I am asking for help on a difficulty that has me stumped. Surely others have run into this, but I have never seen it mentioned. I built a rotary tumbler capable of cleaning 10-12 lbs. at a time, using SS pins and the usual mixture of Lemashine, pins, a few drops of Dawn, and water. It works well for a while, but inevitably the cases start acquiring a dull sheen, defeating the whole effort. Rubbing the cases with an old T-shirt or towel uncovers a decent shine, but that's no good. The pin maker was aware of the problem and suggested soaking the pins in a caustic solution, a weak acid, and rinsing them thoroughly before use. I did this, and thoroughly cleaned the polisher drum, which has aluminum tumbler vanes. This lasted a couple runs, but the problem soon returned. My suspicion fell on a chemical reaction between the cases, the vanes, and the Lemashine, but I never solved the problem. Has anyone ever had this  problem, or anything like it, when cleaning cases?

I have a Thumler,s Tumbler that I have used for 5 years and I also use the stainless pins with water and a couple of capfuls of Lyman Turbo Sonic Concentrated Case Cleaning Solution. As I only use BP the cases are first de capped and scrubbed out in water first before putting them in the tumbler.
I give them a coupe of hours and they come out looking like new every time, including the primer pockets.
Just my 2c worth.
Mike.

I also a Thumblers.  BP cases are decapped and soak in water with Dawn until I get around to tumbling them.  I use ceramic media and a capful of stuff I got from a guy at Friendship (G Vest). I used to use Dawn and Lemishine and they would come out clean and shiny, but would turn dull and tarnish. This stuff keeps them shiny.

Too much Lemishine (or any acid) for too long can start to leach the zinc out of your brass, causing a pinkish appearance and weaker brass. I suspect the acidic Lemishine is also reacting with the aluminum.

Thanks for all the help, and any in the future. I have had the pink cases occurring, but it's controllable. My problem was the gray scum on the cases, which occurred with smokeless. I clean my BP cases manually, but my BP is increasing to the point I need to pinpoint the exact cause. Especially since my smokeless cases are free range pick- up but I have to buy my BP cases. First, clean the media. Next, no Lemashine. then, no aluminum. Thanks to all.

Rick, Lemi Shine is essentially nothing but citric acid.
Interesting about ballistol. I use a lot of that.

Lonnie

Cleaning bp cases, you might try a dash of oxyclean and water and prewash and rinse the cases before going in the tumbler. Just a dash of any dishsoap with lemon and a small amount of lemishine, then tumble with the ceremic media. After take the case out of the tumbler rinse them in clear water. Then let them drip dry on a case drying rack

Probably mercury from the fulminate primers amalgamating with the brass, although generally this wasn’t a problem if black powder was used.  Maybe the primers had extra fulminate for reliability.

I thought I’d scored big with a bunch of .32-40 HV cases, back when old&used was all you could get, if you were lucky.  After a couple cases broke in the resizing die and a couple more broke in the chamber on firing, I figured mercuric primers from the crystalline look of the brass at the breaks.

It was easy, at least, to salvage the other components.  I could snap the shells in two with my fingers, like we used to do with string beans out of the garden.  Dump the powder in a cup, punch out the primers and tap the bullets out with a punch and a bench block.

I would imagine “Lemishine” gets its name from the citric acid found in lemons.  It’s too weak an acid to dissolve most metals, but it will form “complexes” with their oxides which are water soluble.  Thus the rust, tarnish and other undesirable coatings on brass and steel goes away without dissolving and weakening the metals themselves.

Unfortunately, in this case, if it wasn’t for the thin coating of aluminum oxide that forms on aluminum exposed to air, protecting the metal underneath, the aluminum would corrode and react with almost anything, including weak acids like citric acid.  I’ve seen aluminum, amalgamated with mercury, grow oxide “feathers” and get too hot to touch, and seen finely divided aluminum catch fire on exposure to air.

You’re removing this coating and dissolving the aluminum as you’re tumbling the cases, with the results you see.  Replace the aluminum vanes with stiff sheet plastic and the problem should go away.