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Brass Electroplating

09/29/2009 2:31 AM

Hello CR4 members

Not long ago I purchased from net some kind of dedicated brass electroplating chems.

They concisted of two different white powders that mixed with water made a clear mildly acidic smell electrolyte to use with brass anode and 1-3 Volt at temp normal to 50 deg C. The results I have are amazing far better than my expectations but then concerns come to mind.

How safe are they?. And don't send me to the seller. I had difficulty to communicate about price and basic specs. Can a genious out there give a clue on the subject? Are we talking about cyanides? I'm taking every precaution possible but how about breathing the stuff ? And if cyanide type how poisonous is it ? Know I took some chances. Don't beat me on that.

Appreciate any help

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#1

Re: Brass electroplating

09/29/2009 4:20 AM

It is not possible to comment here very much without knowing the metal that is to be plated onto the brass anode. That will give a hint as to what the powders are comprised of, which then would enable their respective Materials Safety Data Sheets to be looked up on the internet, which would then bring the safety information up in words of one syllable.

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#2
In reply to #1

Re: Brass electroplating

09/29/2009 9:55 AM

Thanks for your responce. Brass is the plated film too so presumably the chem is a mix of Cu and Zn salts and because I see some dissolvement of my brass anode after some time assume there is some balancing there. I have tested on steel, iron and Zinc with superb results. I think the key to identify them is their form before diluting: white powders mixed at 1:1 ratio or is there any simple test to detect -CN-

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#3
In reply to #2

Re: Brass electroplating

09/29/2009 11:22 AM

The plating on the brass cannot be a mixture of metals, as one metal will plate in preference to the other due to their differing electrode potentials, which is a characteristic of the metal ions.

The item to be plated has to be connected to the cathode, as this is where the dissolved metal ions from the powders will plate-out. The anode, being brass which is not particularly corrosion-resistant, will be dissolved by the negative ions in the solution as part of the process and become part of the spent solution.

The most common plating solutions of these metals is their sulphates. However, copper sulphate has a strong blue colour when in aqueous solution, which hasn't been mentioned in the postings so far as an observational comment. Many sulphates are readily soluble in water (calcium and magnesium being two that aren't) as are many cyanides; gold cyanide is soluble, for example.

There would be little point in zinc-plating onto zinc, so it is unlikely that zinc salts will be in the powders given that plating onto zinc has rendered "superb results".

The composition of those powders needs to be established before safety-related information can be located. Cyanide ions if present, though toxic in themselves if ingested, inhaled in aerosols and possibly by skin contact, are not a hazard if proper handling and disposal precautions are followed, which can be found on the Material Safety Data Sheets [MSDSs]. If the composition of the powders cannot be established, try a Google search for the MSDSs for some of the plating metals' sulphates and cyanides. Handling precautions might be similar. If the exact composition of the powders remains unknown, default to the the most stringent safety information and the strictest disposal regulations for the spent solutions across the MSDSs selected.

Pay particular attention to the disposal advice on the MSDSs. Tipping spent solutions down the drain regardless of these and causing a violent process disturbance at the local sewage treatment works by so doing will not make one very popular there....

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#4
In reply to #3

Re: Brass electroplating

09/29/2009 12:08 PM

Propubly my poor English is to blame for not being very comprehensable. Sorry.

This plating I'm refering is not a single metal e.g Cu or Zn electroplating. You use brass (Cu-Zn) alloy for anode and you get brass (Cu- Zn) alloy covering the plated object, the cathode, not only Cu ,not only Zn. Not sure how this is accomplished electrochemically but it works. To give you a clue slight change in electrode colors can be noticed by varying the voltage meaning the potencials you refere do have impact on the process, If the anode gets redish means more Zn is diluted than its percentage in the anode alloy and same time cathode gets little more whitish (gets more Zn than supposed analogy). I try to keep same color on anode and cathode by varying current and all is fine. Suppose this balance is dependent on temperature and other factors. By the way I found a process supposed to detect CN: treatment with iron sulfate and then sulfuric acid should give detectible prussian blue (hope)

What if positive?

