Why Use Tumbler Media? Tumbling media has four functions: 1) it delivers grit to hard-to-reach rock surfaces; 2) it is used as a filler when tumbling a partial load; 3) it is used to cushion fragile rock materials during the tumbling process; and, it is used to improve the tumbling action in the tumbler barrel. Plastic pellets are to be used only in rotary tumblers (they produce too much "bounce" in a vibratory). Ceramic pellets are mainly used in vibratory tumbling but many people use them in rotary tumblers instead of ceramic media. If you are tumbling a load of large rocks they will have very few points of contact. However, if you add ceramic cylinders to fill the voids between the rocks there will be a lot more points of contact where grinding action can occur. The result will be faster grinding and smoothing done on surfaces where rock-to-rock contacts would not occur.
Large ceramic pellets work great as a filler and for delivering grit or polish to difficult-to-reach surfaces. They also improve the tumbling action when you have larger rocks in the barrel. These angle-cut cylinders are approximately 3/8" (9mm) diameter x 5/8" (16mm) long. They can be washed and carried from step to step of the tumbling process along with your rocks. Large media will last through many tumbling cycles. When they wear down to a smaller size you can use them in place of small ceramic media.
Small Ceramic Tumbler Media
We use these for cushioning!
Small ceramic pellets work great as a filler and for delivering grit or polish to difficult-to-reach surfaces. Running easy-to-bruise materials like obsidian and crystalline quartz with 50% small media can significantly reduce the bruising that they receive in the tumbler. In the polishing step lots of small cylinders will brighten up your polish. These angle-cut cylinders are approximately 3/16" (5mm) diameter x 3/8" (10mm) long. They can be washed and carried from step to step of the tumbling process. When used in the fine grit and polish stages they will last through many tumbling cycles.
Plastic Pellet Tumbler Media
Rotary Tumblers Only!
Plastic pellets cushion fragile stones in a rotary tumbler and can be used as filler. They are about 3/16" (4mm) in diameter and float for easy separation from the rock. They can be reused many times in the same size grit. Some people still use plastic media. We now use ceramic media because it stays with the rocks through all steps of the tumbling process.
A video showing use of the different tumbling medias above
What Type of Media Do We Use?
We used to use plastic pellets exclusively, then we learned about ceramic media. It was a good day.
Plastic media has to be captured and stored because it is really hard to clean. If you use plastic media in fine grit you can't use it later in polish because some of the fine grit might be carried along. Similarly, if you use it in medium grit you can't use it with fine because some of the medium grit might contaminate the fine step.
With ceramic media, you can rinse it with the rocks and it stays with the rocks all through the tumbling process. We use mostly large ceramic media because it will become small ceramic media after a few batches of tumbling.
Bonus Media :-)
We also use small Lake Superior Agates (or any small round stone that needs a little more tumbling) as media because they are round and really really hard. They persist in the tumbler for weeks and weeks and if we use them as media we get a bonus of some nicely polished stones instead of some nicely polished media.
We have a red plastic "media" bucket into which we place all washed and dried media that is ready for another run. We add to that bucket any small stone that needs a little more attention. A few days or a few weeks later that stone is perfect :-)