The use of potassium hydroxide solutions for clearing minute insect specimens, or portions of large ones, is a well-known and widely used procedure. Extreme care, however, is necessary to provide rapidly the exact degree of transparency in the subject. To provide for these requirements an economical heater was designed to warm a micro-culture slide bearing a few drops of clearing solution. The specimen is immersed in the cold solution on the slide, and the slide is then placed on the heater. The requisite amount of current is supplied to the heating element and clearing of the specimen to the exact degree desired can be obtained in a short time while the process is observed through a binocular dissecting microscope.