1. StopperThe stopper on top can be made from glass or Teflon. It is imperative that it fitstightly, so that the solution does not leak out when the separatory funnel isinverted. If a ground glass joint does not fit perfectly, a minute amount of greaseis applied to the upper part of the joint to get a better seal.The stopper has to be removed when draining the lower layer. If the stopper werenot removed, a vacuum will build up above the liquid part and prevent the solutionfrom draining. After some time, the vacuum will suck air in (from the stem) andthe phases will mix again.2. Stopcock plugThe stopcock plugs can be made from glass (left side) or Teflon (right side). Itis important to have a good seal here as well. Again, a very small amount of greasecan be applied to the glass plugs (shown on the left) to improve the seal andallow for better movement of the plug. The grease should be used sparingly, becauseit will clog up the hole in the plug! The glass plug has to be held in place with a metal clip. Teflon plugs usually possessa thread (some glass manufacturers offer those version for glass plugs aswell), which allows to place a nut on it to hold it in place. Teflon plugs shouldnot be lubricated! In order to find out which plug is needed, the glass joint has to be examined. Glassstopcocks require a ground glass joint (looks milky if clean and is rough onthe inside). Teflon stopcocks use a polished joint (clear). Do not attempt to fita glass stopcock into a teflon joint! The slopes on the plugs are slightly differentand the joint will break! producing area:CN payment:LC , TT ,etc