How to Keep Reloading Brass from Tarnishing

  • Written By Eric Crouch on February 11, 2020
    Last Updated: February 4, 2021

Reloading is an economical and personal art. Not only can you save lots of money by reloading your own ammunition, but you also get to customize the ballistic qualities of your rounds and really bring out the best in your personal rifle build.

Yet even experienced reloaders forget about the potential dangers and hazards of allowing their brass casings to tarnish. The fact of the matter is that any reloader in it for the long haul will need to learn how to prevent their brass casings from tarnishing in the first place, as well as strategies to eliminate tarnish that does accumulate.

Let’s go over the best strategies and tips to stop your brass from tarnishing over the short and long-term.

Why Does Brass Tarnish?

First things first: brass is an alloy made of copper and zinc. It’s traditionally used for bullet casings because it affords both exceptional strength and shaping qualities without being so rigid as to cause it to explode or fragment when it expands during firing. In other words, brass casings are tough but they also have enough inherent flexibility to let them expand as they emerge from a rifle. This, in turn, allows them to be reused so long as they are properly cared for and reshaped.

However, brass can oxidize over time. In normal cases, many brass materials are produced and sealed in a particular way to prevent the copper alloy from coming into contact with oxygen. But even in the best-case scenario, brass casings will eventually wear down and the copper alloy will become exposed to the air. This results in oxidization.

Oxidization isn’t a problem by itself. Most people think of tarnishing as a result when oxidation causes a marring of the brass surface, which prevents the material from looking clean or shiny. If it was only an aesthetic problem, keeping your brass from tarnishing wouldn’t be so much of a big deal. 

But that’s not all it does. Because brass contains a significant amount of zinc, it’s also susceptible to a process called dezincification. Basically, zinc erodes over time which compromises the structural integrity of the brass alloy. The copper is able to retain its shape but it’s not nearly as strong as it was before.

Does Brass Tarnish Matter for Reloading?

As you might imagine, this is a big problem for bullet cartridges and cases. Flimsy or fragile cases are liable to explode or fragment when they are fired from a rifle or pistol. This can damage the weapon or the user in particularly catastrophic ways.

As a result, you absolutely must prevent your reloading brass from tarnishing over time. It’s not just a matter of having a collection of shiny brass casings to enjoy. It’s a matter of using your firearm properly and protecting yourself from a potentially harmful or lethal malfunction.

How to Tell if Your Brass is Corroded or Oxidized

Some brass casings might be too far gone for you to recover them for future use. These are known as corroded, whereas oxidized brass can still be recovered.

Corroded brass is really easy to see, however. Just look for red or pink splotches on the surface of your brass casings. This clear discoloration is a surefire sign that you should remove those cartridges and dispose of them in a proper receptacle.

On the other hand, oxidized brass looks nothing like corroded brass. This brass is typically a green or bluish hue with a blackish tint. This oxidized surface will harden over time and become crust like over the surface of the brass material. It can be flaked off to reveal the true brass surface beneath and it doesn’t affect the integrity of the copper in the same way that dezincification does.

Ways to Prevent Reloading Brass from Tarnishing

Thankfully, there are lots of ways you can prevent your reloading brass from tarnishing for clear away tarnish that has already accrued. Many of the same techniques that work for jewelry or other brass materials like copper pipes will work with reloading brass cases.

Clean and Polish

First and foremost, the most reliable way to prevent your brass casings from tarnishing is to clean and polish them every so often. Of course, this can be a big ordeal if you have lots of brass casings to protect over time. We’ll get to more high-capacity methods later.

The good news is that most brass can be cleaned with any kind of abrasive material, like soap or toothpaste. These materials are excellent for rubbing across the surface of any tarnish brass or brass that hasn’t yet acquired any tarnish hue.

You can use a dedicated toothbrush, sponge or polishing cloth. You have an advantage over cleaning off tarnish compared to jewelry because you don’t particularly care what the brass casings look like: just that they are clean and shiny. It doesn’t matter if you use an abrasive cloth that ends up scratching the surface of the brass in minor ways.

Still, it’s not a bad idea to have a specialized brass polishing cloth. Some brass polishing cloths come with a protective wax or other materials to stop the cloth from denting or damaging the brass casings.

Vibratory Dry Media Tumbler

This is one of the most popular brass cleaning methods in the entire world. This is basically just a plastic tub that sits on top of an electric motor, which causes the tub to vibrate. You can place large quantities of brass inside the tub, which will then shake with my new vibrations. It’s a good idea to place this vibratory tumbler in a place far from your workshop or anywhere you’d like to relax; they usually make quite a racket.

