Rock tumbling is a fascinating hobby where you transform rough stones into dazzling gemstones, perfect for crafting, decorations, or simply admiring their natural beauty. At rockscapes.net, we’ll guide you through every step of this rewarding process, from selecting the right equipment to achieving a professional-grade polish. Discover the joy of lapidary and unleash your inner rockhound with the art of polishing rocks, mineral polishing, and stone finishing.
In this guide:
- What is a Rock Tumbler?
- Brief History of Rock Tumblers
- What to Do With Tumbled Rocks
- Where to Find Rocks to Tumbling
- Which Rocks NOT to Tumble
- Types of Rock Tumblers
- Supplies
- Four Stage Tumbling Process
- Common Questions
- Final Thoughts
1. What is a Rock Tumbler?
A rock tumbler is a simple machine that polishes rocks. It works by slowly rotating a barrel containing rocks, water, and abrasive grit for extended periods. The grit acts like sandpaper, gradually smoothing and polishing the rocks.
Think of it as a miniature version of what nature does over millennia! According to Arizona State University’s School of Earth and Space Exploration, natural rock tumbling involves the relentless action of water and sediment, smoothing stones over vast stretches of time. A rock tumbler replicates this process in a fraction of the time.
Here’s a breakdown of the key components:
- Barrel: This is where the magic happens. It holds the rocks, water, and grit. Barrels are typically made of rubber or durable plastic.
- Motor: The motor powers the rotation of the barrel. Look for a motor that’s sturdy and designed for continuous use.
- Grit: This is the abrasive material that does the actual polishing. It comes in various levels of coarseness, from coarse to fine.
Grit levels are crucial for effective rock tumbling, with each grade serving a distinct purpose in refining the stones.
| Grit Stage | Grit Type | Purpose |
|---|---|---|
| Stage 1: Coarse | 60/90 Silicon Carbide | Removes rough edges and shapes the rocks. |
| Stage 2: Medium | 120/220 Silicon Carbide | Smooths the surface after initial shaping. |
| Stage 3: Pre-Polish | Aluminum Oxide | Prepares the rocks for the final polish, creating a smooth, silky surface. |
| Stage 4: Polish | Aluminum Oxide | Provides the final high-gloss polish. |
2. Brief History of Rock Tumblers
How did rock tumbling become a hobby? Rock tumbling machines emerged in the 1950s as a way to transform rough, natural rocks into polished gemstones for jewelry.
The popularity of rock tumbling quickly grew, and by the 1960s, numerous U.S. companies were manufacturing tumblers. Early barrels were made from paint cans but evolved to more durable materials like rubber and plastic. While many companies entered the market, Lortone and Thumler’s stood out and became the leading brands. These brands still exist today, serving both hobbyists and lapidary professionals.
Today, you can also find “toy” tumblers designed for kids, often branded by companies like National Geographic and Smithsonian. These are a great way to introduce children to the wonders of geology.
3. What to Do With Tumbled Rocks
What can you do with your beautifully tumbled rocks? People enjoy rock tumbling for many reasons, from collecting and displaying unique stones to using them in various creative projects.
Here are some popular uses for tumbled rocks:
- Jewelry Making: Create stunning necklaces, earrings, and bracelets.
- Craft Projects: Add a touch of natural beauty to various crafts.
- Home Decor: Use them as vase fillers, planter decorations, or paperweights.
- Holiday Decorations: Incorporate them into festive displays.
- Keychains and Magnets: Craft personalized accessories.
4. Where to Find Rocks to Tumble
Where can you find rocks suitable for tumbling? Rocks ideal for tumbling should be hard, nonporous, and have a relatively smooth surface. Agate and jasper, both common forms of quartz, are excellent choices.
While you can purchase rocks online or at rock shops, many enthusiasts enjoy the thrill of finding them in nature.
Finding Agates
Agate is a popular choice due to its translucence and unique patterns. In the U.S., agates are commonly found in Western states, including Oregon, Arizona, Montana, Wyoming, South Dakota, and Michigan. Coastal areas, lakes, and regions with volcanic history are prime locations.
Tim Blair’s video showcases the excitement of finding agates on rocky Washington beaches.
Finding Jasper
Jasper, another form of quartz, is also widely available. It’s commonly found in Western states like Oregon, Idaho, Washington, California, Arizona, and Utah, as well as Texas and Arkansas.
Consulting a local guidebook can help you identify abundant rock types and the best places to find them in your area.
