Crushed walnut shell is used as a brass cartridge cleaner and polishing media by many re-loaders. Walnut shell media is great for cleaning really dirty or heavily tarnished brass from either spending a lot of time on the ground or being fired multiple times without proper cleaning.
What is Walnut Shell Polishing Media?
Walnut shell polishing media is walnut shell crushed or ground to a specified particle size. The particle size is designed for cleaning cartridge cases in a rotary or vibratory tumbler for reloading. Walnut shell media is an environmentally friendly product that can be reused.
Treated and Untreated Walnut Shell
Crushed walnut shell can be purchased untreated or treated. Untreated walnut shell is used in brass tumblers to remove thick residue and heavy tarnish from shell cartridges that are going to be reloaded. Much of the time when reloaders use untreated walnut shell it is only to clean of the heavy tarnish. After it has been cleaned with the walnut shell they will use treated corn cob media to get that final polish on the brass.
Treated walnut shell media is the same product as untreated except a polishing compound has been added to the media by the manufacturer. Using treated walnut shell polishing media will save time in brass preparation, because not only does the walnut shell clean the residue and tarnish off the brass it also polishes the brass in the same step because it has a polishing compound mixed into the media.
When purchasing treated walnut shell it is a good idea to find out what polish the media has been treated with. The media can be treated with the manufacturer's proprietary brass polish or a common powder brass polish such as red rouge.
Some powder polishes will leave a color tint to your brass which may not be desirable. For example red rouge polish will leave a reddish tint on your polished brass if the media was overloaded with the polish. If a liquid polish is used in the media there is generally no color residue left on the cleaned brass.
Alternative Walnut Shell Materials
Ground walnut shell reptile bedding sold at pet stores is sometimes use as a brass polish by people who are concerned about price. However, this reptile bedding has much larger particles than walnut shell media that has been crushed down to a smaller more effective size for brass polishing. The larger particle size can still clean your brass although it will take longer to get the job done and may get caught in necked casings requiring you to manually remove the media.
Walnut Shell Media in Vibratory and a Rotary Tumblers
Walnut shell media is primarily used in a vibratory tumblers. The rapid vibrations of a vibratory tumbler greatly increases the cleaning and polishing effectiveness of the crushed walnut shells on the brass cartridges. This vibrating action also increases the cleaning action of the walnut media on the inside of the casing and in the primer pockets.
Walnut media can also be used in a rotary tumbler, however it doesn't seem to be as effective on the interior of the casing as a vibratory tumbler. If you are using a rotary tumbler and need the inside of the casings to be as clean as the outside then we suggest using stainless steel pin media that is designed for cleaning brass in a rotary tumbler.
How Much Media to Use
Many tumbler instruction booklets come with recommendations for brass polishing. If yours does not, below are some general guidelines to help guide you.
In a vibratory brass polisher, filling the bowl about two-thirds full with walnut shell media is common practice. Then fill the rest of the bowl with casings. Once the tumbler is running you will be able to add more casings to the bowl. Add them slowly making sure that you do not add to many. If you have more shells then media it will take much longer to clean your cases as they are not going to be completely surrounded by media through the entire run. Also your casings may end up scratching each other if they are continuously rubbing against each other.
In a rotary tumbler the barrel should be filled half full with walnut media. After the media is in add casings until the barrel is at about 75% capacity. If you over fill the barrel there will not be adequate tumbling action in the barrel and your cartridges will not get cleaned and polished.
These are starting points for how much media to use. As you do more and more case polishing you may find a more suitable ratio of media to casings that works more efficiently or quicker in your specific tumbler.
How Long Does Walnut Shell Media Last?
The useful life span of walnut shell cleaning media varies depending on how much it is used. New fresh media cleans brass rapidly. As it is used it becomes rounded, dirty and clogged, increasing the amount of time required to clean the brass.
When the time to clean and polish a batch of shell casing increases to about twice as long as the first run with that media, it is a good time to replace your media.
If the cases are still being cleaned in an acceptable amount of time but your not getting that nice polish that is desired itís time to recharge your media. To recharge the media replace one-quarter to one-third of your media with new media and add fresh polish. Add the polish to the media and let the tumbler run for five or ten minutes, before adding casings, to allow the polish to spread throughout all of the media.
This is a picture of Thumler's treated black walnut shell media for brass cartridge cleaning.
This video shows how to use, and how well, walnut shell media works in a rotary tumbler.
In this image you can see the results of polishing brass in a rotary tumbler with walnut shell media.