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#5
In reply to #4

Re: Brass electroplating

09/29/2009 10:42 PM

If you refer to the table of electromotive potentials you will see that copper and zinc are not at the same voltage. That means if you operate a reversible cell at an equilibrium (low current) you will plate only one metal until that is gone and the voltage goes up and then the next one. If you operate at a higher current and depart from reversibility you will find two or more metals will plate. The higher the current, the wider the range you can span, but the lower is the quality of the plating. Above a certain current metals will precipitate as a sludge and well as some will plate.

http://en.wikipedia.org/wiki/Standard_electrode_potential_%28data_page%29

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#6
In reply to #5

Re: Brass electroplating

09/29/2009 11:35 PM

Got the picture. Expanding this logic you could use two different anodes one Cu and one Zn with separatly adjusted currents to cathode (resulting to different absolute voltages for each) and could regulate upto a point the Zn to Cu ratio of the resulting brass. Looks smart I'll try it. But my safety concerns about the damn solution still stands and I'll keep precautions for the worst case scenario as PWSlack suggested untill I figure out it's contents

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#7
In reply to #6

Re: Brass electroplating

09/29/2009 11:57 PM

Cu-Zn Alloy Metallization through Reduction-

Diffusion Method Using Ionic Liquid Bath at Medium-

Low Temperatures

Kozo YANASE, Kuniaki MURASE, Takashi ICHII,

and Hiroyuki SUGIMURA

Department of Materials Science and Engineering,

Kyoto University, Kyoto 606-8501, Japan

(Cu-Zn alloy)

is of importance for decorative purpose, the use of cyanide

baths makes the working conditions of electro-platers

worse

http://ecsmeet6.peerx-press.org/ms_files/ecsmeet6/2009/04/23/00002721/00/2721_0_art_1_k9lbgg.pdf

most comprehensive and regularly updated mineralogy database

http://www.mindat.org/chemsearch.php?inc=Cu,Zn,

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#26
In reply to #3

Re: Brass electroplating

02/13/2015 12:02 PM

This is simply not true - alloys are successfully plated commerically all the time and brass is routinely plated.

It is slighly irksome to read faulty "scientific" reasoning quoted as fact which flies in the face of what any industry professional would contradict with solid evidence in the form of a plated part - thats why I feel motivated to reply five years after the posting because I hate to see disinformation like this posted.

I wish those with a little knowledge of electropotentials would stop extrapolating this as unfounded "fact" on the internet when as they write brass is being sucessfully plated 24/7 around the world - it is possible to plate alloys period indeed alloy plating is becoming more and more prevelent as engineers increasingly demand plates with different physical characteristics.

It is true that in one metal in an alloy will often show a preference to plate out before another and combating this tendency often involves additional agents to suppress one metal so as to even out the balance - getting a particular ratio (brass/copper) and surface colour quality is not always easy - thats the platers art - but it is possible.

Just look up commercial brass plating which is mainly cyanide, there are kits for home platers which use a non-cyanide process and many claims are made for good quality finishes.

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#8

Re: Brass Electroplating

09/30/2009 2:54 AM

I am guessing, but I am fairly sure that you are not in the USA, or Germany as you would have to get by law full details supplied with the chemicals. Probably in most European countries.....

In the USA, for some years now, the old metal preparations have been banned for at least 8 (maybe more) years due to Cyanide and other dangerous chemicals. Much equipment is now built with Zinced steel to prevent rust, but looks nowhere near as good as the old Brass (looking) finishes we used before....

I find the chemicals that you have very suspect and you should be most careful with what you do with them when they are used up.......in Germany, the costs of disposing would be extremely high, far higher than their original cost!!!! Disposing of them illegally could result in fines that might go into the Millions of €€€€€€€!!! I am NOT kidding.......

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#10
In reply to #8

Re: Brass Electroplating

09/30/2009 6:10 AM

Sodium thiosulphate is well known as a cyanide killer for lab disposal of cyanide as well as an antodote for cyanide poisoning.

Most labs where cyanide is routinely used know this and are prepared with disposal instructions and injection kits.

It can also be destroyed in the lab with hypochlorite, as long as you keep the Ph below 10.5 to avoid HCN generation.

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#11
In reply to #10

Re: Brass Electroplating

09/30/2009 7:17 AM

I assume you mean pH above 10.5.

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#9

Re: Brass Electroplating

09/30/2009 3:17 AM

The traditional brass plating electrolytes are cyanide based. Cyanide is commonly used in plating. Since the deposit on the cathode is 70/30 brass, ideally a similar anode helps maintain ion concentration.

