Abstract: A cover has been designed to make a sealed chamber over a desired specimen area to control reagent evaporation which is critical for amplifying DNA in slide specimens. The cover is positioned over the specimen and temporarily adhered to, or pushed against, the slide, forming a sealed chamber. Reagents are added through a channel in the cover with a standard pipette and the channel opening is closed to prevent evaporative loss of reagents. The chamber is also designed to relieve internal vapor pressure, which is creating upon heating, thereby facilitating diffusion in and out of cells rather than allowing high pressure to flatten cells against the slide surface. Increasing the height of the chamber upwards toward a neck in the cover allows air bubbles being formed during each cycle to leave the specimen area, while at the same time preventing water vapor loss or partitioning of water vapor condensate.