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Eosin is tetra bromofluorescein (a substituted xanthene), a red acidic dye and fluorochrome. The dye is very soluble in ethyl alcohol. Eosin, 2% w/v is the most commonly used as counterstain for hematoxylin and it is also used for monochrome staining of bacteria.

May Grunwald's Blood Stains are basic and acidic dyes which induce multiple colours when applied to cells. The basic component of white cells (i.e cytoplasm) is stained by the acidic dye and they are described as eosinophilic or acidophilic. The acidic components (e.g. nucleus with nucleic acid) take blue to purple, shades of the basic dyes and they are called basophilic. The neutral components of the cell are stained by both the dyes.

Decolourizer is one reagent used in this process to provide the color differentiation. A decolourizing solution is used to remove the Primary Stain from cells which bind it weakly and then the counterstain (like safranin) is used to provide a colour contrast in those cells that are decolourized.

Lugol's iodine is used as staining solution to detect intestinal protozoa and helminth ova or larvae. It is rapid contrast dye that is added to direct wet mounts of fecal material to aid in differentiating parasitic cysts from host white blood cells. Lugol's iodine stain the protozoan nuclei and intracytoplasmic organelles brown making them easier to identify.

Negative staining method permits visualization of the usually transparent and unstainable capsule of many organisms, most importantly Cryptococcus neoformans. Nigrosin consists of a suspension of fine particles of carbon. These form a dark background.