Mallory Bleach

Please read the Notes section.

Solution A
Potassium permanganate 1 g
Distilled water 100 mL
Solution B
Sulphuric acid 1 mL
Distilled water 100 mL
Working solution
Solution A 1 volume
Solution B 1 volume
Solution C
Oxalic acid 1 g
Distilled water 100 mL

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.


  1. 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.
  2. 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.
  3. The mixture of permanganate and sulphuric acid produces permanganic acid. Like most per-acids, this is an oxidising agent. Potassium permanganate is also an oxidising agent, and is sometimes used without the sulphuric acid, usually within the range 0.1% - 1%, with similar results.
  4. 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.


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.




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