I'VE NEVER HEARD OF THIS. I HAVE ALWAYS JUST TAKEN THE TUBE OF WAX AND RUBBED IT ON THE STRING THEN TAKE MY FINGERS AND RUN THEM UP AND DOWN THE STRING. THE FRICTION GENERALLY PUTS THE WAX ON THE STRING EVENLY. I DON'T KNOW HOW A ZIPLOC BAG WOULD MAKE ANY DIFFERENCE, BUT THEY OBVIOUSLY KNOW SOMETHING THAT WE DON'T.