I used to use a product called Ebenol-C for black velvet finish. It
is a copper blackener. I’d very heavily copper plate the area to be
blackened, actually burning the plate on so it crystallized slightly
(grew many micro crystals on the surface). This was put into a hot
solution of Ebenol-C producing a permanent optically flat black that
was resistant to ultrasonic cleaning and steaming, but not pickle or
acids.
Does anyone know where this or another product like it can be
purchased?
Thanks
Jeffrey Everett