Rock tumbling is a popular hobby that uses abrasive materials to smooth and polish rocks. Typically, coarse grit is used for initial grinding, followed by progressively finer grits to achieve a high polish. While various abrasives can be used, walnut shells are an economical and environmentally-friendly option.
Walnut shells have long been valued in rock tumbling. Their soft, rounded edges serve as an effective abrasive while being gentle on the rocks. The shells contain oils that help lubricate the tumbling action and have natural antibacterial properties to prevent discoloration. Though a soft media, walnut shells are quite durable and can withstand the tumbling of even hard, rugged rocks over extended periods. They are an affordable option compared to other tumbling media, making them accessible for hobbyists. And since walnut shells are a renewable, organic product, they are a more sustainable choice.
When using walnut shells for tumbling, the typical recommendation is 1 lb of media for every 3 lbs of rocks. The shells should fully surround and cushion the rocks to allow for smooth, even polishing. For initial coarse grinding, a particle size of 8/12 grit is ideal. This can later be followed by finer 120/220 grit particles for polishing. With the right amounts and grit sizes, walnut shells deliver excellent results. Their soft abrasion prevents scratching while their antibacterial properties maintain the rocks’ natural hues. For an economical, eco-friendly tumbling media that can polish rocks smoothly, walnut shells are an optimal choice.
Why do people use walnut shells for tumbling?
Walnut shells have been used as a polishing media for many years and are still one of the most popular types of media today. They are available from several different sources and are relatively inexpensive.
There is some variation in the quality between brands but there is no one brand that performs better than all others. All walnut shells will produce good results when used properly so it’s not necessary to spend extra money on high-end brands unless you want to for your reasons.
The benefits of walnut shells are:
- The antibacterial properties help prevent discoloration in metal products being polished, which is especially helpful when used with copper and silver.
- It’s widely available at an affordable price.
- The media is relatively coarse, which makes it ideal for removing large amounts of material quickly and efficiently. This also results in a high shine being produced on the rocks.
- No special equipment or supplies are needed to use walnut shells, making them an easy choice for people who don’t want to hassle with complicated instructions or procedures.
- The shells are very durable and will not break down easily. They can be used over and over again without needing to replace them, which reduces the cost of using walnut shell media for tumbling.
Treated vs Untreated
There are two main types of walnut shells available on the market today, each with its benefits and drawbacks. One type is treated to be antibacterial which helps prevent discoloration in metals that may occur during tumbling due to impurities being present within the media.
The other type has not been treated so they can provide more agitation during tumbling, which helps remove stubborn coatings and cleanly polish the rocks being polished.
Untreated shells can also help reduce a greenish-brown residue that is sometimes left on stones during polishing by finer grits of media such as corncobs or red rouge. This coloration can be caused by copper from metal alloys, and can be reduced by using walnut shells as the coarser media will remove this copper residue before it becomes a problem.
Since the treated walnut shell is already antibacterial, there’s no advantage to not treating them for that purpose. They do cost slightly more than untreated shells which mean they may not be the best choice if you’re on a budget.
Because they are antibacterial, the treated media will produce a slightly different color on certain stones such as jasper and agate which can be seen if contrasting colors are present in the rocks being polished. If you’re looking for a more uniform finish with less color variation then untreated shells may be your best bet.
It’s important to keep in mind that the type of shell you choose will have an impact on the final results so it’s important to experiment with both types to see which works best for your needs.
Comparing Walnut Shell Tumbling Media with Plastic Media
In the world of tumbling, the choice of tumbling media is crucial. Walnut shell tumbling media and plastic are two common options, each with their strengths and limitations.
Walnut tumbling media is natural and biodegradable, and it is made from crushed or ground walnut shells. Unlike plastic, walnut shell media is generally cheaper and is also used as a blasting media. The shell grit removes paint and dirt effectively without scratching the base materials like brass, aluminum, and jewelry. In contrast, plastic media is great for cleaning and polishing, but it can leave scratches on delicate surfaces.
Tumbling Media | Cost | Biodegradable | Cleaning Ability | Potential to Scratch |
---|---|---|---|---|
Walnut Shell | Low | Yes | Excellent | Low |
Plastic | High | No | Good | Medium |
Walnut shell polishing media is also beneficial in other applications. For example, ground walnut shell is used in reptile bedding due to its biodegradability and comfort for the animals. On the other hand, plastic media is extensively used in vibratory finishing and in some die-casting applications due to its durability.
Moreover, if you’re an Amazon.com shopper, you’ll notice a broader selection of manufacturers offering walnut shell grit, offering top-notch customer support, and specifying how the media can be used.
Selecting the Right Walnut Shell Tumbling Media
When getting started with rock tumbling, one of the most important choices is which tumbling media to use. Crushed walnut shell is an excellent abrasive option.
Walnut shell comes in different grit sizes. A coarse grit (approx. 320 grit) works well for the initial rough tumbling stage. The coarse particles deburr and remove tarnish from jewelry and other metal items without etching the surface. For the final polishing stages, switch to a fine walnut shell (120/220 grit) for a smooth, glossy finish.
Walnut shell tumbling media can be used in both vibrating and rotary tumblers. The rounded pellets are tough but non-abrasive in character and make an excellent heat conductor.
When buying walnut shell media, you can choose treated or untreated. Treated walnut shell contains an antibacterial agent to prevent discoloration. Untreated walnut provides more agitation for cleaning but may leave more residue. Consider which finish you prefer.
