Sorry, SC Johnson has given it some name changes over time, but this is it:
It is an acrylic clearcoat that self levels and is easy to clean up if you make a mistake. It is a long-standing trick in the scale modeling world (coating canopies for clarity, protective coat for decals, etc). This is the stuff people used on their SS Stormtrooper armor to turn the matte finish the proper gloss.
Will it protect my knob?