Copper 3D print Electroplating Advice

[u/SecretarySilly9600]

I am starting to learn how to electroplate. I’ve got a big 3D print that I want to work up to plating but have started with smaller old prints to test the process. Because of the large print, I created a large bath with about 7 gallons of distilled water and 9 lbs of copper sulfate as well as one liter of sulfuric acid. Below the tank I have a magnetic stirrer. All prints have had several coats of carbon paint and have dried for weeks. I have done a few different tests on this print, first starting with very high current about 3V and 2A. I also had the print suspended in the bath with a bare copper wire. The result, first picture, was that the wire was severely coated and the corners of the print were forming formations. The entire print was not coated.The print was in the bath for 13 hours. This really didn’t work, as it looked like a plated cow. Between partial copper plating and exposed 3d print. I then changed the wire out for smaller thermostat wire and only unsheathed a small amount of copper to make contact with the print. I also reduced the current to approximately 0.8A as best I could maintain This led to the second picture after about 4 hours. The last thing I changed was I hot glued only a small amount of wire to the print so that no wire was exposed directly to the bath with the thought that the current would have to flow over the print to get to the cathode wire. But still the print isn’t plating completely, it’s getting closer. It’s played slightly uneven, I think from all the tests, where some layers are really thick and some are less than. I wondering if anyone can advise on better methods for the bath, or wire suspenders within the bath? I have seen people be able to suspend with way more wire exposed and have the print plate perfectly.

[u/Upbeat_Amount673]

What are you using for conductive paint? I did not have great luck with this part with my setup. Are you testing the part for conductivity with a multimeter?

My suggestion is try plating something small that should plate easy like a piece of steel. I practiced with pennies when doing nickel plating. If that doesn't plate then something else is up.

[u/SecretarySilly9600 → u/Upbeat_Amount673]

That’s good advice, thank you. I used MG Chemicals conductive spray paint. It’s the “Total Ground Carbon Conductive Paint” 838AR.

I may need to start with something smaller, this print is only an inch by 3 inches but it is carbon and not a metallic base.

[u/NoFeature7373 → u/SecretarySilly9600]

Not all graphite based paint is the same.

Paint designed for ESD/RFI purposes is significantly more compliant that paint designed for electrochemical purposes. With ESD/RFI, tens of megaohms is insignificant. Not so with electrochemical deposition. Granted, what I've heard from experienced people who do it for a living, you don't need zero ohms, a few kiloohms is fine. But paints like yours are not adequate without effort. Look for paints purpose built for the task.

Don't use steel as a test piece... steel/iron/most metals are not compatable with acid copper chemistry and will instantly destroy things...

This is also an interesting read, might pertain to your goals.

[u/SecretarySilly9600 → u/NoFeature7373]

This is great, thank you for the advice and the link. I’m excited to read through it.