Summary for silicon bronze plating Discussion
Silicon bronze plating is discussed as a way to get a more durable black or decorative finish than fragile patinas. Wayne Emery asked about a durable black coating, and Rocco Turino asked about a less shiny finish for a polished sculpture. Ted Mooney said plating onto silicon bronze should not be especially difficult, aside from activating the surface with a fluoride-bearing acid before copper plating; from there, silver, nickel, gold, or black chrome could be applied. In a later question, Jared Smith asked how to activate nickel on silicon bronze and how long freshly plated nickel can sit before the next step. James Watts answered that for brush plating, the transition from chemical step to rinse to the next step should happen very quickly, and he said keeping the part wet while changing devices helped adhesion. He suggested that “freshly plated” means only seconds, not days.
Q. I am very interested in finding a way to put a DURABLE black coating on silicon bronze. The usual patina processes are far too fragile.
Thanks in advance!
Wayne Emery
Jewelry Design Studio – Tacoma, Washington, USA
2001
Q. Wondering what options I have to finish a polished silicon bronze sculpture? Prefer something not too shiny, like nickel or silver to prevent oxidization which occurs with bronze.
Rocco Turino
Artist – London, England, UK
2004
A. Hi Wayne; hi Rocco. Hopefully a more experienced plater will correct me if I am wrong, but I don’t think plating onto silicon bronze presents major difficulties apart from activation with a fluoride-bearing acid, then copper plating. You could pick silver plating, or nickel plating, or other plating on top of the nickel plating, like gold or black chrome.
Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com – Pine Beach, New Jersey
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Q. We are seeking a finish for a silicon bronze casting – an enclosure for an underwater floodlight. We would like a dull black color similar to black oxide on steel. What is a similar blacking process that can be used on a silicon bronze casting (alloy CA873)?
Ben Gallant
Product Designer – Berkeley, California, USA
July 14, 2008
A. Hi Ben. A simple patina-style blackening process on silicon bronze will probably be neither sufficiently corrosion resistant nor durable.
Copper-nickel-black chrome may give you the corrosion resistance and color you seek. Good luck.
Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com – Pine Beach, New Jersey
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Need project assistance? $100/hr.
Q. Hello All,
What would be the best activation method for the plating of nickel onto silicon bronze (cda 655). Does it matter if the process is electro or electroless? I have read that a 5% sulfuric acid solution is ideal, but someone also mentioned a substance that can be brushed on and then rinsed off (maybe something with phosphoric acid?)
Ultimately, I will be brush plating gold as a finish. I have read that you do not need to activate freshly plated nickel. What defines freshly plated nickel? Obviously, environmental issues come into play but lets say a 60 degree Fahrenheit, 60% humidity room with no human contact. Is the nickel suitable for plating without activation for 5 days or 5 months or what?
Thanks in advance to all that reply. I have gained so much great info from this forum.
Jared Smith
– Carbondale, Illinois, USA
December 9, 2012
A. Five seconds is a lot closer to reality. Brush plating needs to go from a chemical step to rinsing and then the next chemical step as rapidly as possible. I found that keeping the part wet while I changed devices made a great deal of difference in adhesion.
James Watts
– Navarre, Florida