Darkened brass after cleaning

[BadQ]

I have been reloading for over 3 decades, so I'm not new to reloading...

I recently had a batch of 338lm brass that I was processing turn dark after cleaning. The only thing I have changed in the last five years is a new case lube. It is an oil based spray product from rcbs. The first time I used it, it stayed on the cases after the ss pin tumble. My fingers turned black while I was rinsing them off, so back in the tumbler with more soap and more limishine. After a second tumble the oil residue was gone. I put them in a toaster oven on warm with a fan to dry them out. The brass comes out looking like it has been sitting in grass at the range for a couple of years. None of my other brass has ever done this. I can hand polish the darkness off, but that will be rather tedious.

Here is brass with a polished case for reference.


Looking for thoughts before I have to hand polish another load of brass.

 

[Huskydriver]

Does seeing your face in the brass make it more accurate or something?

 

[BadQ]

Does seeing your face in the brass make it more accurate or something?

No, but it helps my OCD

 

[Hundo]

I have been reloading for over 3 decades, so I'm not new to reloading...

I recently had a batch of 338lm brass that I was processing turn dark after cleaning. The only thing I have changed in the last five years is a new case lube. It is an oil based spray product from rcbs. The first time I used it, it stayed on the cases after the ss pin tumble. My fingers turned black while I was rinsing them off, so back in the tumbler with more soap and more limishine. After a second tumble the oil residue was gone. I put them in a toaster oven on warm with a fan to dry them out. The brass comes out looking like it has been sitting in grass at the range for a couple of years. None of my other brass has ever done this. I can hand polish the darkness off, but that will be rather tedious.

Here is brass with a polished case for reference.
View attachment 7136320

Looking for thoughts before I have to hand polish another load of brass.

What are you adding to your water when cleaning? Too much citric acid (Lemi Shine etc.) added to your solution will turn brass dark and erode it over time.

 

[918v]

Something in that lube is reacting with the lemishine. Stop using the lube and/or tumble it off in dry media.

 

[Changed]

The RCBS lube is lanonlin based. It makes a mess when you try to wet tumble it off. If you choose to use it you have two choices. One, rinse the brass in lacquer thinner, or dry tumble in a vibratory tumbler after sizing. Personally, I like to wet tumble ever few firings. But, for the most part, I've gone back to the vibrating tumbler for everything. I use a mix of corn cob and walnut shell. The vibrating tumbler can do nearly everything the wet tumbler can do, and it is less work.

 

[flyright]

I use the home brew of lanolin/alcohol lube to size then I wet tumble with Dawn/sprinkle of lemishine for an hour and it comes out pristine with no residual lube remaining. So, the RCBS must be something different or the too much lemishine remark is correct. I have found that when I oven dry it does tend to darken the brass a bit so that could be part of it. Or, oven drying with some residual lube would probably do it more. My .02...

 

[BadQ]

Thanks gentlemen

I figured it was something in the lube that wasn't coming off in the wash.

 

[Backcountryguy]

Too much Lemishine is very likely, but also too much time on heat will do it as well.

I do my initial wash after de-priming only with SS pins, Dawn, and lemishine...then I resize. I put the brass back in the tumbler for 1 hour to remove the case lube...on this wash I use the Frankford Arsenal cleaning solution. It removes the lanolin, and the brass comes out beautiful.

The frankford arsenal solution isn’t exactly cheap, but it pleases me to see the brass nice and shiny.

No, nice looking brass doesn’t make it perform any better, obviously. But if it makes the owner happy, that’s all that matters in my opinion