Rock Tumblers Redux: Looking at the Stages of Tumbling

Several weeks ago, I posted an entry to the blog about how to work with your new rock tumbler (this of course assuming that you had received one at some point). Six weeks into my own experimenting with rock tumbler, I'm back with a few lessons and things that I've gleaned from my own experience, which I hope will be helpful to you.

Tumbling is typically a multi-week process, depending on the materials that you choose and the kind of polish that you are hoping to achieve. The choice of materials is important, as tumbling something rather hard with things that are soft will tend to result in the soft things being smashed down into tiny bits. To be certain of the hardness of the materials with which you are working, it's essential to have either a good rock & mineral field guide (I've got about a half dozen), all of which will give you the hardness of most anything you are likely to be tumbling, as presented by the Mohs Scale of Mineral Hardness, which ranges from 1 (talc), to 10 (diamond). If you pick up a field guide and it doesn't have this basic information, put it back on the shelf and find something else. You can also use online resources to determine the hardness of your material: the most thorough of which I am aware is Mindat, which is currently a free site (although with a free registration you can have access to more features). Even with care taken in selecting which minerals and rocks you tumble, you should still expect for anywhere from a quarter to half of the volume to disappear into your slurry bucket.

Polish is also a consideration: some people will like their stones to have different lustres, so it does come down to individual taste. Personally, I want to see just how brilliantly reflective I can make some materials, so I am experimenting with a range of stone.

Assuming that you are indulging in a basic four week-long process, you will also want to choose your grits with care. Before I'd started working with a tumbler again - after a gap of many years - I had expected that four standard grits made of silicon carbide would be sufficient, and hadn't really understood the importance of the pre-polish and polish phases. I can now tell you that these are crucial (this probably should have been self-evident). The pre-polish and polish phases, both accomplished in my case with very fine aluminium oxide polishes, are essential... if you want your tumbled stone to shine, that is.

Time is also an important variable. Your tumbler should come with a guide, or you can find them on the web with relative ease (also in my last post). On my first attempt through the whole of the process, I allowed at least a week for each tumbling stage. This may have been overkill, but on the other hand, I was recently told of a man who left his rough in the final polish phase for something on the order of six weeks! This is probably unnecessary, at least at first. Follow the guides to begin with, until you will get a sense of which materials will require longer than others in the various stages. Again, this often comes down to personal taste.

One thing that is somewhat annoying is that, for the cleaning phase, the use of Ivory Snow flake detergent is often recommened, at least in North American guides. Unfortunately, this product no longer exists. However, if you can't find another plain, pure, unscented soap, the workaround is simple: find a bar of Ivory Snow soap (which does still exist), or any other basic unscented Castille-type soap (Pure & Natural also comes to mind), and use an old cheese grater to make your own flakes. It may help to dry the soap out a bit first - put it in a warm, dry place for a few days, then grate. You will now have soap ideal for use the cleaning phase of tumbling.

Rock tumbling seems, in the shiny new digital 21st century, like something of an anachronistic pursuit, and perhaps it is. But it is also one which connects us with the realities of making something, of doing something, rather than simply paddling around in the virtual pool. Hopefully, you will take as much enjoyment from it as I am.