Today we finished our second ever batch of rocks in a rotary rock tumbler. The results were surprising and I'm in love with the rocks.
To get these rocks done, I went against every fibre in my environmentalist, scientist heart (and against the prevailing advice of experienced tumblers) and I used plastic media in the last two stages to cushion the rocks. Here is a breakdown of that experience in some key take home points:
Pros of plastic media
It was there. That's it. The only positive. It came in a rock tumbling grit kit (I would not have bought it separately). I needed filler and I didn't have enough ceramic media in a pre-worn state. I used what I had.
Cons of plastic media
It's a pollutant. Plastic media is synonymous with nurdles, those little precursor plastic pellets used to make larger plastic items that every so often gets a mention in the media as a pollutant that washes up on beaches. Having worked with it, try the best you can but that stuff gets everywhere. It is a nightmare. I'm still finding bits all over the house, despite my best efforts. And some of it has escaped into the wild.
It's a source of pollution. The beads got smaller in the course of grinding, but plastics don't vanish down into nothing. Through rock tumbling I was generating microplastics and nanoplastics, and there is a growing body of evidence that these small particles are bad news for us and the environment.
It's reuse is limited. Unlike ceramic media, which can be washed and shoved through multiple tumbling stages, plastic media will become contaminated with whatever you run with it. If you want to reuse it, you can only run it in the same (or coarser) grit.
It's a nightmare. Some people say it's easy to use. I found it more than tripled the amount of time I spent cleaning. It got embedded in the sides of the tumbler and I had to physically pick out individual pellets with my fingers. It got stuck in any gap possible in the colander or under the lip of the strainer. It stuck to anything it came in contact with. Fingers. Sides of containers. Rocks. Sieves. Anything it fell on. And of course, trying to remove pellets and get then into a container often meant stray bits flew onto other surfaces and were a nightmare to pick up. It's hard to clean. It's hard to dry. Little escapees keep showing up even now.
I tried to save my used pellets and still have washed, used ones that could be reused. The thing I have been looking forward to for weeks was somewhat ruined by my experience with these, so I probably won't be using them again.
If you are new to rock tumbling, avoid. Use ceramic media or other alternatives. They are not worth the time or money.
