Non-cyanide Copper Plating

A. Hi Amit. Everything must be right at every step for adherent plating, of course. Unfortunately, that means that something wrong at ANY step can result in non-adherent plating :-(

I would suggest scrubbing a few parts with pumice, as well as looking for water break on all of the parts, to assure yourself that the parts are properly clean. Also, plate some steel Hull Cell panels to determine whether the problem is within the plating step itself.
Luck & Regards,


Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

A. I think that alkaline non cyanide copper operates only on steel and not on zinc castings.

A. Ken, I'll have to disagree with the people who indiscriminately knock all non-cyanide copper processes. I have experience with the EPI / Electrochemical Products Inc. [a finishing.com supporting advertiser] E-Brite 20/20, the predecessor of the 30/30 bath. It did all the things the manufacturers claimed and then some - I successfully electroformed with it. The bath operates at a pH of (if memory serves) around 9.5, has great adhesion to steel, nickel, etc. you can plate out of it directly onto aluminum (naturally, no adhesion unless you zincate, but who cares when all you want is to electroform). I know people who use the 30/30 bath and are quite happy with it.

Hope this helps.

Wishing you luck, PlaterB

A. Hi, Kirk. Copper electroforms have been built at least 1/4" thick, maybe more. So the answer is that there is probably no realistic upper thickness limit to copper plating. If you pose the details of your own situation maybe we can surely help further. Good luck!

A. Ted is correct. The question is so broad. When you say non-cyanide, you open the door to several chemistries (sulphate, pyrophosphate, fluoborate). Of those, the one most used to develop thick plates is the sulphate. A practical limit could be how much roughness can be tolerated on the outer surface. Without additives, which tend to increase stress and can lead to cracks, thus limiting thickness, 1/8" can be done with no more roughness than a piece of coarse emery paper. Beyond that, you can go up and end with something that resembles a coral or a sponge.

A. Please tell us what you are trying to do, Kirk.

Can you start with copper pyrophosphate then finish with bright acid copper? Can you buff mid-process to smooth it back up. Do you need 1/4" thick, or is 1/8" enough ... or would you be satisfied to reach 10% of that?

An often-used approach is to nickel plate first, then you can directly plate a simple copper sulphate ⇦ this on eBay or Amazon [affil links] solution very very thick. Is a nickel strike objectionable in your application for any reason?

I guess I'm just saying that I'd prefer if your inquiry could start: "Here's what I am trying to do: ..." :-)

Good luck and thanks for your patience.

A. Apologies, Kirk! Sorry, it isn't our intention to hassle, just to say that the more detail provided, the more helpful the readers are usually able to be.

You may already realize that acid copper cannot be deposited directly onto steel surfaces because it will "immersion deposit" and offer virtually no adhesion (it won't survive brazing). If you can't use a cyanide strike, you would need to try either a pyrophosphate copper strike or a nickel strike.

Then you can finish with an acid copper (sulphate or fluoborate). I don't think .002" is a technological hurdle at all as, when I was involved in the stripping of the copper from the William Penn city hall tower in Philly, we discovered that they had plated copper at least 20 times that thick a hundred years ago.

It should be possible to directly plate .002" of a proprietary pyrophosphate copper in a single step. I don't know enough about it to comment, but Berl Stein has done electroforming with it; you could inquire of a supplier of that process like EPI / Electrochemical Products Inc. [a finishing.com supporting advertiser]. But certainly a nickel strike followed by acid copper would work just fine. Best of luck with it!

A. Hello.

ANALYSIS OF COPPER --

REAGENTS: Ammonium persulphate, concentrated ammonia ⇦ this on eBay or Amazon [affil links] solution, PAN-indicator (1-(2-pyridylazo)-2-naphthol, 1 gr/l ethanol

PROCESS: pipette [pipettes on eBay or Amazon [affil links] 5 ml bath solution into a 250 ml Erlenmeyer beaker, add approx. 25 ml deionised water and 2-3 gr ammonium persulphate. Stir the solution for about 15 min. Add 5 ml of the concentrated ammonia solution; the colour turns to dark blue. Add another 50 ml deionised water and 4-6 drops of the indicator(don't add more. The changing of the colour will be worse). Titrate with 0,1 N E.D.T.A from dark blue to greenish-grey

CALCULATION:Consumption in ml * 1,27 :...gr/l Cu

By the way... How is your bath (performance)? And is it difficult to control? And have contamination problem? And can you plate zamac (zinc die castings)?

Could you answer these questions?

Good luck.

A. The typical acid copper baths (copper sulphate or copper fluoborate) cannot be applied directly to steel because they won't adhere, for reasons more complicated that you probably are interested in hearing in the first round. There are proprietary copper pyrophosphate baths available from several suppliers; these are a bit more finicky than cyanide baths, and I can't guarantee they will discolor with heat in the same way, but they are worth investigating.

Another alternative is to nickel plate first, then acid copper plate. Again, whether this will discolor the same way as their cyanide copper would need to be determined.

A. There are lacquers from companies like Agate that have some fantastic metal-like colors without the evils of plating. Check with them for the level of UV stabilization that the have/need. You might also acquire the book on patinas in the book section at this site. Not that bad priced and lots of pictures. Sort of a minimum library for an artist.

