Silver Plating at Home

Search the internet for silver plating and you'll find a lot of information aimed at commercial plating shops. They pretty much universally talk about using a cyanide based electrolyte. Not an option for home plating! I didn't find a single credible site that talked about an easy non-cyanide solution. The problem for the hobbyist is that these guys all use the most energy-efficient method (cyanide), whereas in doing it for a hobby - we just want it to work.

You'll also find a lot of information about immersion plating - usually at sites selling kits. They're expensive and from my reading I gather that the coating thickness they can apply is very thin. Besides, I wanted a "do at will" way of plating and didn't want to have to order kits through the internet.

So... I purchased a maple leaf 1-oz silver coin for use as an anode (at the inflated price of $25, but I didn't buy it for the investment). These coins are .9999 silver and are made by the Royal Canadian Mint.

I first tried plating in a 50-50 solution of vinegar and 3% hydrogen peroxide with a little rock salt dissolved in it (a very small amount). The coin fizzed like crazy and developed a white gel-like coating. That wasn't too promising but I tried it anyway. I hooked a penny to the cathode and let it run. I just got a white sludge in the solution. I gave up on vinegar. Interestingly, the white gel slowly turned purple over time when I fished it out of the vinegar. I'm not quite sure what it is, but I'm letting it dry and will try to figure that one out later. Here's a picture of it:

[Edit: I believe the white "gel" was Silver Chloride and that it turned purple due to exposure to the light. Silver Chloride is used in photographic film. It was generated due to reaction with the silver and the rock salt (sodium Chloride).]

Since acid didn't work, I decided to try a base. I tried just hydrogen peroxide with a few tablespoons of Sodium Carbonate (to make it around ph 11 or so). You make sodium carbonate by "cooking" baking soda for about and hour at 375 degrees C in the oven. Again, the silver fizzed like crazy, but this time a hard black coating appeared (Silver Oxide, I'm guessing) rather than the white gel. That was more promising. I hooked up a shiny copper penny, set the power supply to 9 volts, and let it go. It took a while, but a purple coating started on the penny. It was soft and wiped off easily. I set the power supply lower to about 5 volts and it started to get a little silver on it. I found that by wiping the purple coating off the penny every now and then, and sanding the silver anode, I was able to get a nice shiny silver coating on the penny. It worked.

Here's a picture of the setup. The big "coin" on the red anode (positive end of the power supply) is the silver. The coin on the cathode (white - negative end of the power supply) is a loonie (this was my second plate). You have to be careful with the alligator clip on the anode - if you dip it in the electrolyte it will decompose into the solution, so keep it out.

Power supply settings during plating:

And a picture of a Loonie after plating. As you can see, it's got a nice shiny silver coating. I then went on to plate my brass door key which worked as well, although it was kind of beaten up to start with, so it looks like beaten-up silver.