Quick Guide to Rock Tumbling
What Is Rock Tumbling?
Polishing rocks is both a science and an art form. Rocks and minerals in their raw form come in various sizes and conditions; the tumbling process grinds away the rough exterior to reveal the beauty within. By placing the rocks inside the tumbler along with the appropriate amount of rock tumbler grit and water, you will eventually see the results of your work after a period of time. Indeed, rock polishing takes patience, but the rewards can be great.
When my husband first expressed his interest in tumbling rocks for a hobby, my response was one of confusion. Obviously, I was unfamiliar with lapidary work, or rock polishing in particular. I suppose that I considered it the domain of professional jewelers rather than a practical hobby for home. However, I have since begun to see it as a not unusual undertaking. Over the past couple of years, I have learned to view my rock hound husband and his work in a different light. Perhaps you too will read this article and see lapidary in a new way, maybe taking on rock tumbling as a pastime of your own.
Terms Used in This Hub
As this is an article for beginning lapidarists, I am using the term “rocks” to refer to all rocks and minerals. For more information on the scientific definition of each of these terms—along with other terms related to specific rocks and minerals—please see your favorite guide to lapidary.
Who Might Be Interested in Polishing Rocks?
Lapidary work is not the sole domain of the rock hound. Rock tumbling can appeal to a wide variety of people for different reasons. What sort of people might enjoy rock polishing?
Families will find this an educational activity that can be undertaken together. Identifying and choosing rocks, putting the rocks in the tumbler, and finishing the process can be done as a family.
Those interested in making their own jewelry may decide that choosing their own gems and tumbling them would help them create truly unique items.
Homeschoolers might find this an interactive way to learn more about geology.
These are just a few of the different types of people who might be interested in this pastime.
Vibratory Tumbler in Action
Gem and Mineral Clubs
One resource to look for in your area is a gem and mineral club. These clubs can be a valuable source of information for those just getting started in lapidary.
Choosing Rocks for Tumbling
Barring a knowledge of your local terrain and the available rocks, perhaps the simplest way to find rocks appropriate for tumbling is to purchase them at a local lapidary store. If you are fortunate enough to have one in your area, then you will be able to benefit from the owner's expertise in the field. They should be able to provide you with not only rocks but also the necessary equipment and supplies. Becoming a regular customer of a lapidary store and creating a relationship with the owner will ease your way into this new hobby.
If you are not so lucky, then you may want to begin your search for rocks online. Kingsley North is one reputable and well-known site for both rocks and lapidary supplies. Another source might be Amazon. However, we have found that the sellers there offer their rocks for almost double the price found elsewhere. Also, many of the sellers are offering rocks that are more suited for aquariums than polishing. The cheapest source that we have discovered online is eBay. Before you become acquainted with a seller and their product, purchase rocks in smaller quantities. Once you find a good seller, then you can always buy more of their available rocks for tumbling.
So what rocks do you choose if you're a beginning lapidarist? Quartz, chalcedony, jasper, and agate are good choices as they are all in the same family of rocks and are therefore of similar hardness. The Mohs scale of mineral hardness will help you choose the kinds of rocks you should be tumbling together. Choosing rocks of similar hardness makes them easy to tumble to a nice and shiny finish. By picking rocks from the same family, you will make your first tumbling experience that much more rewarding.
Choosing a Rock Tumbler
Perhaps an even bigger choice than the selection of rocks is the purchase of a tumbler. Tumblers can be relatively cheap or extremely expensive depending on the type and brand. Your choice will depend on your personal budget as well as the particular qualities of the two types of tumblers, rotary or vibratory.
Rotary tumblers consist of a rubber barrel that holds the rocks, grit—or tumbling media—and water, all of which rotate at a slow speed. These rock polishers are easy to use but take quite a bit longer to produce the finished result. The process of tumbling in a rotary tumbler results in rocks that are more rounded, and generally the rocks lose about 30% of their original volume in the tumbling process. You can expect the entire process to take at least a month or more.
Vibratory tumblers are donut shaped and work as the name suggests by vibrating rapidly. The rocks move, rotating around the bowl, and cycle from top to bottom repeatedly. This type of rock polisher produces rocks that are closer to their original shape, retaining more of the original rock. One benefit of the vibratory tumbler is that the process of polishing rocks takes a fraction of the time of that of a rotary tumbler. Rocks can be finished in a little more then a week, unlike the month or more required by a rotary tumbler.
When buying a rock polisher, it is important to consider the quality of the machine before purchasing it. These are usually big investments, and so choosing the best machine for your budget is important. Two of the better brands are Lortone and Thumler. The tumblers made by these two companies are dependable and reliable, and it is easy to find replacement parts for them. Whether rotary or vibratory, any tumbler produced by either of these companies will stand up to the constant wear of polishing your rocks to a nice finish.
What is your favorite kind of quartz?
Supplies Needed for Rock Polishing
The following is a general list of supplies that you will need for tumbling rocks:
Rocks for tumbling
Various grades of grit
Polishing powder for final stage
Plastic bucket for cleaning out the rocks and tumbler slurry
Some kind of wire mesh for straining the rocks from the slurry after tumbling
Example of Supplies for Rotary Tumbler
Some Tips for Having a Successful First Rock Polishing Experience
Do not pour the slurry that results after the rock tumbling and polishing down your drain as it becomes a cement-like substance that will clog your drains.
The stones should all be similar in hardness.
You may need to add a filler material—whether plastic or ceramic pellets—as you go through the stages because the original material will be ground away.
It is important to clean all the grit out of the tumbler and rocks between each stage.
Rocks in Vibratory Tumbler
Stages of Tumbling Rocks
Your tumbler will come with instructions for tumbling the rocks during each of the following stages. Always read the manufacturer's instructions carefully before beginning your first rock tumble.
The four general stages for rock tumbling are below:
Each of these stages requires a different grit to further polish the rocks to a desired finish. Your tumbler will most likely come with a small sampling of the different tumbling media and polish, but you will eventually need to find a resource for purchasing these materials, whether locally or online. These different media must be used in the correct order as suggested by the manufacturer in order to produce the right result. Additionally, the times for each of the stages will be different depending on the type of tumbler as well as the rocks; a general guide to the times required for completing each stage should also be included in the manufacturer's instructions for the rock polisher.
Wire-wrapped Pendant Made with Polished Rock
No matter your reason for beginning this pastime, rock polishing can be a rewarding hobby. There is much you can learn about gems and minerals, and the process of revealing their beauty can become a new passion. Indeed, once you become a rock hound, you may find that you have a lifetime devotion to the art of turning rough rock material into beautiful, natural works of art.