Zinc Plating at Home Over the weekend I tried a zinc plating process for small parts at home that was entirely a do-it-yourself exercise. By that I mean that I did not buy any plating kit or anything elaborate for the process. I read about the process on the Honda 305
forum
and based on photos publised by the author and having a bunch of crummy looking parts on my Scrambler, I thought I'd give it a try.
I'm sharing this here because I think everyone on this forum who is interested in sprucing up their old bike should know how to do this. This topic may have been covered on this forum before so I don't want to rehash old news. I'll just give you a quick rundown of what is needed and provide a picture of parts I plated over the weekend. I will be using the process when I get into the resto of my '66 Bonnie.
Materials
Zinc - I used pure zinc roof strips sold to prevent fungus on roofing
Vinegar
Epsom Salts - 100gm/liter
Sugar - 120
gm/liter
Small 12vdc power supply (3 volts minimum)
plastic pail
digitial multimeter or DMM (for measuring milliamps)
small variable resistor (potentiometer or pot) - 500 ohms Radio Shack
Brass wire brush
Digital timer - not absolutely required, but makes things easier.
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 and the end of that wire becomes the positive terminal for the set up.
String another copper wire across the top of the pail that is electrically isolated from the cathodes. That wire is the negative terminal and the wire from which you will hand the parts to be plated. We'll call this the top wire.
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. 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.
Connect the negative lead of the charger to the negative terminal of the set up (Top wire) . Connect the positive lead of the charger to one terminal of the potentiometer. Connect the positive lead of the DMM to the other terminal on the pot. Connect the negative lead of the DMM to the positive terminal of the set up (cathode wire). Set the DMM to milliamps or amps as your meter requires.
Look at the rating on your charger. It should give the output voltage and the output current. It may give the voltage and watts instead. If it gives watts, just divide the watts by the output voltage to get the output current in milliamps. That output current is your max current. If you exceed that, you will damage your charger.
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.
Plating
With everything connected and the part in the bath plug in your charger. Adjust the pot so that the current in ma is at or below the max output current for your charger.
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, 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 axel in the attached photo would not fit thru the wheel bearing when it was done so I polished the plating from the shaft section. The OEM plating was only on the ends of the axel as well.
Attached is a photo of some 305 Scrambler parts I plated over the weekend. This was the first time I've ever done this, having read about the process on the 305 forum on Friday. Here's a link to that thread so you can read the other details I observed as I did this.
http://www.honda305.com/forums/viewtopic.php?t=6584
I've also attached a photo of my set up. My pail is a 1/2 gallon pail that had hot tube chemicals in it before. Try your local diner for similar plastic containers. They get tons of them and normally toss them out. Don't use a huge 5 gal pail because proximity of the part to the cathodes determines the time required to get a good plated surface. Also note that the plating is line of sight. By that I mean the zinc ions travel from the cathode to the anode (part) in a straight line. So if you have only one cathode, the surface facing it will plate better than the surface not facing it. This is why I say to surround the outer wall of your pail with zinc cathodes all hooked in series. This also means that for parts like the axel spacers and that big axel nut in the photo, I had to make a small cathode to fit inside the ID of those parts and not touch. I made a smaller set up with a small plastic butter tub to plate the ID on those parts first, and then did the outer surfaces in the set up shown in the photo here.
You won't be disappointed with the results. Happy Plating!
regards,
Rob
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