According to the FL blurbs, it should works just as well on the plastic zippers. I used it on a Chinese multi-Tool that was supposedly SS, that had rusted at some pivot points and had become difficult to open to get some of the implements out to use. FL surely loosened it up considerably compared to before.I use it and love it. Works great on the stuck metal zippers of my jackets too. Don't forget the hair dryer to heat the metal up.