The tub is filled with a polishing material like walnut shells or ground corncob. The dry polishing materials, or polishing media, is placed in the tub first with the brass second. Then you turn the motor on and walk away for a few hours until the brass looks clean and shiny.

What happened was the small vibrations caused the dry media to rub against the brass surface and get rid of the sediment on top of the brass.

You can then pour the contents of that tub into a sieve or sifter; this allows you to quickly separate the brass from the dry media. If done correctly, you should have a huge tub full of clean brass ready to go. The good thing about this method is that you can clean lots of brass casings at once without spending too much money or personal time.

However, keep in mind that you need to replace the dry media every once in a while. You also need to clean the tub after every time you use it.

Ultrasonic Cleaners

This next method is somewhat similar to vibratory media tumblers. The ultrasonic cleaner uses a liquid media with a vibrating motor. The vibrations, in this method, happen at close to the microscopic level instead of being something you can visibly see were you to watch the brass be cleaned. It’s almost like dishwashing, and it’s much closer to fully cleaning the brass than it is just scraping away accrued tarnish.

Ultrasonic cleaners are advantageous because they clean the interior of brass cases much more thoroughly and consistently. These can come in a wide variety of sizes, allowing you to pick out larger tubs and motors for bigger quantities of brass. You’ll also need to purchase more cleaning solution every now and again, and mix it with water yourself; the ratio for this is typically 40 to 1.

One other plus side for an ultrasonic cleaner is that dumping out the dirty water is a lot easier and faster than sifting the dry media husks apart from the brass.

Stainless Steel Pin/Liquid Media Rotary Tumblers

Often just called rotary tumblers, these devices use hollow drums that are laid on their sides. They are powered by electrical rollers, which turn the drums. The drums are also filled with stainless steel pins and a liquid cleaning solution; the pins are particularly small to do an excellent job of cleaning your brass case surfaces to a very precise degree.

Other than that, it works really similar to the dry tumbler method we mentioned above. The brass casings go into the drum, you turn the motor on, and the vibrations do the rest. It’s pretty easy to clean out the drums by dumping out the liquid solution, although you have to be careful not to get rid of your stainless steel pins unless you want to purchase new ones.

You’ll also need to periodically purchase new liquid media. But these are oftentimes affordable compared to ultrasonic cleaners. They come in a wide variety of sizes and capacities.

Stopping Brass From Accruing in the First Place

Since oxidization happens when brass comes into contact with oxygen, preventing your brass from coming into too much contact with air is the best way to prevent tarnish from accruing frequently. There are multiple ways you can prevent your reloading brass from tarnishing.

Buy Ammo That’s Recent

For starters, you should never buy ammo from a box dated over 10 years old. Such brass has definitely been exposed to at least some oxygen even in the best-case scenarios. Always try to go for recent ammunition that stands a high chance of still having a sealed container and no progress toward oxidization.

Furthermore, you should avoid buying brass casings that come in a box or carton that is clearly ripped or which does not have an intact seal. The seal indicates that the brass hasn’t come into contact with fresh air since packaging, but a broken seal indicates the opposite.

Where and How to Store

Overall, the best place to store your ammunition, regardless of caliber or type, is in an airtight and watertight can in a cool dry area. You need to make sure your containers are both airtight and watertight to prevent any oxygen from coming into contact with the brass and to prevent your casings from rusting or corroding over time.

Furthermore, it’s always a good idea to place these ammo canisters in between or around dry packets. This is particularly necessary if you live in a naturally humid environment with moisture in the air no matter what you do. Condensation that forms can also be a problem, and dry packets do a great job of diverting this moisture away from your ammunition.

Regardless, you should never store your brass casings in a hot, overly cold, or wet place if it’s not in a fully sealed canister or container. Hot and wet places are the worst possible spots to protect ammunition, so try to find a cool dry place like a garage or a basement. Anywhere belowground is an excellent bet, and it’s a great place to handle your reloading hobby in general.

You also don’t want to bury your ammunition unless you are sure that your containers are perfectly airtight, containers that aren’t airtight will eventually let some air or dirt through and begin the oxidization process. Not to mention that letting your brass casings become overly dirty is bad in general, anyway.

Replace Ammunition

Even the best-stored ammunition eventually rusts or acquires tarnish over time. You can’t be afraid of replacing your ammunition every now and again.

In keeping with this idea, you should always go through your oldest brass first, even if you reload the majority of your cartridges. Using old brass is a good way to make the most of all your ammunition casings while they still have the structural integrity to be of use.


In the end, the defining feature of the reloader that prevents his brass from tarnishing and the one that is not is attention. Any of these above methods will be great for cleaning your brass or preventing it from tarnishing the first place. The key is keeping your brass quality in mind and taking care to store it properly as soon as you purchase it or recover it from the field.

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