Vibratory Cleaning of Brass Cartridge Cases, Wet Process Instructions using 4mm Angle-Cut Cylindrical Ceramic Media
If black powder was used as a propellant, the cases should be rinsed under running water first to remove most of the loose deposits. If possible, de-prime the cases at the range and place them into a wide-mouth plastic jug half-filled with water and a squirt or two of dishwashing detergent. At home, use a garden hose to rinse the cases in this same container, all the while gently agitating them. When the rinse water runs clear, drain and place the cases into the tumbler bowl along with the media charge and liquid burnishing compound.
Step 2: Place cases, media, and liquid burnishing compound in the vibratory tumbler.
The 8 pounds of very hard, fine-grain, low-porosity 4mm diameter by 5mm long angle-cut cylinder white ceramic burnishing media charge that comes in the kit should serve for the majority of the common sizes of vibratory tumblers used for cartridge case polishing. Larger volume tumblers will require a correspondingly larger media charge. Some of the less expensive vibratory tumblers will not have sufficient horsepower to move the heavier mass of the ceramic media load. For best results, the tumbler bowl should be at least 75% full. Rotary drum tumblers will also work, but you will have to experiment to find the correct amount of media. Use just enough liquid burnishing compound to keep the ceramic media wet as it gently rolls over and cycles around the vibratory tumbler bowl. Using an excessive amount liquid of compound will not make the cases come out any cleaner or shine any more, but will result in excess sudsing, and may overflow outside of the vibratory bowl. A 6-qt. capacity Thumler’s Ultra-Vibe 18 tumbler requires less than 1 qt. of liquid compound, and does not require the use of a cover during the cleaning cycle.
Note on Burnishing Compound: The kit includes 2 1/4 pounds of Strat-O-Sheen
Burnishing Compound. This equates to
10 dry and level ˝ cup measuring cups worth, and will make up 10 gallons of
case burnishing compound. It is a yellowish
soap powder concentrate, p/n 339-017/5, from Rio Grande Supply, a jewellerly
making supply outfit in
About 2 to 4 hours of un-attended running time is usually sufficient, although slightly longer cycle times will not harm the brass cases. Cycle time will depend somewhat on the amplitude force applied by the individual vibratory tumbler. Some vibratory tumblers are more “aggressive” than others, due to motor speed, horsepower, offset shaft weight, suspension dampening design, etc. When the vibratory tumbler is in operation with ceramic, the media and brass will be doing a relatively slow and gentle rotation around the tumbler bowl, not the familiar quick rolling action of the lighter weight corncob or walnut shell media generally used for dry-cycle case polishing. I recommend the use of an appliance timer to control the total amount of process time per batch.
I use a Rio Grande Supply 16” diameter separating screen with 3/8” hole spacing and mating poly bucket to separate the media from the cleaned brass, but any good screening system will work. In any case, treat the cases gently, especially if you do not size them between firings, to avoid damaged case mouths. After separation, the brass is carefully placed back into the same plastic jug used at the range, and immersion-rinsed with the garden hose until the rinse water runs clear. Drain the rinse water and spread the cases out on an old cotton bath towel to air-dry. To avoid water spotting on the dried cases, gently hand roll them over the 100% cotton bath towel to remove any external drops of water, and then move them down to a dry section of towel for final air drying. Here in AZ., we can just leave them outside in the sun for a few hours. The used media charge in the bucket must then be well rinsed. The Rio Grande Supply screening system screens fit down into the bucket, making for easy rinse water decanting. A little wetness left over in the rinsed media charge is not a problem as long as the media is clean. I store the rinsed media in the separator bucket with the screen on top as a lid until next needed.
4mm D x 5mm L - angle-cut cylinder media: NOT RECOMMENDED FOR USE IN BOTTLENECK, OR UNDER .40 CALIBER, CASES
Jim Betush, 07/14/04