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Help 93: Zinc Plating

I have been busy rebuilding pre-1961 Bikes. Had a lot of trouble with replacing old rusty fixures. Now I replate (Zinc Plate) nuts, axles, bolts and anything else that I can fit into my bucket (I also have a Tray for axles). Much cheeper then buying these parts new, if I can get them at all! I use nothing caustic. All biodegradable. Take a look at my setup:


Materials required

(1) Zinc - I used pure zinc roof strips sold to prevent fungus on roofing (can be bought at Lowes or Home Depot)

(2) Vinegar

(3) Epsom Salts - 100gm/liter (240 grams equal to 1 cup)

(4) Sugar - 120 gm/liter (201 grams equals 1 cup)

(5) Small 12vdc power supply (3 volts minimum with current and volt gauges)

(6) plastic pail

(7) several thick copper wire or stainless steel wire (to hang parts - important: good Conductive wires, I have used solder wire)

(8) several Wires with meter connectors and aligator clips on ends (to connect from power supply to tin and parts)

Building the System:

You make cathodes from the zinc plate and line the walls of the pail with them. Connect them all together using copper wire or screws. Connect one aligator clip to the cathode (zinc plate) and the positive terminal on the power supply.

String another copper wire across the top of the pail(Top Wire) that is electrically isolated from the cathode. Connect this wire is the negative terminal of the power supply and the wire from which you will hand the parts to be plated. This is called the Anode.

Mix vinegar, Epsom salts and sugar until all is dissolved and fill the pail with the solution. Hang the parts to be plated from the Top wire with either copper or stainless steel wire so the part is fully submerged in the plating bath. Connect the DO NOT LET THE PARTS OR THE HANGER WIRE COME IN CONTACT WITH THE CATHODE!! THIS WILL SHORT OUT YOUR CHARGER. The current flows thru the bath, which is an electrolyte and conducts current via the Epsom Salts you added.

Assure that the negative lead of the power supply is connected to the Top wire (anode). Connect the positive lead is connected to the Cathode. And that the anode and cathode are isolated.

Part Prep:

You need to remove all the old plating and any rust prior to plating. You can bead blast, acid clean, wire brush, sand, whatever you prefer. Remember that the plated finish is only as good as the finish on the base metal being plated. I use Phosphoric Acid to remove any old Cad plating and any rust. Stubborn rust like deep pits gets bead blasted. Then with rubber gloves on to prevent greasy finger prints, degrease the part thoroughly in something like acetone, dry it and then suspend it in the bath.


With everything connected and the part in the bath plug in your charger. Adjust the voltage and current on the power supply so that the current in ma is at or below the max output current for your charger (the higher the Amps, the shorter the time).

Leave the part in the bath for 10 to 30 minutes. Unplug the charger and remove the part. The part should be plated with a dull light gray coating. Brush the plated surface (this is called carding) with the brass brush until the bright zinc plating appears. You can put the part back in the bath for a second coat (and third), which I normally do.

Keep in mind that the plating will add anywhere from 0.0005 to 0.003 inch of plating, depending on how long you plate it. So fitted parts may need to be masked with paint or tape or sanded down when finished.


The hanging wires should be very condutive. The more conductive the better to transfer the voltage to the parts. When you first turn on the power supply the "cleaned" parts will "bubble". This "bubbling" will contine for several minutes. The higher the current, the more "bubbles".and the faster plating. When the "bubbling" stops, the part will look "ratty", and the part is ready to be removed and brushed. During a second run, the same "bubbling" is observed.

Old zinc plating does not have to be removed.

You do not have to plate the entire part. You can submurge in the vinager solution only the portion you want to plate. If it is not in the solution, it will not be plated.

Multiple small parts (nuts, washers, bolts, ETC.) can be hung on the anode if the following rules are followed: Make sure they are not touching the cathode. Make sure they have good contact between the anode , hanging wire, and part. Allow approximate 1/2 inch to 1 inch between part to allow even coating.

Large intricate parts need to be plated individually and placed in different orientation in the solution. Multiple plating may be necessary.

Any Questions? e-mail me.

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