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Mallory Bleach

Mallory Bleach



Solution A

Potassium permanganate1g
Distilled water100mL

Solution B

Sulphuric acid1mL
Distilled water100mL

Working solution

Solution A1volume
Solution B1volume

Solution C

Oxalic acid1g
Distilled water100mL

Tissue Sample

Most fixatives may be used.


  1. Bring sections to water by an appropriate method.
  2. Place into the working solution for ten minutes.
  3. Rinse well with water.
  4. Place into solution C for a few minutes until the tissue is bleached.
  5. Wash in water.
  6. Continue with the main stain.

Expected Results

There is no observable effect. Subsequent staining is altered in some fashion.


  • Recommendations for the concentrations of potassium permanganate, sulphuric acid, and the proportions of each to use in the working solution vary widely. Due to this, use the concentrations and times specified for individual techniques, if given, in preference to those here.
  • This is a general, mild oxidation procedure, and is used in many staining methods. Its usual effect is to inhibit staining of some tissue components to increase contrast of a stained element. It is sometimes applied to unmask a component and render it stainable.
  • The mixture of permanganate and sulphuric acid produces permanganic acid. Like most per-acids, this is an oxidizing agent. Potassium permanganate is also an oxidizing agent, and is sometimes used without the sulphuric acid, usually within the range 0.1% – 1%, with similar results.
  • More concentrated solutions (up to 10%) may be used to bleach melanin, but may require longer application, particularly for heavy deposits. Stronger solutions will bleach faster, but will be more likely to damage the tissue or remove it from the slide. Eosin staining is diminished afterwards.

Safety Note

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


  1. Drury, R.A.B. and Wallington, E.A., (1980)
    Carleton’s histological technique Ed. 5
    Oxford University Press, Oxford, UK.

Almost every reference text will include details of the Mallory bleach.