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Author Topic: speeding up the tarnish process  (Read 3675 times)
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faskissimo

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« on: Mar 23, 2007, 09:04PM »

Hey everybody,

I was looking over some old posts about speeding up the patina on raw brass, so I went with John Sandhagen's idea about spraying the bell will a vinegar/water mix.  To keep it from dripping, I would rub the mixture in with a paper towel, so that it didn't streak.  I did this several times, and it cleaned off water spots (leaving the towel light green) and it seemed to be working slowly darkening the brass, but I went overboard with the spraying and on the final application, I left it to sit without wiping it down.  The mixture ended up collecting around the bell bead and it turned that area almost a greyish purple color, and now the whole bell is more mottled than it was before I started the process.

My question is, is it safe to use white vinegar (standard 3 or 4 % acetic acid OR the stronger 7-8% pickling vinegar) straight instead of mixed with water?  The idea of using oven cleaner scares me....
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BGuttman
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« Reply #1 on: Mar 24, 2007, 06:31AM »

When you apply a spray you are putting droplets onto the surface.  Some spots get a droplet, others get nothing.  That's why your bell is so mottled.  The purpose for wiping the surface down is to spread the droplets so that all the surface gets the treatment.

The reason for diluting the vinegar with water is so you can control the tarnishing process better.  The stronger the acid, the faster it will work.  To the point where you won't be able to wipe fast enough to avoid the mottling.

The choice is yours.  Want lots of mottling?  Concentrated acid.  Want a uniform color?  Dilute acid and wiping.  Also, expect the stuff to collect in the crevices (like the bell rim) and make it a little darker.

Mind you, I don't condone what you are doing, but it's your horn.
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Bruce Guttman
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faskissimo

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« Reply #2 on: Mar 24, 2007, 07:05AM »

Mind you, I don't condone what you are doing, but it's your horn.

Is there something that I am missing?  All I'm trying to do is speed up the tarnish process.  From what I've read, the patina/tarnish is the brass reacting with sulphur in the air, and the tarnish acts as a protective layer which leaves the brass in a more stable state. 

If there are precautions I should know about, please let me know.  If the best thing would be to just polish it to a uniform shine and then let time take it's course, I'll do that. 
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BGuttman
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« Reply #3 on: Mar 24, 2007, 07:42AM »

1.  Vinegar (acetic acid) does not have any sulfur in it except as tramp compounds.  You are creating copper oxide and some copper acetate (that's green).

2.  Once you start oxidizing the surface it continues.  Look at bronze statues.  Ever notice that they go from that nice ebonized finish to green? That green is additional oxidations coupled with the carbon dioxide in air to make copper carbonate (also green).

Lacquer and plating are ways to prevent this.  Lacquer prevents the oxygen in air from continuing to attack the trombone.  If you find that the lacquer coating is so thick that it appears to interfere with the response of the trombone, a "sacrificial" coating of something more inert (silver or gold, for example) will slow the reaction.  Gold is not as good a candidate because copper and gold interdiffuse and so the nice gold appearance goes away and the tarnish shows up.  Silver tarnishes, too; but the copper doesn't diffuse through the silver as fast and it can be polished up better.

One option you have is to polish up the bell and then treat it with a nice car wax like Turtle Wax Hard Shell.  The wax acts much like a lacquer, but is much thinner.  It won't protect as long but it will slow down the tarnishing rate.

You could also wax a tarnished bell to keep it from going darker.  That works too.
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Bruce Guttman
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john sandhagen
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« Reply #4 on: Mar 26, 2007, 08:17AM »

Remember that the difference between getting a patina and an acid bath is pretty slim.

An you may not be patina materiel...I'm not.  My horn turns dirty looking, orange here, dull brass there, a few green speck...  A couple of my friends have REALLY cool looking patinas, one on a gold brass bell looks like walnut.  I asked what he did...nothing.

