A specimen processing system is capable of processing specimens carried on slides. The specimen processing system can sequentially deliver slides and opposables to specimen processing stations. The specimen processing stations can use the opposables to apply a series of liquids to the specimens. The applied liquid can be moved along the slide using capillary action while the specimen processing stations control the processing temperatures. The applied liquid can be in a fluid-carrying gap. The opposable can contact the slide to vary a cross section of the fluid-carrying gap.