Letter 064

Help a beginner to copper plating

Now if you're game try this.... I did, and it works beautifully. Buy k-77 root killer.. Mix one lb. to one gallon distilled water, bath temp approx.75 degrees. Purchase a paint product from your local dealer of bright copper, metallic spray paint (not the real cheapo). Clean your substrate then spray it good. Allow one hour to dry then plate as usual. Man it comes out salmon pink.

Good luck,

Philip Camp
- Phenix City, AL

It may be against Federal law to use root killer in a way not in accordance with the indications for use as a root killer. Does anyone know what this stuff is, chemically?

Tom Pullizzi platronica.com Falls Township, PA

Commercial consumer products like that rarely tell you exactly what they are, but I'd assume it is basically copper sulphate.

Ted Mooney, P.E. 
finishing.com
Brick, NJ

The composition of K77 root Killer is >99% Copper Sulfate. Here is the Cornell University site for the Material Safety Data Sheet: http://msds.pdc.cornell.edu/msds/msdsdod/a246/m122546.htm#Section2 [Ed. note: that domain name no longer works in 2005].

Robert Sensenstein
- Ottawa, Ontario, Canada

I am a 'classic car 'restorer, and one of my biggest headaches is the quality of commercial electroplating work, It is simply not possible, here in the UK, to find any electroplating shop that is willing to spend the required time, and degree of care and understanding necessary when dealing with unique, irreplaceable auto parts.
I have attempted my own dull nickel plating process,with far better end results than any plating shop has ever produced for me, and I would like to try my own duplex chrome plating. This naturally entails an acid copper system.(I would use nickel as a strike coat) Proprietary solutions are very expensive compared to commercially available forms of copper sulphate crystals, but I have read, in an item on this website, that there is more to a good acid copper solution than simple copper sulphate and sulphuric acid.
Is this important, given that it is only a 'base coat'for a further two coats of nickel, before the chrome?
Apart from this, is 'agricultural'copper sulphate,i.e.weedkiller,too impure to use as the basis for electroplating solution?
Any help is greatly appreciated.
Many thanks,

Michael Holloway
Ancillary part of my business of classic auto restoration - Chesham, Buckinghamshire, England

Those electroplating shops which you claim don't pay enough attention to quality would not even dream of making their processes from root killer, Michael, although they use a thousand times as much as you and thus have the potential for saving a thousand times as much. Plus, as Tom said, it may be illegal :-)

Get a cheap copy of the Metal Finishing Guidebook or the Canning Handbook and you'll have the ammunition to understand the differences between acid copper plating solution and root killer and why they are important. The only purpose of the copper (in this case) is to be soft and buffable; if you are not going to optimize that, and not intending to buff the copper to a mirror shine, you are better off just leaving out the copper plating. Good luck.

Ted Mooney, P.E. 
finishing.com
Brick, NJ

I found this letter while researching copper plating techniques, and I know it's an old thread by now, but it was the first relevant one I saw. In any case, thank you, because it did have the answers to most of my questions.

I do need to say, however, I am a little put off by the attitudes taken by the professionals who have been answering these questions here. Although your first response, Ted, did give a detailed answer to Lapo's question, it ended with and was followed by little more than thinly-veiled dismissal of any inquirers' ability to understand the chemistry behind it and not drink blue vitriol or HCl.

Granted, it is important to warn a complete beginner of the dangers of things like sulfuric acid, but Lapo at the very least showed enough of a grasp of chemistry to understand acids and know how to read MSDS datasheets. And even though Michael Holloway had limited experience with electroplating as well, his knowledge and concern for the importance of the finish on rare car parts is most likely much greater than that of someone who in plating those parts is being paid to repeat the same type of procedures as the last hundred times. It's somewhat similar to why fast food is sloppier and lower quality than its finer restaurant or gourmet counterparts.

