Rhodium pen plating turning Black

Hello Orchidians,

I need help. Recently something has happened to my pen plating. When
I pen plate rhodium it turns black immediately. OK so I changed my
pen tip. I checked my voltage to make sure I wasn’t going over 4
volts. I tried using my disposable pen. I have used both successfully
for quite some time. I got new rhodium. I have tried new
electrocleaner. I have tried new cleaning solutions, longer cleaning
times, different solutions, sonic and ionic. clean distilled water
every time. And I have checked to make sure my positive and negative
aren’t switched. OH I hope someone can help. Thanks in advance.

Jennifer