Tin Plating PCBs

There's no need to buy special lacquer. Save your money for other things.
I use Sherwin Williams clear acrylic lacquer. Easily avaible, not particularly expensive, and works like a charm. I have circuit boards over ten years old that look as though they were made yesterday. I spray the board before populating it--the lacquer melts away at the slightest amount of heat, so there's no problem soldering through it.