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Brass become dark in magnetic polisher


my brass pieces become dark when i put them to polish in the
magnetic tumbler. And I have to invariably scrub them with a brass
brush to get the shine back. can anyone explain why…the silver
pieces on the contrary come out shining



I have had interest in this occurring as the solution get old or
putting different metals in the magnetic tumbler. An old friend on
orchid John Burgess from New Zealand posted that the problem of dark
pins and items coming out black might have to do with the PH of the
solution. He suggested Coke as an additive since it has phosphoric
acid would clean all…It did! Since then I have experimented with
vinegar, pickling, silver dip solution,and the results were that it
seems necessary to do this from time to time to not get reverse
plating from pins on to the Items. I think that brass may need a
solution of a different PH than what you are using. So you may want
to experiment.

Good Luck Ron


Hi, I recently have found that my silver pieces are coming out of
the tumbler all black as if oxidized completely. Using the brush to
reshine them is a lot of work for me. Why is this happening. I have
changed the water and soap solution a no. of times. Should I buy
some new steel shot as the shot itself seems oxidized too?

Sheryl from Vancouver


In place of the Coke products- You will not have as much of a mess
with the sugars and other solution additives if you use OSPHO
concrete cleaner- it is a standardized solution of phosphoric acid
that has no additives- easy to mix and at 4.50/gal in my neck of the
woods- its cheaper than coke! It can be found at most Tru-Value or
Ace type hardwear stores- or Agriculture supply houses.

This is as well the same solution I acid electro-etch with and it
works like a champ for that as well (Search orchid archives for
Kahiko’s tutorial on this).

From VA- be safe and have a great day!


Sheryl - Try cleaning your stainless with a can of regular, not diet,
coke - let it go flat or heat it to make the bubbles leave. Just run
the tumbler for 30 minutes or so. This darkening often happens when
you haven’t been using either: enough or the right soap for steel.
The requirement is quite straightforward, but when ignored, yields
exactly the results you have observed.

Judy Hoch


Judy - why regular and not diet? The acid seems the same. I just
used Diet Coke as an electrolyte for electro-etching and it worked.
Not as well as a strong pickle, but it worked.