Gram Stain Kit, 7 Dropper Bottles

The Gram stain is one of the most widely used differential staining techniques in microbiology, sorting bacteria into two groups, Gram-positive and Gram-negative, based on how their cell walls respond to a sequence of stains. This kit supplies the reagents needed to carry the procedure through all four of its stages in seven dropper bottles, letting students see the color difference that reflects a real structural distinction between bacterial types.

The staining sequence begins with crystal violet, the primary stain that colors every cell violet. A potassium iodide solution then acts as the mordant, forming a complex with the crystal violet that anchors it inside the cell. Denatured ethyl alcohol serves as the decolorizer, the critical differentiating step: Gram-positive cells, with their thick peptidoglycan walls, retain the violet complex, while Gram-negative cells lose it and turn colorless. A final safranin counterstain colors the decolorized Gram-negative cells pink, so the two groups are easy to tell apart under the microscope, violet for Gram-positive and pink or red for Gram-negative.

Each reagent is packaged in a dropper bottle for controlled application to prepared smears, with alcohol supplied in the largest quantity since it is consumed fastest during decolorizing. A comprehensive instruction manual walks through the Gram staining procedure step by step and includes a safety data sheet for each chemical, and every bottle carries GHS-compliant labeling with safety and storage information. The reagents are intended for laboratory and educational use in bacterial identification, and because the kit contains flammable alcohol, it ships under the 49 CFR 173.4 small-quantity exception for domestic ground transport.