However, cyanide free baths are also now available. Plating voltages and current densities may vary.

http://www.caswellplating.com/kits/brass.htm

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#12

Re: Brass Electroplating

09/30/2009 12:08 PM

As others have mentioned, you would have a hard time getting this in the US without there being an MSDS (Material Safety Data Sheet) for it. (Although products sold in consumer sized containers don't require MSDS's)

The risks could be high. I'd have it analyzed at a university. Here, if it were found that the material contains cyanide (and the company fails to make you fully aware of that) the company would probably be sued out of existence.

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#13

Re: Brass Electroplating

09/30/2009 1:13 PM

How difficult and expensive is it to plate Nickel with a layer of Brass.

I have Nickel plated steel Ball bearings, that I would like to make look like gold.

I have checked into just buying them, but there are incredibly expensive.


Thanks

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#14
In reply to #13

Re: Brass Electroplating

09/30/2009 2:02 PM

You need "Knacker Lacquer". It adds lustre to your cluster!!!

If you have a son afterwards, you can name him "Terminator"..or the "Tin Man" if you are over 60!!.

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#15
In reply to #13

Re: Brass Electroplating

09/30/2009 9:10 PM

I knew a plater whom refused to acknowledge precautions when plating Nickel. Within eight months she was dead and the cause was; yeah you guessed it.

The monetary expense is small but adequate ventilation may prohibit unless done in open air though even then exhaust ducting would benefit you.

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#16
In reply to #15

Re: Brass Electroplating

10/01/2009 8:57 AM

Found some kind of old responce from seller in my spambox "...for this item not more carefull. it safty. you not worry it. fo..." and I used to think my English was bad. Thanks for the shock bwire but not intend to die any time soon so won't count too much in his/her reassurements will still be carefull and of course check possibility of false alarm.

Anyway I tried plating with two different anodes Cu and Zn. Exactly as I suspected. You can control plated brass color (Cu/Zn ratio) varying the two currents. Only setting Zn current too low makes Zn anode go dark gold possibly gets Cu from solution(?) I increased it immediately and all back to normal after some time. Cu anode has no such problem always clean. Can't believe the variations and surface levelness I get with this method. Just not yet know its rust resistance on iron alloys .Thanks to all guys

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#17
In reply to #16

Re: Brass Electroplating

10/03/2009 4:01 AM

Would it be possible to get a link to where you bought these powders? am interested in trying it myself.

Thanks Garth.

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#18
In reply to #16

Re: Brass Electroplating

10/04/2009 2:25 AM

Cu +2 ion to Copper metal is +.34 volts

Zn+2 ion to Zinc metal is -.76 volts

It's not going to work that way...First plate Copper, second Zinc onto Copper then heat to bring out the Brass

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#19
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Re: Brass Electroplating

10/04/2009 9:31 PM


Some experimental results. Top left is my Cu anode. Down Zn anode and some useless stuff at various currents. Now about source google liquidbrass+ebay and don't blame me for anything

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#20
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Re: Brass Electroplating

10/05/2009 6:32 PM

It looks quite effective.

How does it stand up to an abrasion test?

It is usual to put a pure copper base on steel before plating with other metals, the way you are doing it should work OK for this.

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#21
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Re: Brass Electroplating

10/05/2009 7:01 PM

It is very common for plating operations to first coat with copper, aluminium is also used in this way but copper is preferred for high grade finishes.

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#22
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Re: Brass Electroplating

10/05/2009 7:27 PM

Plate with aluminum? Plate onto aluminum?

Both are exceedingly hard to do with water based methods.

Please explain...

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#23
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Re: Brass Electroplating

10/05/2009 10:17 PM

To plate on aluminium or stainless it takes one more preparing bath phase, zincating. Look it up. Electroplating Al never heard such a thing. Do you mean anodizing?

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#25
In reply to #22

Re: Brass Electroplating

10/06/2009 1:10 AM

Cheaply Chromed items often have AL electroplating to steel as the base then chrome. Chrome loses it's appeal when applied directly to steel. Plating first with Copper then nickel then chrome is a good way but isn't classified as cheap.

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#24
In reply to #20

Re: Brass Electroplating

10/05/2009 10:55 PM

Missed your Q before. Hey it's brass supposed to be relatively soft gold-like decorative finish (also supposed low friction and rust resisting material). If you mean adhesion to base metal I think It's as good as it gets. No way to strip without hurting base metal. Anyway think increasing Zn makes harder more yellow brass. Up right big object in photo is very low Zn and yellow car key down right much more. Use it on car few days no prob

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