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How to Use Rock Tumblers for Glass

Rough pieces of glass, such as sea glass, can be polished in a rock tumbler, which requires extra precautions. Plastic pellets, for example, are needed to provide a buffer to prevent chipping and breaking. Although rotary tumblers can shape the glass, vibratory tumblers use a finer grit that polishes glass pieces and prevents pulverization.

Things You'll Need

Rotary tumbler, 3 pound barrel
Tumble rough glass
Plastic pellets
4 tablespoons coarse grit
Water
Colander
Disposable plastic container
Vibratory tumbler, 3 pound barrel
4 tablespoons fine grit
5 tablespoons pre-polish or extra-fine grit
5 tablespoons polish
1 tablespoon Ivory soap bar, sliced

Instructions

- 1
  Select pieces of tumble rough glass between 1/2 to 1 inches that are not pitted or cracked.
- 2
  Measure out equal parts rough glass and plastic pellets. The total volume should fill at least half the barrel and no more than 3/4 with the addition of material in the following step.
- 3
  Add coarse grit and water. Water should reach to the bottom of the top layer of rocks.
- 4
  Wipe down the inner and outer edges of the rim and make sure no water or debris is present, then place the lid securely on the top of the barrel.
- 5
  Place the barrel on the rotary tumbler and turn it on. Watch carefully for 2 or 3 minutes to make sure there are no leaks.
- 6
  Allow the glass to tumble for 3 days then check the shape. If rounded to your taste, you may move on to the next step. For rounder pieces, continue tumbling for a maximum of 7 days. Remember that glass may chip and break the longer it tumbles.
- 7
  Remove the barrel from the tumbler and drain the contents in a colander placed over a disposable plastic container. DO NOT pour the barrel slurry down a house drain. It will clog the drain.
- 8
  Separate the glass from the plastic pellets. Dispose of the plastic pellets. Do not reuse.
- 9
  Rinse the glass thoroughly with water to remove all grit. Excess grit will contaminate later steps and scratch the glass. Set aside any glass pieces less than 1/4 inch.
- 10
  Clean the barrel to remove all grit.
- 11
  Switch to a vibratory tumbler.
- 12
  Add glass and fresh plastic pellets to the vibratory tumblers barrel according to the instructions in Step 2.
- 13
  Add fine grit and enough water to reach the bottom of the top layer of glass.
- 14
  Place the barrel on the vibratory tumbler and turn on. Watch carefully for 2 or 3 minutes to make sure there are no leaks.
- 15
  Repeat Steps 6 through 10.
- 16
  Repeat Steps 13 through 15 twice, substituting the pre-polish then polish for the grit.
- 17
  Add glass, fresh plastic pellets, Ivory bar soap and water to the barrel. Place the barrel on the vibratory tumbler and run for 2 to 3 hours.
- 18
  Empty the contents of the barrel into the colander and rinse.

Gemology