Speeding up brass polishing

[njl]

I have 12 brass portholes that the PO neglected pretty badly. Today I worked away with a copper wire brush and some brasso for an hour or so and got one maybe half done. Any tips on speeding up this job?

 

[njl]

I have 12 brass portholes that the PO neglected pretty badly. Today I worked away with a copper wire brush and some brasso for an hour or so and got one maybe half done. Any tips on speeding up this job?

Correction I believe they are bronze, not brass.

 

[Ross]

Vinegar and table salt is a good way to start. It will brighten a penny in seconds.

 

[rgranger]

Get an aluminum pie pan... scrape the bottom so you expose some fresh aluminum (otherwise the surface is actually aluminum oxide) place your bronze in that and add some baking soda (sodium bicarbonate) and a table spoon or two of salt. Fill with some distilled water and let it sit for about an hour. A splash of vinegar will speed it up a bit.

This works really well on silverware also (skip the vinegar for silver).

 

[RichH]

Bronze is a bitch to polish by 'chemical methods', usually needs an abrasive to accelerate the polishing time.

For 'green' bronze: Sand down to bare metal with progressively finer and finer grits, flat sand with at least 1000 grit, then power polish with 'rouge'.
I like the 3M Scotch-Brite rotating sanding 'wheels' .... just chuck-up in a low speed drill. ditto the flat 3M 'face' disc wheels. Then followup with coarse then fine "jewelers rouge' on high speed fabric buffing wheels.

To prevent reoxidation, tarnish. verdigris formation coat with MANY coats of clear urethane (best is 2-part clear urethanes) .... or remove the part and send it out for heavy CLEAR 'powder coating' ... MUST be 'heavy' coated. Any 'pin-hole' or 'thin spot' in the coating will quickly allow the acetates in water / seawater to quickly reform green 'verdigris' under the coating --- totally seal it with 'heavy' coating.
If you want 'brown': apply/rub a mix of olive oil, beeswax, lemon juice, fine pumice and salt .... thats hows its done for 'statuary'.

 

[zeehag]

i love the patina bronze gets-- looks good on an older boat and does not hurt the bronze. polished bronze stays shiney longer with varathane coating it--spray it on. then in a coupla years, when it starts to peel off, looks like garbage. i sail places i dont want to have folks think i am wealthy in monetary ways--i like my patina.

 

[Joe]

I agree with Karin on the patina........ it's like leaving the teak natural. But, hey, I like Rich's boat alot too... It's beautiful.

 

[WayneH]

IIRC, My brother said they use tabasco sauce on the US Navy brone fixtures. He was disgusted that they waste the sauce on other non-edible things. He said it at least made the meals slightly edible.

But that was a loooooong time ago when he was 18 and I was 14. I'm now 28 with 28 years experience.

 

[zeehag]

aquila is sooo pretty-- mine isnt shiny, but is dull and worn looking-but as a solo female owner, i think mine is sfwr for me.. i dont want to attract the wrong crowd in my situation.
but aquila is sooo puuurrrty!!!!

 

[Chris Burti]

For brass or bronze try Oxalic acid and a green 3M pad... it works like a charm...a little Brasso as a follow up if you want a higher polished finish.

As a reducing agent and strong organic acid, it actually counters the oxidation process. Can be found in ZUD and Barkeepers Friend with a mild abrasive and in Kaboom in diluted liquid form inexpensively in the dollar stores.

It also removes rust stains, bleaches teak without damage to the wood fibers and will kill mold and mildew.

 

[CalebD]

Ketchup or Catsup.
Brush it on and leave for 20 minutes, rinse, rub, repeat.
Works great on copper.

 

[rgranger]

Ketchup or Catsup.
Brush it on and leave for 20 minutes, rinse, rub, repeat.
Works great on copper.

Yep, that should work. Catsup is tomato paste in vinegar... and the tomato itself has citric and malic acids... both of which are similar to acetic and oxalic acid (mentioned above). All carboxylic acids work by making the oxidized metal ions water soluble. See diagram....

 

[RichH]

As I stated earlier chemical methods for the removal of the green 'verdigris' (complex copper acetate/carbonate/chloride/oxide) is difficult and will/can also begin to 'attack' the base bronze (copper component of the alloy) while removing the 'green'.

Citric acid (undiluted lemon juice) will have the best (using common 'acids') 'solubility' of these complex 'copper acetates/carbonates/chlorides' --- take absorbent cotton 'fluff', soak with lemon juice (or dilute citric acid) + vinegar, apply to the bronze, cover with saran, etc. and let soak -- will 'dissolve' most of the verdigris. If the part is easily removable, simply cover with lemon juice (+vinegar) for several hours.
Sure you can use other acids to remove the 'verdigris'; however, the 'reaction time' can be quite long vs. the 'verdigris' and they will also attack/extract the base copper in the alloy .... The important thing however is: this will only remove the 'verdigris' and not 'polish' the bronze. If you want to 'polish' the bronze ... you will have to actually polish/burnish it by mechanical means.
FWIW - the 'ancients' burnished their bronze (statues and armor, etc.) by hand using a mixture of beeswax, salt, wine vinegar, lemon juice, and fine pumice .... and rubbed and rubbed and rubbed until 'mirror bright'; then rubbed on a mix of beeswax and salt to help retard the 'tarnish'.

Just like brass and other copper alloys, the BEST and fastest way is to mechanically polish .... high speed sewn-fabric polishing wheels to which is applied "Jewelers Rouge". Jewelers rouge is especially made for polishing 'red' (copper bearing) metals and is obtained in most 'hardware stores' in 'stick' form - apply it to the spinning fabric wheel.
If the bronze is 'pitted' due to a long-term and heavy formation of 'verdigris' you will have to flat sand down into the bronze until you get a FLAT surface ... and BEFORE you begin the polishing/burnishing.
Chemical 'polishing' compounds wont get you to a FLAT surface and may even 'enhance' the pitting in bronze. A pitted/rough bronze surface is prone to enhanced future 'verdigris' formation.

FYI - "Verdigris": http://en.wikipedia.org/wiki/Verdigris

Brass polishing compounds such a Brasso, NeverDull, etc. wont be very effective on BRONZE.

Hope this helps.