A. I think that when you say dark coating, you are referring to the mill scale on the steel. You can avoid this by buying cold rolled steel rather than hot rolled steel. Alternatively, you can remove the scale by sand blasting, grinding or with a solution of sodium bisulfide and water. You will find this acid salt sold as a pool additive (lowers pH).

A. Hi Akhilesh,
Please clarify if blistering happens between base substrate and alkaline non cyanide Cu or alkaline non cyanide Cu and acid Cu or acid Cu and bright Ni deposit.

Possible cause could be improper activation of base substrate prior electroplating or Cu oxidation prior following plating or poor Ni deposit ductility.

Regards,
David

A. Hi Akhilesh,
You may prolong zinc die-cast activation (or even with electrolytic activation) or plate cyanide Cu strike to improve adhesion.

Also, you may remove organic or metallic impurities from alkaline non cyanide Cu bath to minimize blistering at LCD area upon baking.

Regards,
David

A. Hi Devlin. You might google for "hobby plating supplier" and see if they have a booklet for you or an instruction manual you can buy. But as we've all learned from trying to follow even the simplest step by step assembly instructions for a table or a child's toy, the vocabulary can kill you.

Usually available on eBay;

sometimes on
AbeBooks or Amazon

(affil links)
free pdf is currently available from academia.edu

Electroplating instructions will talk about rectifiers and anodes and cathodes and electrolytes and bus bar and addition agents, and so on, making "step by step" difficult, so it may be best to read a couple of our introductory papers here to learn the lingo. Our "How Plating Works" is for elementary school kids; "Faraday's Law" moves on to high school level; and "Intro to Chrome Plating" addresses practical real-world issues. Spend 20 or 30 minutes on those three and I think you'll be ready to ask step by step questions or consult stuff like the Metal Finishing Guidebook .
without getting quickly lost :-)   Good luck.

Regards,

A. Hi Devlin. You should use copper wire to hang the parts.

Whatever workable copper plating solution you use, I think you will get a plating of good copper metal and that it will patina.

The basic issue is that it isn't possible to electroplate steel from a simple acid copper plating solution because it will have no adhesion (copper is more noble than iron and will deposit on it spontaneously with no electricity, as in the high school chemistry experiment of watching iron nails get covered with copper by simply immersing them in a blue copper sulphate solution), so ...

To usefully electroplate steel with copper you need to either electroplate the steel with nickel first, or you need to use a copper plating solution which complexes (ties up) the copper so it cannot spontaneously deposit. Cyanide copper plating (very dangerous) is the most popular method for industrialists, copper pyrophosphate plating is another industrial method but hard to control without a good lab, and proprietary solutions like the EPI / Electrochemical Products Inc. [a finishing.com supporting advertiser] solutions are another.

I personally don't think electroplating is a great hobby, because it can be dangerous & expensive, the results are likely to be poor, and there is much to be learned before you can generalize (employ what you've learned to somewhat different situations) -- but some people apparently enjoy it as a hobby, especially if limited to a narrow field like plating or electroforming jewelry :-)

Regards,

A. Hi Devlin. When you're using a proprietary like this one, people don't actually know what is in the formulation; you have to follow the technical data sheet from the supplier. I know that's tricky because you're not going to be obeying the letter of the law regarding anode material, etc., and I doubt that EPI / Electrochemical Products Inc. [a finishing.com supporting advertiser] will be periodically analyzing the solution for you ... so you might consider getting a Hull Cell so you can really see what's going on with the bath.

You cannot copper plate over the bluing because the plating must build onto the substrate metal, not onto oxides. I think the best option for hobbyists is to nickel strike first, then acid copper plate.

Regards,

A. Hi Chhavi,
We appended your question to a page where the subject has been discussed with a lot of "ifs, ands, & buts". The usual approach to copper plating on steel is to strike with copper cyanide, copper alkaline non-cyanide, or nickel first -- and then to do the bulk of the copper plating with acid copper plating. But Berl says this thickness is no problem for a proprietary alkaline non-cyanide plating bath, and Berl invariably says something can be done only if he's personally done it.

Regards,

A. Hi Patrick. Absolutely.

But newbies reading this may not recognize some things which you do, like the need for proper pretreatment, and the fact that it is not possible to do alkaline copper plating (or most other platings) directly on aluminum, stainless steel, or titanium.

Regards,

A. Yes it is certainly possible to deposit copper at 250 microns. The most common non-cyanide bath is sulphate based and this can easily produce good deposits up to 1.25 mm thick; after that, it may become a bit nodular and even stressed. You can also use Periodic Reversal pulse plating, which will give even better deposits. Other non-cyanide baths include pyrophosphate and fluoborate; I would avoid the latter as it is very corrosive and toxic, so stick to the simple solutions - copper sulphate based systems.

A. Hi Patrick. Your history is probably right. I was working for M&T Chemicals in the early 1970's, and we were using our pyrophosphate copper in several large printed circuit shops. I was a newbie plating equipment engineer at the time, not involved in the chemistry, but I did know it was our proprietary pyro.

We also did a large copper plating installation for a well-known manufacturer of oil well drilling tools, where we copper plated the steel drill bits for selective carburizing but unfortunately I can't remember whether that was copper pyrophosphate or cyanide copper :-( Luck & Regards,


Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey