protecting brass jewelry from tarnishing

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on 24 Jun 2012 3:14 PM

The July 2012 Jewelry Artist just arrived.  Love it!
Bill Fretz' article about making a torus top cuff is wonderful.  The finished cuff looks almost like gold.  BUT - brass tarnishes with exposure to air and skin oils.  Copper would also tarnish over time.


I don't like to use lacquer on metal jewelry because it inevitably gets scratched, and the piece tarnishes along the scratch marks.  What other options are available to protect the brass and copper to keep them from tarnishing or turning different colors over time?

Also, Bill's article includes (step 9) putting the brass bracelet section in pickle after annealing.  Every time I pickle brass it becomes copper plated.  is there a different pickling solution for brass which prevents the copper plating?

thanks for your suggestions!

Mary Alexander

Lincroft, NJ

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BogIron wrote
on 24 Jun 2012 6:44 PM

What is brass made from? That's right, it is an alloy of copper and zinc, so your brass is not being plated with copper, it is only that the surface copper is being exposed by the acid of the pickle. When you polish it all that copper should disappear and leave you with a bright brass finish. Now how do you keep that bright brass finish, well you either polish it almost daily like we did in the military or you put a protective finish on it, not to many other options for copper or brass, or for that matter silver. Some folk use Renaissance Wax to protect the surface of the metal. As far as metal turning, oxidization, I kind of have learned to live with it, it is part of the life of these metals and not all the different colors are bad, I rather like them but they can be hard on clothing and skin.

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on 24 Jun 2012 8:08 PM

BogIron,

your answer makes perfect sense.  Thank you.  If I had dug out my copy of my Tim McCreight metalsmithing basics book, I would have known the composition of brass.

How do you polish brass to remove the surface layer of copper?  will tumbling with mixed shot work?  or do I need to go through red rouge and white polishing compound on polishing wheels (don't have one of those units .... I do have the tiny muslin wheels for my foredom, but they don't seem to be as effective.)

Thanks for the recommendation on Renaissance Wax.  I'll give this a try.

Really appreciate your prompt answer!

best regards,

Mary Alexander

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Posts 367
BogIron wrote
on 25 Jun 2012 1:59 PM

I don't really use my tumbler all that much anymore, I just got to the point where by the time I got to the stage where I had done my usual hand finish I way asking myself why should I put my work in a tumbler when it was ready for the polishing lathe? Not that tumblers don't have their place in the studio, they do, but I'm not a production jeweler anymore and when I'm just doing one offs why do I need to tumble that one piece? OK, I guess that now that's all said and done I really like my brass and copper to have a really nice fire patina on most of the metal. I do incorporate some bright metal but since I don't use anything to protect the metal other than a light coating of Johnson's Paste Wax, the kind that is for floors, I just don't worry about keeping the metal from "turning", it is what it is. I like the reds and rich browns, also some greens and blues, that develop on copper and brass and I like texture. Bright, shinny brass is just too much like long ago days in the military for me.

I guess that I had better add a couple of things. Need a polishing lathe, buy a cheap bench grinder from Harbor Freight and remove the grinding wheels, wheel guards and all that gear so that you are down to the basic machine with just the shafts sticking out then buy these https://eclient.ijsinc.com/eshop/default.aspx?ControlName=ItemDisplay&item_id=DBB57DE8-C01C-444B-B526-9C621E6A8B61&category_id=30BD2495-134B-425E-8911-0A4A7463E7A2 , you will need a right handed and a left  handed tapered spindle to hold the buffs. When my ancient polishing lathe died this is what I did and it was sure a lot less expensive than buying a new Baldor motor to replace the old one. Total cost four years ago was around $45.

Another way to just brighten up the brass after being in the pickle is to use a stiff brass brush that you can buy at Harbor Freight for around a dollar and if you are not going to be putting it back in the pickle they  have a package of three stiff steel wire brushes that are inexpensive also that will leave a pretty nice finish, kind of a matte with a multitude of small scratches.

No, don't ask for a picture of my work, I can figure out metal but for the most part computers elude me and it is frowned upon if I beat them with a hammer.

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Posts 28
Ask Richard wrote
on 30 Jun 2012 10:55 PM

Hi Mary,

Possibly you've solved your pickel / copper issue? You didn't mention the type of pickel you're using... e.g., Sparex #2 (sodium bisulphate), sulphuric acid, etc. The copper plating problem you're likely having is probably due to an electrochemical action caused by iron getting in the pickel. The copper is coming from the brass.

A problem jewelry makers sometimes encounter is having work come out of the pickle, copper colored (plated). Almost always the problem is due to the pickel having been contaminated by iron. Some work may have gone in the pickel with a little piece of iron binding wire still attached. Even removing iron binding wire before putting work in the pickel may not be good enough. Iron oxides on the wire can be taken up by melted soldering flux on the work. The flux disolves in the pickel, iron particles, or compounds, are released in the pickel and the solution becomes contaminated. Pickel is still water clear looking. Iron tweezers could have been used to pick something out of the pickel. Iron, or steel, dust from a bench operation may get into the solder flux then into the pickel. Only takes a few seconds to contaminate pickel which then must be safely discarded. Clean the pickel pot well before mixing up a new batch. Some steel tweezers are 'acid safe.' Stainless binding wire can be used instead of traditional iron binding wire and, depending on the stainless alloy, will not contaminate the pickel. Bottom line: keep irop out of your pickel. 

Richard

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on 3 Jul 2012 10:48 AM

Ask Richard:
A problem jewelry makers sometimes encounter is having work come out of the pickle, copper colored (plated). Almost always the problem is due to the pickel having been contaminated by iron.

 

Richard,

thank you for your observation about possible contamination from a source of iron.  This is not the case in my situation.  I'm the only one who uses the pickle, and I have copper tongs ready at all times.  True ... my pickle (sparex 2) is old and somewhat blue, but it continues to clean silver and copper, so I continue to use it.

My question focused specifically on using sparex pickle for brass.  The result is 100% consistent - the brass winds up copper plated.  This is why I posted my question.

I've been given two very helpful suggestions on this point. 

First, the chemicals and the brass go through a standard chemical reaction, and trying to use sparex as a pickle will always cause copper plating.  Suggested cure - add 3% hydrogen peroxide to the  pickle and use this as a "super pickle" during the short time that he hydrogen peroxide is active.

Second, using standard polishing materials - muslin buffs and the usual sequence of buffing compounds - will remove the copper plating from the brass.

I have not had time to implement either of these two suggestions, but am very grateful to those who posted info to help me.

Thank you also for your post, because iron contamination in pickle is indeed a frequent cause for copper plating.  (in fact, if the pickle has enough copper in it, this is sometimes deliberately triggered to plate the silver solder after copper has been soldered.  This hides the solder seams.)

best,

Mary

 

 

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Haysteria wrote
on 13 Dec 2012 3:41 AM

If you use a solution of half pickle half hydrogen peroxide, you can set the piece in there and brass will start to bubble and the copper will go away.  It will turn back to brass quite fast.  It is best to agitate the piece a little to activate the bubbling. 

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