Why did my brass darken?

[Jaycee357]

I wet tumbled my 223 brass with Dawn and a little lemi shine. It came out really shiny but has darkened when it dried. This is my first experience wet tumbling and I followed directions found on youtube.

 

[forty_caliber]

Howdy and welcome to THR!

How much lemi-shine did you use? 1/4 tsp is plenty. Also to remove and rinse 3x immediately after tumbling. Don't let it soak.

.40

 

[Blue68f100]

Ultra clean brass will tarnish very quickly without a protective coating. The reason most use a automotive car wash and wax for cleaning. The polymers in the wax protect the brass and aid some in resizing.

If you have a film on the brass aka carbon from the cleaning, you did not use enough soap to keep the dirt in suspension. Normally your pins will be dirty if this is the case.

 

[Demi-human]

Super clean cases tarnish quickly.
Wash and wax car wash keeps them shiny.
It also makes pistol cases a little easier to size.

Drying in an oven will accelerate this process.

 

[labnoti]

Most likely you simply didn't dry it quickly enough. If you let it soak or sit wet it will darken. I suggest a hot water rinse. The hot water heats the brass a bit so the water evaporates more quickly. Roll the brass around in a terry bath towel. The higher humidity you have, the more effort is needed to dry it. It's bone dry where I live so hot water will flash off the brass pretty quickly. If it's more humid where you are, you can use an air compressor or a shop vacuum on blower mode to blow it dry. You could use a hair dryer or a heat gun. You could put it in a pan and stick it in the oven at a low temperature setting. You could lay it out on a mesh screen and leave it in the sun.

Brass has a lot of copper and it will tarnish over time. To prevent tarnish in longer-term storage, keep it in a sealed container with little air or oxygen. I find a ziplock bag with the air squished out of it will keep it tarnish-free for at least a few years and that's all I care about. If you wanted to preserve it for decades you could look into vacuum bagging or nitrogen-flushing, desiccants or activated carbon and so on. I shoot it and clean it again before I have to worry about all that.

I do recommend nickel-plated brass for carry ammo because it generally goes exposed for months if not longer.

 

[tightgroup tiger]

I wet tumbled my 223 brass with Dawn and a little lemi shine. It came out really shiny but has darkened when it dried. This is my first experience wet tumbling and I followed directions found on youtube.

Did you use Stainless Steel pins in your tumbler?

 

[CrankyCraig]

I wet tumbled my 223 brass with Dawn and a little lemi shine. It came out really shiny but has darkened when it dried. This is my first experience wet tumbling and I followed directions found on youtube.

Oxidation. Get some wash n wax it will make a huge difference

 

[edwardware]

You got it too clean, and it oxidized a bit. No harm.

 

[sbwaters]

Instead of Dawn, use a dollop of ArmourAll Wash and Wax

 

[12Bravo20]

Yes the wax, no matter if you use something like Nu-Finish/similar or something like ArmourAll Wash and Wax, helps polish the brass and keeps it from tarnishing. As others have said, it also helps with resizing too.