comprehensive protection? One source seems to indicate that only long-term inhalation is hazardous.
  • Unfortunately, "arts and crafts" questions are off-topic here. Please take our tour so you'll know how better to contribute here. – Daniel Griscom Jun 5 '19 at 19:36
  • Pumice is used as a building material and I guess this question could possibly be considered on topic for that, but yeah, I didn't have that in mind. – l0b0 Jun 5 '19 at 20:07

4: It's volcanic glass, so you'll be breathing tiny glass shards, and perhaps getting them in your eyes, so considerable care is called for, or cutting underwater to prevent dust. Water is generally bad for standard angle grinders and Dremel tools, so they may not be the best choice.

2: You can cut it with a handsaw (intended for wood) you don't mind dulling (and/or making rusty if cutting with water, though that can be minimized by carefully and quickly drying it.) I often use a coping saw for this sort of work, since the blades are inexpensive and easily replaced. A hacksaw intended for metal would be another, slower, approach. If you happened to have a wet tlle saw, that would also work.

1: Clamping rounded brittle objects can be difficult, and usually requires a padded clamp and being aware of any shifting due to the forces you are applying when cutting so that you can stop and re-clamp. If using a handsaw you may be able to more safely hand hold the stone with your other hand.

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