What polishing compound for Media

[ColinR]

I clean all my brass in an ultrasound cleaner with water and about 2 tablespoons of citric acid powder to 3 litres. While this gives a very good clean the brass often dries with a light tarnish (and sometimes a pink (copper??) discolouration) which seems to get worse with successive cleanings. I have a vibratory cleaner and new walnut media and plan to give the brass a polish after a few cleans. I used to use walnut and jewellers red paste (rouge) which worked well, but I found a huge can of Brasso and wonder if this is OK to add to the media and if so in what proportion.

[phaedra1106]

Far too much Citric Acid, for 3ltrs all you need is about a teaspoon, all it does is help to soften the water. Ultrasonic tanks just loosen the crud, they don't clean/polish the brass. A vibratory tumbler will polish the cases, adding a drop of car polish or a very small amount of jewellers rouge will help, you can also tear a sheet of kitchen towel into strips and add it to soak up some of the dust.

A change of media may also help, the very fine reptile bedding type works well. Personally if they're really dirty 5 mins in the large ultrasonic tank will clean most of the crud out then 30-60mins in a stailess steel pin wet tumbler gets them looking like new.

[dromia]

Brasso = ammonia so theoretically not a good idea.

I just use whatever is the cheapest car polish of the T-Cut type mixed with white spirit to stop it balling.

Teaspoon of each in my Thumlers rotary tumbler.

[waterford103]

Jewellers rouge available for pence off the bay of e , 1 teaspoon in a vibratory polisher works wel.

[ColinR]

Thanks to all. However, phaedra1106, citric acid has a far more reactive purpose than just softening the water. It works just the same way as putting a penny in Cola and instantly cleans, it also passivates the brass which should have the effect of reducing tarnishing. That said the brass comes out of the tank bright but after washing and drying in the oven at 100 C. it oxidises again. It might be soap (Fairy Liquid) residue from washing before drying although I rinse thoroughly in running hot water first. The brass is certainly clean but visually is a bit off putting as it always looks tarnished. I guess I'll get some jewellers rouge as that always worked well in the tumbler. It would be good if the brass would stay bright as it is after 30 mins in the ultrasound - the appearance just seems to go down hill from there; any suggestions?

Dromia, what is the problem with Ammonia?

Thanks again, Colin

[Mezzer]

I find a bit of T-cut and clean rags supported by a large dash of elbow grease works a treat. Then again, I'm not doing a whole lot of reloading and case preparation at the moment. It's one of those jobs I keep for rainey days when I've nothing better to do.

Mezzer

[dromia]

It degrades the brass, it works on the copper in it.

Ammonia is used extensively in copper removing cleaners.

[phaedra1106]

Passivating brass with citric acid only needs about 1 ounce to 1 gallon of water. After cleaning (if using citric acid) I then neutralise the brass with a final rinse using a teaspoon of bicarbonate of soda in 2l of water. Even when I was using the small (Aldi/Lidl) type ultrasonic tank I'd only put the cases in for 8-10 mins at a time, a good indication for timing is when the primer pockets are clean.

Nowadays I can dump 100 x 308 or 44mag cases in the large tank (only water and a squidge of non-bio washing liquid), give them 5-8 mins then off for a tumble in the stainless stell.

[ColinR]

So I will reduce the amount of citric acid I use to probably a level tablespoon and, something I'd never thought of, neutralise the citric acid in a wash of bicarbonate of soda solution - I have a 25kg bag of the stuff so good to find a use. Then tumble in walnut media with some T cut mix with white spirit. Is it OK to dry at 100C or should this be a bit lower? Presumably 100C is not enough to have any effect on the brass.

One further point; the reason I tend not to tumble after cleaning is media blocking primer holes. It seems to happen with all walnut media for reloading, so is the reptile stuff smaller and won't clog primer holes? If I do do a final tumble I run the cases through the universal deprimer again to ensure there is no media clogging the primer holes, adding yet another process to case preparation.

[rox]

neutralise the citric acid in a wash of bicarbonate of soda solution

How will you know that you have exactly matched the pH and strength of the acid ad the caustic in order to 'neutralise' it? Why replace a self-limiting/passivating solution with something potentially more damaging to the brass? Why not just rinse off the acid?

I use citric acid in stainless cleaning processes (followed by a thorough rinse), and crushed walnut with ammonia-free car polish + white spirit, either for bulk cleaning or final protective polish for longer term storage. From memory the walnut media is 25/50 grit size, which is fine enough not to block flash holes.