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Copper Plating
Copper Sulphate Safety

Copper Sulphate isn't noxiously poisonous - making it reasonalby safe to handle if you're careful, and wash your hands afterwards, however, it is toxic (even deadly, if consumed by the spoonful, so don't do that). Care should be taken to supervise young children when it's around, and keep pets out of the way.

Lifebuilder works in India alongside the poorest Punjabi communities empowering them to improve their social and economic wellbeing.




Electroplating with copper is a classic science experiment that is easy to set up, but loads of fun and can produce highly attractive results - something I haven't tried since my schooldays. I decided to give it a go again.

Materials

copper plating

My materials comprised: A bag of Copper Sulphate crystals (a few quid on eBay), a 9V DC power supply that belonged to some long-dead bit of electronics (a dialup modem, I think), some thick copper wire (stripped out of an offcut of mains wiring cable), an old jam jar and some insulating tape.

I also used a multimeter to determine the polarity of the wires, but there are other ways to do this (read on).


copper plating

I was trying to copper plate the pewter Lard Lamp I made a little while ago. Pewter is mostly tin - and I know tin alloys with copper to make bronze, so I reasoned it should take a copper coating well.

I degreased the object by scrubbing with detergent, then boiling it in dilute vinegar for a minute or two.


copper plating

I bent two pieces of copper wire to fit the jam jar.

The anode (positive terminal) is a loop to fit in the bottom of the jar.

The cathode (negative) is designed to suspend the pewter object and allow the plating bath to circulate all around it.


copper plating

I cut the DC output plug off the end of the power supply cable and used my multimeter to find the negative terminal to attach to the cathode.

Another way to do this is to temporarily attach two plain steel nails to the wires, turn on the power, then dip them briefly in the plating bath - the cathode should identify itself by rapidly acquiring a thin coating of bright pink copper metal.


copper plating

I attached the stripped wires to my copper wire terminals, then taped them into place in the jar

It's really important to make sure they don't touch one another, as this could cause the power supply to blow a fuse (or worse).


copper plating

The plating fluid is made with Copper Sulphate crystals and hot water - adding more and more gradually whilst stirring, until no more will dissolve.


copper plating

I placed the pewter lard lamp on the cathode, topped up with the plating bath solution, double checked that there were no short circuits, then switched on the power.

Almost immediately, the surface of the pewter object changed - turning dull brown pink in most places.


copper plating

I gave it five minutes, then turned off the power and retrieved the item.

There was definitely a good coating of copper on the surface, but it was very rough and dull - this was a bit of a disappointment at first, but then I realised, it probably just needed burnishing and polishing.


copper plating

I'm not sure if it was strictly necessary, but I figured the copper might adhere best to the pewter if I heated it a little with a blowtorch.

(This needs some care in the doing, as the blowtorch flame can quite easily melt pewter, if it's applied more than sparingly)


copper plating

Next, I used a hobby drill with a brass brush wheel to polish the surface.

I wasn't expecting a mirror finish, because the surface of the original pewter object was mostly still that of the natural casting - slightly pebbled from the texture of the plaster mould, but it did start to shine again.


In the end, it's transformed it into quite an attractive object - the copper has blackened in places - presumably because of some galvanic reaction with the pewter, but this gives it a lovely antique effect, with which I am most pleased.

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The wire brush was a fairly soft one made of fine brass wire - it seemed to do a fair job of polishing (it was never going to come up mirror bright, because the underlying metal was straight from casting)
Thanks for the tips on polishing and patinating. I assume the plant food contains salts that are creating the verdigris effect.

Posted by Mike (For Atomic Shrimp) on Jan 26 2011 at 21:20
Wire brush seems a bit harsh for copper, if i need serious polishing of my copper bowls i use a fine "brillo" (wire wool) pad and plenty of water followed by dry wire wool, then a cotton polishing mop on a drill. You might know this already but for nice green patina i use liquid plant food, sends it green in no time!
http://jonpenryn.blogspot.com/2010/11/raven-bowl.html

Posted by jon on Jan 26 2011 at 18:51
It's worth a try, Ken - but it will need to be done on a box made with the sanded side facing out (I think the inside of aluminium drink cans is coated with a thin layer of transparent plastic).
Not sure how well the copper will adhere to aluminium, but it's worth a try...

Anodising might actually be the right approach...

Posted by Mike (For Atomic Shrimp) on Jan 26 2011 at 07:58
What about using this on the aluminum can/embossed box project to make it a copper plated box? Seems like it would be a lovely addition to the box and should even make it tougher.

Posted by Ken Trough on Jan 26 2011 at 00:50
Add a rheostat to the circuit to adjust the current, you get a better finish with a small current.

Posted by Don on Jan 24 2011 at 14:30
I'm definitely going to make this with a lion's head. I'll send you pictures when I do it.

Posted by Philip Dahl on Jan 24 2011 at 13:20
Great presentation. I will definitely try this in the near future. How about other materials - silver, gold, brass, etc?

Posted by Larry on Jan 23 2011 at 19:43
Awesome website. I enjoyed reading all your stuff, keep it up.

Posted by Alex on Jan 23 2011 at 05:56