Voltages for Brush Electroplating

A. Donald,

First welcome to the world of brush plating. The answers to your questions are as follows:

1. I am confused as to what you mean by brush, we use anodes of various sizes wrapped with cotton or some type of sleeve (Pellon, Dacron, Wool, etc.). The wrapping serves two purposes: first, it holds the solution while plating; and second, it acts as a barrier between the anode and the work piece.

2. The voltage for Gold plating should be kept low between 3-6 volts, if the Gold deposit starts to look dark simply turn down the voltage. The amperage rating will range from 1-3 amps depending on the size of the area you are plating and your voltage setting. On very small parts you may not even notice the amp meter moving.

3. With just plating small components you can use a small machine at 15 volts and 15 amps. You must also take into account the voltage and amperage required for the activators and any preplates that are needed; on small parts this size machine will work.

Thank you for the prompt and precise reply. It is greatly appreciated. As to your question about brush plating, some companies supply an electroplating kit that contains an actual brush with bristles. The handle is metal with horse-hair type bristles that is connected to the positive terminal of the power supply. They just used a brush instead of an anode covered with a dacron sleeve. Would assume the dacron sleeve would give better results. Anyway,thanks again for answering my questions.

Don Roberts

"THE" brush plating book:
Electrochemical Metallizing by Marv Rubinstein

on AbeBooks

or eBay or

Amazon

(affil links)

A. Don,

I work in an electroplating shop. We used to do gold and silver plating, but have been out of the business for awhile. I electroplate cadmium in a large bath, but I also do stylus cad.

I agree with David Crocker, I have never heard of horse hair bristle brushes. First of all you must come in close enough of contact with a part to create uniform, even plating. The only way I know of that works well with any plating is the anode covered with a cotton insulator.

You can use platinum, stainless steel, and carbon rods as your "brush" I would recommend a variable 15 volt rectifier rated at 20 amps max output. You will adjust the voltage for plating. The current (amps) will follow with the correct amps. In other words, you will plate by voltage, not amps. Your surface area, in square feet, will determine your amps.

As David said, your appearance of the plating will determine your voltage. If it has dull luster, increase the voltage. If you have the voltage too high, you will develop nodules of the metal you are plating within your cotton insulator, and the plating will be pitted or burnt. Arcing will occur eventually.

Hope I have given you some helpful advice.

A. Fine horse hair brush is used to apply gold foil on objects. Richard

Hi Richard. You're right of course! Perhaps the people offering brush electroplating kits with horsehair brushes got a bit confused about what they were trying to offer :-)

Regards,

A. Hi Don. It is possible to do electroplating with small batteries; our FAQ on How Electroplating Works instructs schoolchildren to use one penlight battery for their science projects in electroplating. But the heart of the issue is Faraday's Law of Electrolysis, which says: How much metal you move from the anode to the cathode is exactly proportional to how many electrons you move from the anode to the cathode, i.e., the current you apply multiplied by the time you apply it for. That's just how electroplating works, and there's little you can do about it.

So, if you have a couple of small batteries, you can only plate slowly (because of their limited current), and you can only plate a very thin layer on a very small part before the batteries are exhausted. If you are plating pin-head size parts, milliamps will be sufficient; if you are plating parts of a few square inches, 3 amps or more will be required.

As you know, electroplating requires DC current, because it is the movement of electrons from anode to cathode through the power supply and its wiring that drives the electroplating -- by oxidizing (removing electrons from) the metal of the anode thus causing it to dissolve as positively charged ions into solution, and supplying electrons at the cathode, which reduces those positively charged ions back to metal.

The least expensive power supplies just convert AC current to hump-backed waves of DC current with the voltage oscillating from zero to maximum (high ripple), while more expensive power supplies filter the DC current to a smoother more consistent DC voltage (low ripple) for faster plating and less chance of unwanted side effects from the variable voltage.

Like in other areas of life, there is no limit to how much you can spend; the question is what can you get away with, and at what point is corner-cutting anti-productive. For a hobby-only application, 500 ma is probably okay. Good luck.

Regards,

A. Hi Paul. Your friend is probably confusing you: current and voltage are not the same thing :-)

Voltage is like water pressure. If you live on the fortieth floor of an apartment building, four hundred feet in the air, the water pump supplying you must have offer enough pressure to overcome that 400 foot of water head to keep pushing the water up. Current, measured in Amps, is like the flow rate of water. A fireman's hose delivers far more water in a minute than your garden hose can.

Your power supply requires enough voltage to make the plating occur, and enough current that you can plate the surface of your parts at a practical speed and a speed at which satisfactory plating will occur. Larger, more expensive power supplies may offer higher voltage for specific needs, and/or higher current for faster plating or handling larger parts, and/or lower ripple for more reliable plating, and/or automation features like slowly ramping the voltage up. If the plating you intend to do is small and easy, there's a good chance you can do it with inexpensive hardware.

As we've said on other threads, you can teach a school child to play a piano in 5 minutes or to electroplate in 5 minutes. But being able to plink out Twinkle Twinkle Little Star doesn't mean they can enthrall an audience with their rendition of Rhapsody in Blue. Gold plating of jewelry and nickel plated car emblems is very easy, whereas trying to copper-nickel-chrome plate an old diecasting is a major challenge to platers with decades of experience. If you only want to gold plate very easy things, you probably don't need exotic equipment.

Luck & Regards,

Thanks for your reply. I like your music references but keeping in mind I know nothing about this subject I still don't know if a model train regulator would work? I live in a part of Scotland that is remote and not many jobs (so I have very little cash), so I was looking at trying gold plating to make some cash. I don't intend to do large jobs just things like you mentioned car badges, etc. Sorry if I am being stupid on this subject or missing the point, but to give it a go I need to try it on a very small budget -- hence the question about the model train regulator as they are very cheap compared to the gold plating machines.

Hi again, Paul. Sorry, the point was if it's a hobby and a learning experience, a model train transformer is fine. You should be able to do certain very easy jobs with it, while learning from your failures.

But if you are planning to sell a plated product or electroplating service, and you're not willing and able to use professional equipment, and to secure knowledge in a field that you admit that you know nothing about, I think you'd better re-think that plan. Plating is a chemical and electrochemical art and science; and you need to acquire some expertise in the chemistry, electrochemistry, practical requirements, before you sell the product of that expertise. If you don't have enough curiosity to investigate the issues we're talking about of voltage, current, waveform, ripple, so that you understand the effects of the corner-cutting of trying to use a model-train transformer, that's fine as long as it stays a hobby -- hobbies are supposed to be fun, not a burden, and they only need to involve things you enjoy. But you really shouldn't be selling electroplating services at this point. Maybe this time next year :-)

Best of luck.

Regards,

A. Hello Leah. You need a conductive surface to electroplate onto. And seashells are largely porous calcium carbonate, so you almost surely have to lacquer them before applying the conductive coating. Please see thread 23038,"How to do safe silver plating on sea shells".

"Nothing lasts forever but the earth and sky" -- but the longevity of the silver plating will be closely proportional to how thickly you apply it. Good luck.

Regards,

A. Hi Terry. I wouldn't suggest trying real parts until you have accumulated some experience with scrap parts. And gold is quite expensive, so you might want to practice with copper or nickel plating first. You may learn why shops sometimes want people with 10-15 years plating experience :-)

David Crocker has advised 3-6 Volts for gold plating, so you have a shot at plating as a hobby with 3.3 Volts and 5 Volts available. Good luck, have fun.

Regards,