Specifying plating on zamak, Q&A, Problems & Solutions

A. Hi Ale.
I don't know what you mean by "picket" -- perhaps it was an erroneous auto-correct?

Which tanks, if any, have filtration? I can think of 3 causes of roughness:
1. There is 'shelf roughness' which is called by unfiltered particles, and it's called by that name because the roughness is usually most evident on horizontal surfaces where it can settle.
2. Burning at any plating stage can cause roughness.
3. Poor pretreatment can leave roughness in place that get plated over.

Perhaps other readers have ideas.

I would suggest Hull Cell tests of each stage. Perhaps a broken or worn out anode bag is causing the roughness? Tell us more. Luck & Regards,


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

A. Zamac is a zinc based die casting alloy, it is not a type of plating. What is your question?

A. Let me try again. Zamac is a zinc alloy used for making parts. It is not a type of plating. Zamac can be plated onto. After cleaning and activating, it is plated with copper. From that point, the copper layer can be plated with nickel, nickel and then chrome, nickel and then gold, or almost any other platable metal. If your requirement is for decorative use as for bicycle or motorcycle brake levers, then copper-nickel-chrome plating would be appropriate. If these brake levers do not require good cosmetic appearance, and you want only corrosion protection, you can coat them with a chromate film.

It would take a large book to describe in detail the process of plating zinc castings. You may be able to get some good help from a message board on a specific question, but will not be possible to start at zero and learn everything you need to know to do plating from here. You should start by getting a good book.

A. Hi Sarah
Zamac is a substrate, something to make things like levers out of, perhaps as an alternative to ADC 6. You plate other metals onto zamac, you don't plate zamac onto other metals.
Luck & Regards,


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

A. Hi Sarah. You will probably find that cyanide copper plating is the best first step. This is followed with acid copper plating, semi-bright nickel plating, bright nickel plating, and finally chrome plating.

We can guide you through the pages and chapters in the right order if you tell us which plating book you got when Jeffrey advised you that you must start with a good book because you'll never get anywhere with just an internet forum.

It disappoints me that people will risk tens of thousands of dollars following the advice of strangers on the internet, but when that advice is to start by spending a few dollars on a book if they can't find it in a library they often instantly dismiss it and forge on :-)

Happy New Year, Sarah.

A. Dear Sarah Mamdouh

First you ask about the suitable zamak alloy for electroplating. It is zamak 4 and it have a especial chemical composition to accept plating process
Second, about the optimum sequence for zamak plating, it is as following

1- soak ( dipping cleaner for zamak)
2- cold rinse
3- cathodic cleaner
4- cold rinse
5- neutralization ( weakly acid, pH = 2-3 )
6- COLD RINSE
7- strike copper cyanide
8- high efficiency copper cyanide or acid copper
9- the watts nickel tank
10 chrome tank finally.

Copper tanks is very important in the sequence of zamak plating because zamak is a zinc-aluminum alloy and the two metals are very active so it will not accept the nickel plating; the nickel solution will damage it.

Thanks

A. Hello. I agree with Mr. Mooney. If you don't read book also, you never understand your questions' answers. Anybody has to answer your detailed questions. I have a very good book that is about plating and finishing. If you want, I can sell it you with available price=?. I can guarantee that the book will improve your plating info.

Sincerely,

Usually available on eBay;

sometimes on
AbeBooks or Amazon

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

A. Hi Carl. For economy, broad coverage, and being tailored to a beginner, I'd choose "Basic Practical Electroplating", a volunteer effort by the Garden State Branch of the AESF. Or, to bring in some topicality and some advertisements to give a flavor of the industry, I'd suggest the Metal Finishing Guidebook ⇨

A. Hi Kenneth. You would need to alkaline copper plate them, then acid copper plate them, then nickel plate them, then either electrophoretically apply a brass colored lacquer or brass plate & spray lacquer them.

These plating processes might not be completely impossible to do at home, but would probably be impractical. You could contract them out though. Considering the difficulties, you might want to try polishing some of the zamac conchos and applying a brass colored wax rub ( ⇦ this on eBay or Amazon [affil links] ) or a brass-tone shiny paint ⇦ this on eBay or Amazon [affil links] to see whether that satisfies you because it would be ten times easier. Good luck.

Regards,

A. Hi Mohan. You have not told us enough about your process and yourself to avoid me jumping to a perhaps erroneous conclusion that you're not implementing chrome plating properly. Zamac is NOT polished to a mirror finish for chrome plating. Sure, you start with a fairly smooth vibratory finished surface, but then you either rely on the self-leveling property of nickel plating to provide the shine or, for "show chrome" you buff after the heavy acid copper plating step. If this reply is confusing you, please see our "Introduction to Chrome Plating".

Luck and Regards,

A. Brass coating for zinc. Take 10 parts saturated ammonium chloride ⇦ this on eBay or Amazon [affil links] solution and 1 part basic copper carbonate ⇦ this on eBay or Amazon [affil links] . Rub it on the object.

Hope it helps and good luck!

A. Hi Mohammad. Zamak is not an ideal material for corrosion resistance; it must be plated (and possibly clear coated) for corrosion resistance. If you are getting corrosion in use, you must improve the finishing. This will probably involve thicker plating.

Something to consider is that the only thing you can reasonably test for is whether the parts meet their specifications. You have to write specifications before you can determine the required testing.

Can you give us a particular: one part and its finishing specification, or its perceived finishing needs, because cost of finishing is also a consideration. As a silly example, heavy gold plating would last nearly forever but is impractical due to cost. Thanks.