5. Which Rocks NOT to Tumble
What types of rocks should you avoid tumbling? It’s crucial to consider a rock’s hardness based on the Mohs scale.
The Mohs scale, developed in 1812 by German geologist Friedrich Mohs, measures a rock’s scratch resistance (hardness) on a scale of 1 to 10. Lower numbers indicate softer rocks. For tumbling, rocks in the seven range, like quartz, are ideal.
The National Park Service provides a helpful visual guide to the Mohs scale:
Softer rocks like soapstone and marble, or harder rocks like ruby, sapphire, and diamonds, are not recommended for beginners.
6. Types of Rock Tumblers
What are the main types of rock tumblers available? There are two primary types: rotary and vibratory.
Rotary Tumblers
Rotary tumblers are the most common and best for beginners. They shape and smooth rough rocks during the coarse grind stage, resulting in rounded stones.
Vibratory Tumblers
Vibratory tumblers are less common for beginners and are used for fine polishing rocks that have already been shaped. They don’t alter the shape of the rocks but significantly speed up the polishing process.
For stages after shaping (medium grind, fine grind, and polish), a vibratory tumbler can complete the process in about a week, compared to the several weeks it takes in a rotary tumbler.
Ideally, using both a rotary and vibratory tumbler allows you to shape rocks in the rotary tumbler during the first week and then switch to the vibratory tumbler for the remaining stages.
If you’re buying your first rock tumbler, opt for a rotary model.
Best Rotary Tumblers
Rotary tumblers vary in size and price, depending on the amount of rocks you want to tumble at once. Sizing is expressed in pounds, with a three-pound tumbler holding about two pounds of rock.
Double-barrel rotary tumblers are available, which are excellent for tumbling different types of rocks with varying hardness levels simultaneously. Always tumble rocks of similar hardness together, especially during the polishing stages.
Having a double-barrel tumbler is also useful if you have two batches of rocks in different stages of the tumbling process.
However, if you want to tumble a larger amount of rocks as one batch, a single barrel that’s double the size is easier to manage.
Lortone and Thumler’s are the leading brands to consider when buying a rotary rock tumbler. The most popular Lortone tumbler for beginners is the 3A Single Barrel rotary.
The most popular beginner rotary tumbler from Thumler is the Model T 3lb single barrel.
Thumler’s also makes the Model B, a popular mid-sized tumbler. Both the Lortone 3A and Thumler’s Model T are excellent choices for beginners.
7. Supplies
What essential supplies do you need to start rock tumbling? After selecting your tumbler, you’ll need:
Grit
Starting with a simple four-step process is best: coarse, medium/fine, pre-polish, and polish.
The grit types for each stage are:
- 60/90 silicon carbide: For initial grinding and shaping.
- 120/220 silicon carbide: For smoothing the surface after shaping.
- Pre-polish aluminum oxide: For preparing rocks for the final polish.
- Polish aluminum oxide: For the final polish.
Refer to your tumbler’s instruction manual for the exact grit type.
You can purchase all four grit levels as a kit from a local rock shop or online at Amazon.
Plastic Pellets
Use these for smaller loads to fill the barrel. They help distribute polish and cushion rocks, speeding up the process by encouraging tumbling. Pellets can be reused but should only be used in rotary tumblers.
Alternatively, some use corn or walnut shells. Advanced rockhounds may invest in slab saws, trim saws, arbors, and oscillating laps, but these are not necessary for beginners.
8. Four Stage Tumbling Process
How do you complete the four-stage rock tumbling process? Let’s delve into each stage:
Stage 1 – Shaping
Use coarse grit to remove rough edges and shape your rocks. Fill the barrel about half to two-thirds full, ideally with rocks of various sizes. Add plastic pellets if needed, especially for fragile or flat rocks. Add about two tablespoons of coarse grit per pound of rock, followed by water to nearly the top edge of the rocks. Secure the barrel and clean any spills.
Weigh the barrel before starting the machine to ensure it’s within the tumbler’s maximum weight limit. Tumblers can be noisy, so set up in a garage, basement, or shed with electricity.
Check the progress after a few days to ensure the edges are being knocked down. After a week, when the rocks are shaped as desired, remove and rinse them in clean water.
The time may vary depending on the rocks. Harder rocks with sharp angles take longer to shape than softer, smoother rocks. If needed, continue tumbling, checking daily.
Clean the barrel with soap and water to prepare for stage two, ensuring all coarse grit is removed. Some use separate sponges for each grit type.
Never dispose of waste products (slurry) down the drain!
