The Oxford English Dictionary defines court plaister as:
"Sticking-plaster made of silk (black, flesh-coloured, or white) coated with isinglass, used for covering superficial cuts and wounds." So called from its being used for the black patches formerly worn on the face by ladies at Court.
Is this the earliest image of Queen Victoria used to endorse a product? Embossed by Dobbs, printed by Whiting and Congreve, circa 1837.