Cases tarnished after ultrasonic cleaning

[Donkey Basher]

As per the title - having had little success with it when I first got it (using a bottle of 'proper' cleaning solution) I'd consigned the Lyman ultrasonic cleaner to the back of the cupboard years ago.

However, I decided I'd try again & after taking delivery of some citric acid set it up this weekend - mixture was 1.5l warm water, a generous squirt of Fairy & half a level teaspoon of citric acid.

Initial impressions, with the water still clear as no powder residue yet dissolved, was that I'd get some nice shiny cases.

However, after the first cycle it was clear that cases were far from clean so whacked them through another cycle, then another, then another before finally the water was black & the powder fouling was no more.

All good on that front but after rinsing in clean water & drying them off the cases looked what can at best be described as 'tarnished' & in some cases discoloured almost as if they did been annealed. They do not look dull or 'etched' as others have posted after using too much citric acid in their solution, just coloured.

Without wanting to 'do a wet tumble using pins' or 'use dry media', I'm wondering whether anyone can make any suggestions as to how to prevent this and/or what might be causing it in the first place?

TIA

 

[mealiejimmy]

Basically you just re-discovered what you found out when you first tried using an ultrasonic cleaner years ago.
If you want properly clean, shiny brass, then an ultrasonic cleaner is not the tool to use
The tarnished look comes from using too much citric acid and having the brass exposed to that acid solution for too long
I wet tumble my brass and for 1.5L of water I use less than a level teaspoon of citric acid crystals. With that strength of solution, I can tumble the brass for up to 24 hours with no tarnishing and they come out cleaner than new, inside, outside and in the primer pockets

Cheers

Bruce

 

[Donkey Basher]

Thanks Bruce - if I read your reply correctly you're using the same 1.5l of water & your "less than a level teaspoon" of citric acid is give or take about the same as my half a level teaspoon... so effectively the same concentration?

Think the next time I am going to try just using the Fairy & not adding the citric acid to see if that makes any difference... watch this space!

Beginning to think it's not going to be too long before cleaner finds its way back to the back of the cupboard again...

 

[C h r i s]

Wet tumbling is the way to go. I use half a teaspoon of citric acid, and 2 tablespoons of this stuff: Armor All Wash and Wax 1Ltr | Wilko (its quite often on offer for £3).

They also stay bright and shiny after, but I do rinse once complete in deionised water to prevent limescale spotting.

As Bruce says, they can come out better than new. However I just run them for 2 hours and they are almost as clean and shiny as new.

 

[TheCornishman]

I use an ultrasonic cleaner myself and have never achieved the shiny shiny finish your chasing

My one is a heated set up. I de-prime and deal with the primer pockets and then 5mins in the bath has the most stubborn brass coming out very clean if not shiny

I then usually dry in the oven but have just discovered there ladyships new air fryer drys brass in record time and at sensible temps

Personally I am not worried about crazy shiny brass though I will concede it’s nice to see and easier to spot any unwanted signs of pressure or deterioration

I’ve been thinking about making a redneck wet tumbler at some point… just to have a crack at it really

 

[Alantoo]

If the brass is in contact with citric acid too long or too warm perhaps…it is much more active above room temperature. You may have removed the zinc on the surface so that it was just darker copper oxide that formed after you rinsed it off. If so it should just rub off with your fingers whilst still wet.

Did you use a soda bicarbonate rinse to kill the acid or is your tap water fairly limey?

I did two batches a few weeks ago and one came out much darker than the other. I came to the conclusion the water was warmer the second time around and that I had also given it another few minutes.

Normally I stand about 25 cases in a honey jar head stamp down. With a below level teaspoon of citric acid and drop or two of washing up liquid, pour in hot water and zap for 4-5 minutes then give a shake and repeat the 4-5 minute zap.

On the ones that came out darker I did a third 5 minute zap and the heated tank water was keeping the temperature higher in the honey jar than the first batch.

Alan

 

[Sharpie]

Without wanting to 'do a wet tumble using pins' or 'use dry media', I'm wondering whether anyone can make any suggestions as to how to prevent this and/or what might be causing it in the first place?

Ultrasonic cleaning cannot make your brass shiny.

All that e.g. citric acid does is etch away at the brass, possibly loosening the gunge as well, and perhaps assisting the surfactants in the Fairy liquid as well. Leaving the brass with a little bit of the zinc etched away, and the pure pink copper left on the surface. Which will then tarnish, quickly.

The acid can be neutralised afterwards by a rinse with e.g. dilute alkali, baking powder etc. but that won't entirely halt the process.

A microscopic coating of e.g. car wax polish or other such things can however.

Dry media, or wet media, tumbling works by mechanical abrasion, and polishing, and can be easily combined with say a wax treatment.

I dry tumble, not being OCD about perfectly clean case interiors. Wet tumbling can give a complete inside and out clean, if that's what you want.

US can also be ineffective if using say ordinary tap water with a lot of dissolved oxygen. Yes it might seem to be fizzing away but much of the energy may be being wasted in just liberating the dissolved gas. When I tried it, I simply collected left over water from boiling in the kettle (this has far less dissolved gas). Otherwise distilled water is recommended, which also should have far less gas in it. Nothing magical about distilled, or de-ionised water, by the time some cases have been run through it it will be just as dirty as tap water would be.

Might also explain why it took several runs before it started working properly, by the end of that maybe the water had been largely de-gasified. Smaller, low powered US machines can also easily be easily overloaded by putting too many cases into them. Fundamentally all they need to work is plain water, plus some surfactant to help suspend the debris. A dual frequency machine can also work better than the basic ones.

 

[splash]

I use wet tumble, ss pins and cap full of car wash and wax.
No acids or crystals

 

[Czhowa]

Gave up with the ultrasonic for cleaning brass. I use it for cleaning mod parts and trigger mechanisms if they get grubby.
Wet pin tumbling works for me. Big glug of fairy, splash of lemon juice and a splash of lemon dishwasher rinse aid.

 

[Klenchblaize]

I’ve received various comments about my ultrasonically cleaned colour case hardened-like brass from people on the firing line and such ranges from surprise to outrage at my apparent poor reloading hygiene.

That the cases are in fact super-clean compared to those subsequently polished in a tumbler full of media and Brasso totally escapes these commentators.

Whatever cleaner you use in an ultrasonic bath do rinse the brass thoroughly before drying.

K

 

[scrumbag]

My process is this:

1) Whilst setting up, dump cases in washing up bowl of hot soapy water - this starts softening the carbon and makes the sonic a bit more effective I find and doesn't really add any time (I also decap first and this seems to help get cleaner primer pockets)
2) Using boiling water to make up solution (I use citric acid and fairy, similar proportions to others, about 1/2 teaspoon and a good squirt)
3) When done, dump into clean, cool water with a drop of dishwasher rinse aid to help prevent tarnish and limescale.
4) Dry somewhere warm. You get more limescale if you let dry slowly somewhere cool like the garage (Again you hear of people putting in the oven or a food dehydrator but this seems a little excessive unless you're in a hurry).

That tends to keep tarnish / smear to a minimum or something I can live with.

If you want really shiny cases, you can use de-ionised water or water from a dehumidifier to rinse but I don't usually bother.

Scrummy

 

[Rory]

Yes, cases do look either paler or 'tarnished' after ultrasonic.
My fix - get some 0000 steel wool, a quick twist, top and bottom of the case, and you're back to lovely shiny brass. None of this '2hrs in a tumbler' stuff needed.
I would just use the wire wool if I wasn't trying to get the internals and primer pockets of the case a clean up.

 

[finnbear270]

The most effective for me when I need it is,