And speaking of root killer and MSDS, I did some research and found the datasheet for K-77 Root Killer on the website of the manufacturer, Roebic, here http://www.roebic.com/pdf/K-77RootKillerMSDS.pdf
It is, in fact, >99% pure Copper(II) Sulfate Pentahydrate - the same purity as the LR (low resistivity) grade CuSO4·5H2O that is, according to my further research, commonly used in electroplating applications. Furthermore, I've found nothing anywhere that would indicate that K-77 is any more restricted in legal use than copper sulfate under any other brand, which makes sense - it is no different and includes no other chemicals, and is mostly environmentally safe (disposal via plumbing is ok, dumping in lakes and rivers discouraged but ok in small amounts) except in amounts or concentrations significantly greater than you'll find at Home Depot.

But yes, proprietary solutions do consist of more than copper sulfate and sulfuric acid. they usually also add small (very small) amounts of HCl, because chlorides at 30-100ppm (depending on the rest of the solution) helps brighten the plating. So does the brightener, usually the main or only proprietary component that I've seen in professional solutions. For an example of the chemical composition of a brightener, check out this patent http://www.freepatentsonline.com/3715289.html

So, it might be easier just to but some other company's - in my case anyway, that's where my tinkering with chemistry gives way to my wallet. Expensive, likely. Necessary? The professionals will always tell you yes. It's just my opinion as a casual idiot, but I've seen a few people achieve great results without it.


That's my casual, inexperienced two bits. Likely nobody reads this anyway, but maybe I added something worthwhile.

Kellin Mavis
- Houston, TX, USA

Thanks for your input, Kellin; the techical parts are interesting.

There was no thinly-veiled dismissal of Lapo or anyone else. When someone says they are an "absolute beginner" and want a copper finish on their iron pieces, it's very possible that they may not realize that jobshop plating services are readily available. The fact that you may enjoy experimenting with plating doesn't necessarily mean that Lapo does! We don't know, so I advised him of the option.

Some people love boat maintenance, whereas I'd rather spend the time in a dentist chair. When I ask on boating sites where I can get so-and-so fixed, people think they are doing me a big favor by detailing how I can do it myself, and cannot seem to believe that I don't want to, so it goes both ways :-)

Lapo may not realize the extreme hazard of working with the cyanide copper plating process that I mentioned. Dozens of trained professionals have died working with cyanide plating processes, and a man died right here in my town a few years ago working with cyanide copper plating solution on his kitchen table. We do our best to arm people with the facts by suggesting they buy or borrow from the library an old plating book or two.

This site does not print ad-hominem postings but we sometimes allow one like yours for whatever constructive criticism of the website may be in it. But frankly the results are the same as any other ad hominem posting; it all just becomes very distracting, diluting the technical content of the site. So you had your one shot; we're not going to let the thread degenerate into further ad hominem postings.

Ted Mooney, P.E. 
finishing.com
Brick, NJ

Specifically doing a sixth grade science project and trying to be the good Dad. Do you think a potato battery will generate enough current to copper plate a small brass key. Can I use copper sulfate disolved in white vineger? Amount of copper sulfate to vinegar required? Using a 2 inch piece of copper pipe hammered flat on other wire.

Scott Durham
none - Charleston SC, USA

I haven't tried it, but doubt that a potato battery would suffice. Because the experiment will work with no copper sulphate, any that you add should be to the good; it's not critical. So I'd say add enough to give a medium blue color. Good luck.

Ted Mooney, P.E. 
finishing.com
Brick, NJ

I am a grade nine student trying to perform copper plating with common kitchen product. Mom says nothing to dangerous. My Dad is away, so it's just me and my Mom. We have already used the battery and copper wires in some salt water to see what happens, so I think to take it further would be an interesting project. Every project known to man is already being done. I would love to do something different this year. Thanks to anyone that can help

dalton scott
student - Canada

Our FAQ on How Plating Works gives the details for safe copper plating, Dalton -- you can tell your mom that no chemicals except vinegar are used.

Have you ever decorated easter eggs, and written on the eggs with a white wax crayon to keep that area from absorbing dye? Maybe you can clean up a quarter real well, then write your name with that crayon before copper plating it?

Ted Mooney, P.E.  finishing.com Brick, NJ

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