Stage 2 – Medium/Fine Grit
Follow the same process, adding pellets if needed. Clean the pellets thoroughly, or use a new batch. This stage should take about the same time as stage one.
The goal is to remove visible scratches/cracks/pits and create a dull glow on the dry rocks. Check progress daily.
Stage 3 – Pre-Polish
The purpose is to make rocks silky smooth and bring out a bit of luster. This stage also takes about a week.
Stage 4 – Polish
Use a grit that looks like a fine powder. After a week, your rocks should have a bright shine.
Protect your rocks by using plastic pellets during this stage.
Burnishing
Burnishing is an optional fifth stage that enhances brightness, particularly for agates and jaspers.
Instead of grit, use soap or powdered laundry detergent to add shine and remove haze.
Test if burnishing will help by buffing one side of a rock with a soft cloth. If the buffed side is shinier, proceed with burnishing. Use borax or shaved ivory soap without additives, and add plastic pellets.
Use the same ratios as in the grit stages: about two tablespoons per pound of rock. Only 24 hours in a rotary tumbler is needed, but longer is better.
Consider batching similar rock types during the polish and burnish stages, especially with quartz.
Completing the entire process takes about 3-6 weeks. Remember, patience is key!
9. Common Questions
Let’s address some common questions about rock tumbling.
Can my rock tumbler be used for other things like shells, glass, or coins?
Yes, with some adjustments.
Shells
You can tumble seashells, but skip the coarse grit stage. Shells are fragile, so fill the barrel as much as possible with filler. A vibratory tumbler may be better for polishing shells.
Glass
You can make your own sea glass. Use glass at least ¼” thick, like stained glass or landscaping glass. Be delicate and reduce time in each stage, especially stages one and two. Use plenty of filler.
Coins
Clean stained coins in a tumbler, but never clean valuable coins, as it destroys their collector value. Use aquarium gravel and dish soap instead of grit, and limit tumbling to a few hours.
What magazines and online forums do you recommend?
- Magazines: Check out publications focused on geology and lapidary arts.
- Online Forums: The Rock Tumbling Hobby Forum is a great place to connect with fellow enthusiasts.
What are some good media (or grit) substitutes?
Some substitutes include:
- Ceramic pellets
- Aquarium gravel
- Marbles
- Sand
- Walnut shells
- Corn cob
- Stainless steel bb’s
- Tile spacers
- Crushed glass
For beginners, stick to the standard grit levels recommended by your tumbler’s manufacturer.
Where to buy roughs?
Buy roughs at local hobby or rock shops for expert advice. Alternatively, purchase them online from places like amazon.com or therockshed.com.
How to maintain tumbler?
Follow the instructions in your tumbler’s manual. General rules include:
- Keeping the barrel clean.
- Lubricating bearings every 30 days.
- Ensuring proper drive belt tension.
Proper maintenance extends the life of your rock tumbler.
How much grit to use?
The amount depends on the tumbler, brand, size, stage, and rocks. A general guideline for a 3lb rotary tumbler is 2-4 tablespoons of coarse and medium grit and 4-6 tablespoons of polish grit.
Buy a basic four-stage grit kit on Amazon.
How much rock to use?
Use about 2lbs of rock for a 3lb barrel. The remaining space is for grit, filler, and water.
How loud is a tumbler?
Tumblers can be loud, especially inexpensive models. Keep your tumbler in a separate room like a basement or garage.
Where to buy rock tumbling supplies?
Purchase supplies from amazon.com, rocktumbler.com, or therockshed.com.
What is rock tumbling grit made of?
Rock tumbler grit is commonly made of silicon carbide (coarse and medium grit) and aluminum oxide (pre-polish and polish grits).
How to polish rocks by hand without a tumbler?
Hand polish soft rocks using wet/dry sandpaper and a soft polishing cloth like felt or leather.
Which rock tumbler is best?
The best rock tumbler depends on your needs and experience. Lortone and Thumler’s are generally favored brands.
10. Final Thoughts
Rock tumbling is a rewarding hobby for all ages. Whether you’re crafting jewelry or spending quality time with family, consider trying it out. At rockscapes.net, we encourage you to explore the world of rock tumbling.
Ready to start your rock tumbling adventure? Visit rockscapes.net today to discover inspiration, detailed guides, and expert advice for creating stunning landscapes with stone. Contact us at Address: 1151 S Forest Ave, Tempe, AZ 85281, United States. Phone: +1 (480) 965-9011. Start creating your dream landscape now!
