that my nearly 4-year-long
grandmother clock project is finally finished, I'm on to the next big project, which is to restore a 1941
Crosley 03CB console radio. My intention
is to do as complete a restoration as possible (or reasonable), including repairing and refinishing the wooden
cabinet, stripping and repainting the metal faceplate parts, and completely disassembling and rebuilding the electronics
chassis. By disassembling and rebuilding the electronic chassis I mean unsoldering and/or unbolting/unriveting
every component and then testing and reinstalling every part. Fortunately, shortly after buying the Crosley radio
($75) from someone who advertised it on Craigslist, a complete electronics chassis appeared on eBay for $20, so
I bought it. Now I have two of everything from which to make a good working model. Some items like the old paper
capacitors will need to be replaced with modern versions. The vacuum tubes have not yet been tested.
While removing some of the hardware that mounts the electrical chassis to the wooden cabinet, I discovered
some of it was copper plated. So were the 10-32 threaded studs that held the speaker to the frame. At first I
figured I would either just remove what plating remained with a wire wheel on the grinder, or maybe paint it a
I said to myself, "Self, why not try re-plating the copper?" After all, I took a couple chemistry courses in college
and remembered electroplating a nickel with copper from a penny. So, I looked up how to do copper electroplating
on the Internet (a resource not available when I restored my first
Crosley 03CB radio back in the 1980s).
The preferred method seems to be using a solution of copper sulfate with a small voltage potential applied between
a copper bar anode (+) and the work piece cathode (-). Electroless plating could be done with a special commercial
solution, but I didn't want to pay the price (about $40) just to plate some hardware nobody but me would ever
notice. Since I didn't have any copper sulfate on hand I decided the third method would get tried first. That
involved creating my own
copper solution by using copper bars for both the anode and the cathode in an acid bath, with an applied voltage
to facilitate a speedy result.
As can be seen in the photo to the left (above), copper did dissolve handily into the solution after about
half an hour at a current of about 100 mA (not a scientifically determined number - it just seemed right).
You can see the bubbles coming off the cathode copper pipe in the photo to the right. White vinegar was used for
the acid. It started out clear and then turned a characteristic blue-green over time. I was quite pleased with
the result, but the pleasure was short lived. I removed the copper pipe from the negative lead and clipped it
onto on of the 10-32 threaded studs and submersed it in the solution. After about 10 minutes with a current again
at 100 mA the stud exhibited some good copper-colored plating, but it wiped off
a rag - bummer. I spent a couple hours testing other current levels but nothing produced a good robust plating
even though all visible oxidation had been removed from the studs and they were wiped with acetone prior to dipping.
Back to the drawing board.
After doing a little more research I found that high iron content steel, which this hardware likely was, did
not accept copper plating well without first plating with something like nickel. It has to to do with the metal's
location on the galvanic chart relative to copper. Not to be deterred, I decided to try the copper sulfate method.
Where to find copper sulfate? It is readily available online from laboratory supply companies, but the shipping
cost would double the total cash outlay. A Google search revealed that the stuff you dump down your drain or toilet
to clear roots out of underground drain field pipes is loaded with copper sulfate pentahydrate - close enough.
Home Depot sells a 16-ounce bottle for $12. Bingo.
dissolved as much of it as I could get to dissolve in a plastic cup (see photo above left) filled with warm water.
It turned a nice blue color. Another thing I learned on the Internet is that using copper sulfate was tricky because
it would tend to plate the metal without any voltage applied - immersion plating. I tried that first just for
kicks and after about only 10 seconds it produced a really nice copper layer on the stud, but it also wiped right
off. What you need to do is connect the cathode to the part before placing it in the solution - hot dipping. With
a voltage that I knew would produce about 100 mA of current (voltage required varies with distance from the
I dipped the stud into the solution. I alternately inserted and removed it every 10 seconds or so until the plating
looked 'about right' in scientific terms. I held my breath and wiped the 10-32 stud with a cloth. Voila! The plating
remained! I dipped it a few more times for good measure and then did the other three. The four 'T' nuts (aka blind
nuts) received the same treatment. It adhered so well that I could use a brass wire brush to shine up the dull
surface finish without burning through anywhere. All eight pieces were dried, wiped with acetone, and sprayed
with a coat of clear acrylic lacquer to preserve the nice, shiny appearance (see photo to the left).
There are a couple other plated brass parts on the electronics chassis that will eventually get the same treatment.
There are shock absorber springs at each corner of the metal chassis as well as the bolts that pass through the
springs and into the copper 'T' nuts that will need electroplating. Who knows what else I'll decide to electroplate
along the way?
Published August 4, 2013