Abstract: Apparatus for dispensing a mixture of mutually reactive liquids, such as a resin and its hardener, comprises a gun head having a bore opening therethrough to define a mixing chamber. The mutually reactive liquids are fed along separate paths through the head and into the bore to mix in the bore and be dispensed through one end of the bore. A valving rod is reciprocable in the bore, between a forward position in which the valving rod seals the liquid inlets from each other and occupies the mixing chamber, and a rearward position in which the valving rod opens the mixing chamber and permits the flow of liquids into the mixing chamber. One of the liquids is fed along the outer surface of the valving rod in the retracted position of the valving rod and along most of the length of the valving rod which was disposed in the mixing chamber in the forward position of the valving rod. In this way, mixed liquids are washed from the valving rod by that one component, in the rearward position of the valving rod.