What is the purpose of adding borax to working Methenamine Silver in Grocott's Methenamine Silver technique?

• A. Buffer
• B. Solvent
• C. Coloring agent
• D. Reducing agent

Answer: (A)

In Grocott's Methenamine Silver staining, developing the reduced silver deposit on fungal cell walls happens best when the environment is reliably alkaline. Borax is added to the working methenamine silver solution to act as a buffering agent, stabilizing the pH during development. This alkaline, controlled pH is critical for the reduction reaction that turns silver ions into metallic silver on the oxidized fungal walls, while helping prevent nonspecific background staining. If the solution’s pH shifts, development becomes erratic—either too rapid or too slow—leading to artifacts. So borax’s role is to maintain pH consistency, not to act as a solvent, coloring agent, or reducing agent.