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Unna’s Alum Hematoxylin

Unna's Alum Hematoxylin



Hematoxylin3 gDye
Ammonium alum300 gMordant
Distilled water600 mLSolvent
100% ethanol300 mLSolvent
Sublimed sulfur6 gStabiliser

Compounding Procedure

  1. Dissolve the hematoxylin in the alcohol.
  2. Dissolve the Alum in the water.
  3. Combine the two solutions.
  4. Leave the solution at room temperature to ripen (days).
  5. Add the sulfur and mix well.


  1. Bring sections to water with xylene and ethanol.
  2. Place into the staining solution for an appropriate time.
  3. Rinse well with water.
  4. Differentiate with acid ethanol if necessary.
  5. Rinse with water and blue.
  6. Rinse well with water.
  7. Counterstain if desired.
  8. Dehydrate with ethanol, clear with xylene and mount with a resinous medium.

Expected Results

  • Nuclei  –  blue
  • Background  –  as counterstain or unstained


  • The sulfur is added after the solution has properly ripened.
  • Unna said that the sulfur stabilized the solution in the oxidized state for some time. Others considered glycerol to be superior for this purpose.
  • Ammonium Alum dissolves in water at the rate of about one gram in 7 mL, and it is almost insoluble in ethanol. The formula should therefore require about 90 grams, so the amount specified is in considerable excess.
  • The staining time should be determined by trial.
  • Acid ethanol is 0.5% – 1% hydrochloric acid in 70% ethanol.
  • Blueing is done with alkaline solutions such as hard tap water, Scott’s tap water substitute, 0.1% ammonia water, 1% aqueous sodium acetate, 0.5% aqueous lithium carbonate etc.

Safety Note

Prior to handling any chemical, consult the Safety Data Sheet (SDS) for proper handling and safety precautions.


  1. Gray, Peter. (1954)
    The Microtomist’s Formulary and Guide.
    Originally published by: The Blakiston Co.
    Republished by: Robert E. Krieger Publishing Co.
    Unna, (1892)
    Zeitschrift für wissenschaftliche Mikroskopie und für mikroskopische Technik, v.8, p.438