A good rule of thumb is 2 lbs of media for every 1 lb of rocks in a rotary tumbler. For a vibrating tumbler, use 3 lbs of media per pound of rocks. Reduce the amount of walnut shell needed if you are just tumbling lightweight jewelry pieces.
Brands like Rock Shed sell excellent quality, reasonably priced walnut shell suitable for use in rotary and vibrating rock tumblers.
A Detailed Guide: How to Use and Reuse Walnut Shell Tumbling Media
When using walnut shell tumbling media, whether in a barrel for rotary tumbling or in a vibratory tumbler, it’s important to get the final polishing just right. Here’s a detailed guide:
Step 1: Start by filling your tumbler barrel about two-thirds full with the items you wish to polish (like jewelry or brass).
Step 2: Add the walnut shell tumbling media until the barrel is about three-quarters full.
Step 3: Add a polishing compound (amount as per the manufacturer’s instructions) to the barrel.
Step 4: Close the barrel and start the tumbling process. The tumbling media should work its magic over a couple of weeks. The walnut media is extremely durable, reducing the need for frequent replacements.
Reuse Steps:
Step 5: Once done, empty the barrel and separate your polished items from the walnut media. Don’t throw away the used media; it can still be reused.
Step 6: Rinse the used walnut shell grit thoroughly to remove any residual polishing compound or dirt. Allow it to dry completely.
Step 7: Store the cleaned and dried walnut shell tumbling media in an airtight container.
As we bridge the gap between using and reusing, you’ll find that this media provides great cleaning and polishing results without the need for frequent replacements.
Tips and tricks for using walnut shells for tumbling
There are a few things to keep in mind when using walnut shells for tumbling. The most important is that the media must be kept wet at all times or it will start to break down and lose its effectiveness.
If you’re using them in a rotary tumbler, make sure there is enough water present so that the shells are completely covered at all times.
If you’re using them in a vibratory tumbler then the water level should be high enough that it’s just above the top of the rocks being polished, but not so much that they can’t freely tumble within the bowl.
Another important factor is to use only fresh shells as older ones will have broken down and lost their effectiveness. The fresher the better so it’s a good idea to buy them from a store that has high turnover rates or from an online retailer who will frequently restock new shells for sale at affordable prices.
Walnut shells work best when used with rocks that have been cleaned of any impurities before polishing. Any impurities that remain will be trapped within the shell and cause discoloration on the rocks being polished.
When using walnut shells it’s important to remember not to leave them in with your tumbling projects for too long as they may start to break apart from repeated use, which can result in fine particles of media getting into your final product. A good rule of thumb is to limit their use to no more than two weeks at a time, with a break in between using them to allow them to regenerate.
Disposal
After you’re done tumbling your walnuts, you’ll need to dispose of the shells. Here are a few ways to do it:
- Compost them. The shells will break down over time and add some organic matter to your compost pile.
- Put them in your trash can. If you have a garbage disposal, the shells will grind up and disappear down the drain. If not, just toss them in the trash can and they’ll eventually decompose.
- Bury them in your garden. This is a great way to get rid of them and also help fertilize your plants at the same time. Just dig a hole about 12″ deep, bury the shells, and then cover them.
FAQs
How many walnut shells do I need to use in my tumbler?
This will depend on the size of your tumbling project and how much media you want to add. The more rocks being polished, the fewer media needed for each load so if you're just doing a few stones then it may be best to go with the higher end of the quantity range.
Do I need to treat walnut shells before using them in my tumbler?
This depends on your personal preference and what you want to achieve from their use during polishing. If you'd like a more uniform finish then untreated shells will be best, but if you're looking for a media that is antibacterial then treating them with an antibacterial agent is recommended.
How long can I leave walnut shells in my tumbler before they need to be replaced?
It's best to limit their use to no more than two weeks at a time, with a break in between using them to allow them to regenerate. If you notice that they are starting to break apart it's best not to use them any further as the fine particles may get into your final product which can be harmful if ingested by people or animals.
Where should I store my walnut shells while tumbling?
This will depend on the type of tumbler you are using. If you're using a rotary tumbler then it's best to store them in a container that can be submerged in water, such as a bucket or bowl. If you're using a vibratory tumbler then it's best to store them in an airtight container to prevent them from absorbing any moisture.
Are there any health risks associated with using walnut shells for tumbling?
There are no known health risks associated with the use of walnut shells for tumbling, but it's always best to take precautions when handling any type of media. Always wear gloves when handling them and avoid breathing in the dust particles. If you get any on your skin, wash them off with soap and water.
Can I use other types of shells besides walnut shells for tumbling?
Yes, there are a variety of different types of shells that can be used for tumbling. Some of the most popular ones are Coconut Shells: These are smaller than walnut shells and have a smoother edge, making them great for polishing small areas such as cabochons or ring bands. They also work well on organic rocks like petrified wood and fossils.
Final thoughts
Walnut shells have been used as a polishing media for years, and there are two main types on the market today. One type is treated to be antibacterial which helps prevent discoloration in metals that may occur during tumbling due to impurities being present within the media. The other type of walnut shell does not provide this treatment but it has better quality control than its counterpart with fewer broken pieces and more consistent shapes. Choose your preference based upon what you want out of your finished product or if you’re looking for an environmentally friendly way to polish metal items, try using some walnut shells! Try them yourself before buying any so that you can see how they work. You’ll likely find their results impressive enough to use them over and over again.
Ready to tumble stones? Identify them first!
Leave a Reply