Cheap coating to protect silver plating while etching copper with cupric chloride.

Hello
I am an engineer in the electronics industry trying to develop a process that would reduce the cost of our product. The process involves partially etching copper with cupric chloride with out affecting the silver plated areas. Cupric Chloride does not aggressively attack the Silver plating and I thought that I can just submerge the whole assembly in the etching solution. It turns out that the Cupric Chloride affects the silver and turns it dark gray. I need to find a way to resurrect the nice shiny silver plating after the etch process or find a cheap coating I can apply to the silver before the etching process.

Almost any paint will do provided it is pore free and hardly will you find anything cheaper. Only problem is to mask before painting. Conventional paint remover ⇦ on eBay or Amazon [affil link] or solvents do not harm either copper or silver.