Sometimes when I rhodium plate my ring comes out looking smoky,
almost with a burnt look. I am careful with the voltage. Two and
one-half volts are what the instructions say. I electroclean the ring
first, then rinse it in distilled water. I also keep the solutions
covered and clean. Since rhodium is so expensive, I hate to buy more
unless I have to.
Last time I had that problem I suspected my rhodium was
contaminated. Other peoples rhodium was whiter. I was plating a lot
of silver models. I also plated some dubious 9k. I asked around and
was told that the silver had leached into the mix, or I might have
used up my rhodium. There was no saving it. I bought some more. I
added some to the bad mix. It is good enough for the dubious stuff. I
keep the other for metals I am more confident with. Later I was
asked why my rhodium isn’t as good as another guys. I went to see
him and he is a cleanliness freak and that is your answer. He uses a
sealed jar to store it and perfectly cleans his beakers. The way he
does it looks like overkill. Air reaches the mix only when he is
plating. I emulated his procedures and my results are much better.
The biggest improvements for me come from how well I clean my stuff.
You also need to electroclean the piece at least twice and move the
anode.
At the repair shop I work at we have a three step process. First we
electroclean the piece, rinse in distilled water, dip in acid
activator, rinse again, and then to the rhodium, and a final rinse.
Each step has its own rinse jar of distilled water. Adding the acid
activator step has extended the life of our 5 gram bottle of rhodium
more than fourfold as opposed to only electrocleaning alone. You can
get the acid activator from Gesswein (Item Number: 210-0938 EarthGold
Acid Activator, 1 lb.) or Stuller (Item Number: 45-2040 2LB
ACTIVATOR).
I also (as Phillip has mentioned) have had a major improve on
quality due to a freakishly fastigious cleansing and storing regime
being introduced. I am experimenting with different cradles at the
moment to try to get better results. I use copper wire but am trying
some titanium. It just seems to me the titanium consumes alot of the
rhodium.