Copy Cad / Zinc Trouble

[Rab]

Hi Guys, I am having mixed results with my kit, the last job I did I had the amps up a little higher, and my plate turned out very dark, according to the manual I had "burnt plate" , as it was not decorative I thought I could live with the dark result, but after only 2 days sitting on the bench in the workshop the parts had corroded and rusted very badly. Is this what happens if the plate is "burnt". I am using a lab type power supply with current limiting feature, even when I turn the power supply up full 20 amps and 50 volts ( I know this is far too much) I still do not get any bubbles forming from the part in the bath - which is how the manual tells me to confirm I am using too much power, anyone any ideas why this is no happening, and why my parts rusted almost immediately

On the plus side, I have been getting some excellent results from my nickel plating kit !

[dadkar2]

Re: Copy Cad / Zinc Trouble

You'll get better results if you run the tank at around 120F with plenty of agitation. Keep the anodes clean; ie, if they get coated with oxide, clean them up with Scotchbrite and rinse with distilled water. Run the current at 100mA per sq in or less. Don't run it higher because this will, as you have found, simply darken and oxidize the plating.

Keep the right amount of brightener in the mix. In my tanks, too much brightener works against me and actually makes the parts duller.

I'm confused as to why your parts rusted. That doesn't make much sense. Are you sure you achieved any plating at all? ie, did you actually measure the current flowing during the plating operation to make sure it was actually plating?

Ken

[seanc]

Re: Copy Cad / Zinc Trouble

Rab:

regarding "burnt" plate, give us more to go on. How big is your plate? and how many amps was going through it? Here's a link to a truly burnt plate compared to good plate:

Burnt plate

And your power supply, does it have meters for current & voltage? And the voltmeter is going up to 50v? Then you don't have a good connection. The voltage should be quite low, @ .5 - 2 v, depending on the size of the part.

If you never get any bubbles, something's certainly wrong. If it not fizzing furiously, you can't be burning it. Even small parts will "fizz" a little. Here's some videos of a part I plated. It's @ 45 sq-in surface area. The fizzing is quite evident:

Part fizzing & agitation

Since you're not getting any bubbling, I have to ask, do you have the power supply connected correctly? Positive to anodes, negative to the part?

Regarding corrosion, if the power supply was backwards (or had no connection at all), the part never plated, so it rusted. If power was correct, did you seal the part after plating, either w/WD-40 or chromate? And was it rinsed thoroughly?

As for "decorativeness", are you using the zinc brightener? Un-brightened parts will never be "decorative", they will always be dull grey. Here's a comparison of un-brightened vs brightened parts:

Bright vs non-bright plate

I have to disagree w/Ken on the temperature. The electrolyte calls for a range of 60-90? F. I get my best results at the lower end, 65-70?.

Ken, I'm curious, why do you recommend 120?? When I first had difficulties (which turned out to be insufficient current density), Caswell had me try 110?, and it was a disaster.

Sean