Re: What's your experience with ultrasonic cleaners?
I posted this in another thread yesterday, but I'll repost here rather than linking to the other post since it's more on topic here.
I disagree with the ultrasonic method being a pain in the ass, but I'm a chemist and my mantra is: all problems can be solved with chemistry. I don't have any real data, but any physical method (media polishing) it seems is going to remove metal from the case. What's more, beating your brass up with hard heavy particles of stainless steel (called shot peening in the metallurgical realm) is going to work-harden it and you'll need to anneal more often.
I use a home-made cleaner that is dirt simple and very effective: take a 1 gallon bottle of distilled water; add 1 tablespoon of powdered citric acid and 1/2 teaspoon powdered sodium lauryl sulfate. Citric acid can be found at big-box home improvement stores like Lowes or Home Depot as a "water softener cleaner" (
Filter-Mate). I've tested "Filter-Mate" and it's 95% pure citric acid.
Sodium lauryl sulfate is a little harder to come by in pure powdered form, but it is just an anionic organo-sulfate surfactant or, in layman's terms: "detergent" so you can use household detergents to the same effect. It's best to use one that doesn't have alkaline softeners like sodium carbonate or sodium tetraborate (borax) as these tend to neutralize the citric acid (laundry detergents and automatic-dishwasher have these). A good eco-friendly liquid dish washing detergent (like clorox "green-works" dish detergent) is probably a good substitute since it won't have perfumes and dyes and is mostly sodium lauryl sulfate (10-15% according to the MSDS); use about a tablespoon of this per gallon.
I run my decapped dirty brass in an ultrasonic cleaner with a heater for 4 or 5 of the longest cycles (480 seconds), rinse with hot tap water, then final rinse with very hot distilled water (the hotter, the quicker they dry). If I'm going to resize the brass, I'll clean it first as above, skipping the distilled rinse, then lube and size and run them through another cycle in the US cleaner to remove the case lube, then rinse as above with distilled water.
They don't come out mirror polished, but they are clean as a whistle and I don't worry about losing any metal or work-hardening my cases.
Before and after shots (actually after/before in the first shot):