Discoloration after Acid copper plating

[neeraj_bapat]

I am plating small pieces of plastic with the help of acid copper plating kit....I am using a current density of 2A/in2...When I take my plated pieces out of the bath and wash them, they turn dark orange/discolored..why is this happening? is it oxidizing? is there any way to prevent it? what should be done after the part gets plated..should it be washed in cold water or hot water??

[ashcroft01]

neeraj_bapat,

It sounds as if you are burning the plate with too high of a current setting.

Are you using 2 amps per square inch? It should be 1 amp per 10 to 16 square inches.

If I have read the post wrong, I apologize.

Copper plate will oxidize very quickly once it comes out of the bath.

Rinse with distilled water and proceed to the next step in plating before the water dries.

If you need to buff and polish first, then dry the part after rinsing, go straight to the buffer, degrease, rinse, pass water break test and then go into the next plating bath.

If you need to leave the part out for a while before going to the next step, the oxidation will buff off if, but it takes a little extra pressure on the wheel. Just be careful not to buff through the copper and into the plastic.

Practice makes perfect.

Best of luck!

[neeraj_bapat]

I by mistake typed 2 A/in2, I am using a current density of 0.1 to 0.2 A/in2.

Copper is my last layer of metal over plastic (Steriolithography plastic)

I want to avoid oxidation, is buffing the only way out?

[ashcroft01]

neeraj_bapat,

Once you get your final coat of Copper on, the buff and polish it to the shine that you desire, (Be careful not to buff down into the underlying plastic) then you could apply some anti-tarnish compound such as FLITZ LIQUID METAL POLISH.

You could also use the Cape Cod Polishing Cloths to clean and protect your final plate. This may be more suitable than buffing if your plating is thin.

Another alternative and a more permanent solution would be to use some of the VHT Genuine Lacquer as a final clear coat, but the piece would still have to be lightly buffed first.

All of these products are available through the Caswell website.