alvaschein
Active member
Hi all
After trying different methods to get the gold off the plated pins (AP, nitric acid), I wanted to try a new one - reverse electroplating. I made a Pb anode and small Cu container for the plated pins, filled a beaker with 100 ml of 98% sulphuric acid and connected to the power. The first few seconds it looked like in the youtube vids, with the bubbles coming from the anode. But then it suddenly stops. First I thought there is a short between anode and cathode. But nothing. Then I checked te DC supply - also OK!
To be sure I changed the DC supply and tryed again with the same result.
OK, so I went to the lab and took an adjustable DC/Amp supply with a range of 0-30 V and 0-5 A. Same effect as above. Well, finally I checked the amps and found that in the first seconds the current rises very fast but also falls very fast to zero. I made different attempts, waiting from a few seconds to a few minutes and found, the longer I wait the higher ist the initial current before dropping again.
For me that means that there is an increasing resistance between anode and cathode which causes the current drop.
Does anybody know this effect? Is there a chemical effect causing it? Am I doing something wrong? How can I solve this problem?
Thanks very much for your hints.
Roy
After trying different methods to get the gold off the plated pins (AP, nitric acid), I wanted to try a new one - reverse electroplating. I made a Pb anode and small Cu container for the plated pins, filled a beaker with 100 ml of 98% sulphuric acid and connected to the power. The first few seconds it looked like in the youtube vids, with the bubbles coming from the anode. But then it suddenly stops. First I thought there is a short between anode and cathode. But nothing. Then I checked te DC supply - also OK!
To be sure I changed the DC supply and tryed again with the same result.
OK, so I went to the lab and took an adjustable DC/Amp supply with a range of 0-30 V and 0-5 A. Same effect as above. Well, finally I checked the amps and found that in the first seconds the current rises very fast but also falls very fast to zero. I made different attempts, waiting from a few seconds to a few minutes and found, the longer I wait the higher ist the initial current before dropping again.
For me that means that there is an increasing resistance between anode and cathode which causes the current drop.
Does anybody know this effect? Is there a chemical effect causing it? Am I doing something wrong? How can I solve this problem?
Thanks very much for your hints.
Roy
