Cleaning Cartridge Brass

Cleaning cartridge brass is one of those topics in reloading where just about everyone has a different method of doing it, and to an extent they all work, some work better than others, some have different results.

Generally cleaning brass can be broken up into a few different methods: Chemical washing, Wet tumbling, Vibratory cleaning/polishing, and rotary cleaning/polishing. Vibratory process is very similar to rotary cleaning, the major difference is in rotary cleaning the bowl spins (like a cement mixer) whereas in vibratory the bowl vibrates, and usually has a toroid shape in which the vibration causes the media to turn over. Chemical washing can be combined with Wet Tumbling, but generally isn't. Wet tumbling usually is similar to the rotary process except it uses a media that is water friendly.

Chemical washing goes by several names, and uses many different compounds for achieving the same results. Typically, chemical washing involves an acid, a soap, an emulsifier, and occasionally a light abrasive. There are two chemical washing formulas I have used over the years with varied degrees of success, and they are easy to make at home. The first, is what I call the "Matryoshka" as the ingredient list follows a series of russian nesting dolls. The second is a more common solution which is a mix of CLR (calcium lime rust remover) and hot water with a 1gal to 1pt mix ratio.

Matryoshka Formula*

• 1 gal warm water
• 1 cup white vinegar
• 1 tablespoon powdered laundry detergent
• 1 teaspoon table salt

This formula works very well, and I have used it for years for a pre-cleaning solution. The laundry detergent does a great job removing oils and dirt from the casings, the vinegar attacks the lead deposits on the inside of the casings, and the salt breaks up the surface tension of the water and helps things get cleaner faster. Typically, I will let dirty brass sit in this solution for about 5-20 minutes, occasionally stirring it up. Wash the brass with clean water and either set it out in the sun to dry, or use forced air drying.

CLR Formula*

• 1 gal warm water
• 1 pint CLR (Do not substitute for other brands, use CLR brand)

This formula works great as a post-sizing rinse, as it gets off most lanolin case lubes, it also does a good job of shining up the brass.

* Usage Note: Both of these solutions if used for too long will remove enough zinc from the surface of the brass to turn it pink. While this is not implicitly destructive to the brass (you can still use it) who wants to go to the range with pink brass?
 
Wet tumbling, is something of a cross breed between the chemical methods discussed above, and the physical methods discussed later. For those familiar with it, it is essentially the same process used to make rocks shiny in a rock tumbler, add some water, put into a drum, and spin it for hours, days or weeks. In certain circumstances, a chemical solution may be added to improve the speed or the results. 

An interesting variation on wet tumbling is the use of stainless tumbling media. A new company showed up recently selling 5lbs of stainless steel pins just for this purpose http://www.stainlesstumblingmedia.com/ I have not tried them personally, but the pictures look good, and some people on the internet swear by it. I will tell you, this is a tried and true method for cleaning all sorts of work in many industries, everything from jewelry to doorhandles is tumbled in steel pins or shot.

Before delving into the finer points of rotary and vibratory case processing, it seems necessary to draw a distinction between cleaning and polishing, as they are different processes, you can combine them, but that usually takes too long.

Cleaning brass is best done with a more abrasive compound. To take an example from most home users, walnut media is a substantially more aggressive compound than corncob media. However, walnut is a cleaning media, so it will strip off grime, stains and other blemishes on the brass but will never bring it to a high shine.

Polishing is the final process of cleaning, and is best done with small grained corncob with a burnishing compound and a wax. Dillon's turbo polish is a very very good example of this, as it combines both a burnishing compound and a wax. The waxy layer left behind by polishing compounds does a lot to protect the brass and keep it from oxidizing. A good example of a burnishing compound is the common frankford arsenal polish sold by midwayusa. While it works well for polishing up the surface, the lack of wax means the cartridges will tarnish fairly quickly. One trick, when you have older media, that still has polish in it, but isn't coating the cartridges in as much wax as it did, is to add several teaspoons of mineral spirits to the tumbling media before adding brass as it tends to draw the wax out.

Now lets watch some videos. First up is vibratory polishing on a big scale:



Unfortunately I can't find the youtube video that had a rotary deburrer, so I'll have to take some video of mine next time I fire it up.

I hope that sums up pretty well the differences and answers some questions about cleaning, polishing, and the different methods people use to achieve the same results.