Unna's Alum Hematoxylin

Ingredient Amount Function
Hematoxylin 3 g Dye
Ammonium alum 300 g Mordant
Distilled water 600 mL Solvent
100% ethanol 300 mL Solvent
Sublimed sulphur 6 g Stabiliser


Compounding procedure
Dissolve the hematoxylin in the alcohol.
Dissolve the Alum in the water.
Combine the two solutions.
Leave the solution at room temperature to ripen (days).
Add the sulphur 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


  1. The sulphur is added after the solution had properly ripened.
  2. Unna said that the sulphur stabilised the solution in the oxidised state for some time. Others considered glycerol to be superior for this purpose.
  3. 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.
  4. The staining time should be determined by trial.
  5. Acid ethanol is 0.5% - 1% hydrochloric acid in 70% ethanol.
  6. 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.


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




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