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Rock Tumbling Tips

Rock tumbling is the process by which gemstones are polished. The stones are placed in a barrel that is mechanically rotated. Small material that is very hard and coarse, called grit, is placed in the barrel with the rocks along with water. The barrel is rotated, which causes the rocks and grit to tumble together in the barrel. The grit wears down the rocks, which smooths them out. Eventually, the rocks are tumbled with softer material, usually plastic pellets that polish the rocks to a high shine. Here are some tips for tumbling your own rocks.

Tumbling
- Use separate rock tumbling machines for each step of the process. Different sizes of grit are used in each step and if the wrong size grit contaminates a step, the rocks will not smooth out like they should. Using separate machines reduces the chances of contamination.
  If you are running more than one rock tumbler machine at a time, keep a written record of when you started each machine and all the other pertinent details.
Cleaning
- Clean the rocks carefully between each step. This will also reduce contamination of the grit. When you are cleaning the rocks, never pour the leftover slurry down the sink. This can harden in your pipes and cause a blockage.
Polishing
- For an extra shine on your rocks, add a tablespoon of sugar to the final polish. You can also add a tablespoon of washing powder to the final polish. This will help the polish glide more smoothly over the surface of the rocks.
Tumbler Machine Care
- Make sure to oil the bushes on the tumbler as often as the manufacturer recommends. Otherwise, the tumbler will wear out quickly and will have to be replaced often because it will have to be running constantly for many days. You can use a syringe to make it easier to oil and avoid putting too much oil on.
  Place the machines in an area where the noise won't bother you or a neighbor. This will save you plenty of aggravation. You may want to place a towel or other cloth under the machines to save the surface you are placing them on. It could also help to dampen the noise.
  Never leave the tumblers unattended for more than two days. You will want to be able to react quickly if a machine motor quits or if a lid becomes dislodged.

Gemology