Oxide isn't a great protector, otherwise we'd use it.  There is a black oxide process for brass that I inquired about.  The company said that it was uneven and didn't work well on nickel, so as a whole horn finish it was poor.  Also that it rubbed off.  The protection it afforded was in it's ability to hold protective oils like parkerizing.
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John Sandhagen,
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« Reply #5 on: Mar 26, 2007, 09:14AM »

I used Ivory dish soap on mine. Instant patina!
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Thomas Matta
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faskissimo

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« Reply #6 on: Mar 26, 2007, 05:18PM »

Thanks guys....I'll be sure to keep all this stuff in mind.
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John McKevitt
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« Reply #7 on: Jul 25, 2017, 09:06AM »

Hi,I have been looking g into these patina process's. I understand if you use an ammo IA / sea salt solution,you get a nice Dark brown hue. Are these products going to irritate my lungs. I knew someone E who had a Trombone gold plated by a company not in the music biz. They used arsenic in the process. It made him sick everytime me he played it.
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elmsandr

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« Reply #8 on: Jul 25, 2017, 09:11AM »

For fun, there are lots of patina options..

https://www.sciencecompany.com/Patina-Formulas-for-Brass-Bronze-and-Copper.aspx

Your local environment will also make a big difference.  Mine is boring, so my stuff just gets gradually darker and leaves me with some green hands.  I tried speeding it up with the hard boiled egg once, the response was moderate at best.  I have a couple of ancient bells that have that great black/purple sheen to them, but those were like that when I got them.

Cheers,
Andy
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Andrew Elms
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« Reply #9 on: Jul 25, 2017, 10:25AM »

Hi !

I once used amonia to tarnished my raw-brass bell... Was not cautious enough, the thing juste bit through the metal and the whole bell section ended up with a very dark patina, and broke in little bits the minute after.  :( How to destroy a very nice horn... ! Whatever you use, be careful !
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Le.Tromboniste
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« Reply #10 on: Jul 25, 2017, 10:32AM »

Palmolive dishwashing liquid contains small amounts of Sodium bisulfate, an acid salt you get from partly neutralizing sulfuric acid. It is used as pHdown in swimming pools, but also by jewelers to "pickle"  pieces, that is to say, clean it off from any copper oxides.

It is also used by artisans working with brass and bronze to create a patina.

So, it will clean your horn from surface oxydation AND give it a quick patina. You could buy the salt and dilute it in water, but using the Palmolive is very practical - the thick and soapy texture make it easier to rub against the metal and apply evenly. It's cheap, easy to rinse off and repeat. And if you rub enough during the reaction, you can avoid having a patchy result for the most part. 
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Maximilien Brisson
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« Reply #11 on: Jul 28, 2017, 06:30AM »

I stripped the bell, used some Wright's Brass Polish to get an even shine, and then in the words of Ron Popeil. I

SET IT AND FORGET IT!

I just play it and forget about it. I'm not very acidic, so it takes my bell a long time to darken.

Jerry Walker
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« Reply #12 on: Aug 15, 2017, 09:53PM »

Commercially we use Ebanol, finish is achieved in minutes, most times we then follow up with a lacquer, this means it looks good for sale for a long time,  Well until the lacquer breaks down.

Best option for a uniformed finish for the home diy'er, clean it spotlessly, polish it, then get museum was (renaissance) and rub it all over it, the wax slows the patina down but gives it a more authentic patina in the long run, takes around 4-6 weeks to start getting a good patina happening.

Steve
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Le.Tromboniste
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« Reply #13 on: Aug 16, 2017, 09:21AM »

Best option for a uniformed finish for the home diy'er, clean it spotlessly, polish it, then get museum was (renaissance) and rub it all over it, the wax slows the patina down but gives it a more authentic patina in the long run, takes around 4-6 weeks to start getting a good patina happening.

Some makers literally use car wax
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Maximilien Brisson
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