Wet Tumbling Brass - Strange Discoloration

Have any of you encountered your brass coming out of a wet tumbler discolored (I tumble with stainless steel pin media)?

I've been wet tumbling my brass for probably 4 years now, and normally the brass comes out looking like new brass. The lot I'm processing right now is Lapua brass for my competition rifle. I normally dry tumble briefly for the sake of keeping my sizing die clean, then size/decap, and throw the brass into the wet tumbler to clean it up nicely before loading.

This time I was tired when I started, and I tumbled wet before sizing. The brass came out perfect, as always. But, I decided to give the brass another run through the wet tumbler after sizing, just to get all of the case lube off. When I pulled the brass out after its second tumble, I noticed that it looked a lot darker than normal in some spots, and had uneven discoloration.

My recipe for this tumbler has always been very warm water, Dawn dish soap, and some Lemishine. I've always had great results in the past.

Any idea what might have gone wrong this time?

 

Tumbling with the case lube is probably the problem. Do the cases feel sticky like they still have some residual lube on them? There was a recent thread about removing case lube not long ago. I think they ended up using a solvent to get it off.

 

Is your water source downstream from an industrial chemical plant? Some chemical from a discharge might have gotten into the water, something the Water Department does not test for.

 

I think it's your lube, still stuck to the cases and dirt has now stuck to the lube. What did you use?

 

lube

 

I wet tumble, polish in the vibrator, size and then repolish to remove the lube. The only time I get the discoloration that you got is when I use too much lemishine.

 

It might be too much lemishine, I suppose. Everything else was the same process, type of water, etc. I’ve done this for years and never had this result... but I eyeballed the lemishine tonight (didn’t use much, but it’s hard to say).

Any idea if that would compromise the integrity of the brass?

 

Did a aluminum case get in the mix? I had that happen and I found a couple aluminum cases figured the lemishine reacted to them??

 

Lemi shine! I had the same issue and cut back on lemi and fixed it.

 

To much lemishime makes my brass dull, a stray steel case in the batch will have an effect too.

 

To much Lemishine for sure. I only get this when I use to much.

 

I also run the tumbler with no brass every now and then using just Dawn and you would be surprised how dirty the water is. Just saying.

 

Every once in a while I'll tumble a batch that comes out dull. There are a few things that I suspect cause this. Too much citric acid can. The amount depends on your water quality and you just have to experiment. I use a 9mm case as a measure. A steel or aluminum case mixed in can cause this. Leaving the brass sitting in the tumbler too long after it shuts off can cause this. That was probably my problem.

In your case I suspect the case lube may be the problem. I usually spray my lubed cases with a degreaser before tumbling.

Its a good idea to tumble stainless media in soapy water before ever using it and every once in a while afterwards.

 

Oh yeah I have gone away from Lemishine all together and just use a dash of Armor All Ultra Shine Wash N Wax.

 

If you got a new batch of pins, they could have oil on them still which would be similar to those above talking about leaving too much lube on the brass.
Run a batch in cold water also - hot water makes mine duller here.
And ofc, the lemi-shine to detergent ratio is a thing.

 

If it's lube, you may have to use a solvent to get it off.

 

Wet tumbling with Lemi-Shine will dull the brass if run for too long. Threw me off too when I accidently left it on for 2 hrs. The more Lemi-Shine in the mix the less you want to run it. I switched to Armorall Wash and Wax. You can run it for hours with no issues. Back off or eliminate Lemi-Shine all together. You can always run a batch with Dawn only and add a capful of Lemi-Shine 30 min before stopping and rinsing.

 

Left it in the lemi-shine & soap mixture too long.

 

I wet tumble to get the lube off, and have never had that problem. Could be the type of lube, though. I use the Royal spray case lube. My wet tumbling recipe is about an ounce of Wash-n-Wax, and small amount of Lemishine, and the hottest water that will come out of my tap. I rinse with cold tap water.