The most common hematoxylin in the H&E staining is the alum hematoxylins (Suvarna et al., 2015). Aluminum is used as the mordant, which can be either aluminum potassium sulfate (potash alum) or aluminum ammonium sulfate (ammonium alum). It provides good nuclear staining by staining it red, which is then converted to blue-black after washing with weak alkali solution.

Mayer's hematoxylene