Pen plating over rhodium plated silver

Dear all,

We are producing a silver line that its final look will be in two
tones, the yellow part will be pen plated with 18k gold and the
remaining majority-section of the item will be RH plated. What we are
doing is assemble and polish the items, Palladium plate it then RH
plate it, and then we are pen plating the required section in yellow.
The issue that we are encountering on the Gold pen plated parts
(usually a twisted wire or filigree) is that the plating is not
sticking and can be easily rubbed off with a cloth.

I did contact couple of friends from Technic Inc, and they advised
to re-activate the surface (after RH plating) by dipping the item in
a mild HCL solution and then pen plate.

Now, there is the traditional masking off the areas that need to
stay white and bath plating for a heavy deposit, but as I mentioned,
these section are the majority of the item, in fact it is in most
cases 90% of the item, so the option of masking is out of the picture
hence it is labor intensive.

At the end what we want is the yellow pen plating to be strong
enough to hold and NOT to be rubbed of that easily.

Any advice or suggestion will be highly appreciated.

Thank you all in advance
Dikran Nodznaia

The first thing to try is a fresh solution. A spent solution will
plate a surface that can be rubbed off,

Tom Arnold