flash copper

[fly]

Does anyone have trouble with flash copper on alum. such as small blisters. Does anyone have any tricks to help prevent the blisters?

[SRT_Mike]

I have done a lot of the flash copper plating. I am plating a piece of 0.020" 6061-T6 Aluminum that is about 20 sq-in with an intricate pattern cut into it (creating a lot of thin sections, etc).

I first used a battery charger - copper bubbled and basically fell off. I then used my super-duper nice power supply where I can control the volts and amps. They recommend 1 amp per 10-15 sq-in of surface. This would mean I should use around 2 amps at 1-6 volts. However, I have found that if I turn it down to about 2 volts and .75amps (for the whole thing), I get a nice finish. I am not too concerned with the copper thickness (thinner is better since it uses less copper to get the job done). I get a beautiful, blemish free copper finish that sticks very well. I know it sticks well because I dry it then plastic-bead blast it to a perfect finish then clear-coat it with paint. In cases where my finish was not well attached it bubbled and peeled off.

Here is my process

1) Sand the aluminum until it's nice and shiny all over. Make sure you get ALL low spots and get it really perfect.

2) Wash it off in the sink with dishwashing soap, rinse until its totally clean of soap

3) At this point its dripping wet. I shake off the water a little and then put a wire through a hole in the corner and dip it in zincate. I dip it for 10-15 seconds. It turns dark gray in 5-7 seconds. I rine it off again, very well.

4) Attach a copper wire to the corner, put it in the copper tank which I have already gotten heated to the correct temp. I put the anode in, connect the power, put part in, then connect cathode to my part

5) After 10-20 seconds the zinc coating is being eaten off. In a few minutes I have a nice copper shine. I let it plate for 30-45 minutes at about 2-2.5 volts and about 0.75 to 1.0 amps.

6) When finished plating, I rinse it off and pat dry. It comes our virtually perfect

I started having problems with bubbling like you do, but I got rid of them. I turned down the voltage (I was doing 5-6 volts at about 2-2.1amps). That eliminated about 50% of my problem. Then I made sure I cleaned the part VERY well. I sand it until its shiny all over with 320 grit sandpaper, then I take it to the sink, lather my hands up with soap, grab my part and massage the soap into all areas, then I use a toothbrush to scrub it, then rinse it off very well. I noticed that if I am careful to ensure I sanded my whole part, I have NO problems, EVER. If I miss a spot or there is contaminants on the part before plating, the copper bubbles at that point.

HOpe it helps! I was a bit frustrated at first but now I can plate with 100% perfection EVERY time!

[all2fast]

This problem has been causing problems for about 4 weeks. The real problem is that my aluminum is cast and it is pourus. I have electro cleaned it, baked it, boiled it, and just about everything else. What I found is that it is not the copper that is causing the problems it is the zincate. Although I have tried it without zincate and that does not work neither. The last fair to good experiement I had was to degrease, rinse, pickle 3 for a few seconds only, rinse, then into the zincate for a quick dip NOTHING MORE and then let it start to drip dry and some crustations will form and I just did a quick dip in the pickle 3 once more followed by a good rinse and then straight to the copper bath. The only problems I am having right now is that I have plated this aluminum piece several times and I left the old copper on it. This should not be an issue but it is on this particular cast piece. At the interface between raw aluminum and the past copper I get minimal bubbles. Anyway if you hear of something or have complete success in the above let me know.