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Carnoy’s Fluid

Carnoy’s Fluid


Ethanol, absolute60mL
Acetic acid, glacial10mL

Prepare just before use.


Carnoy’s fluid is a very rapid fixative and has been used frequently for fixation when rapidly processed paraffin sections are wanted. For a 1-2 mm piece of tissue only 30 to 60 minutes is required, and dehydration takes place at the same time. It is a good nuclear fixative, but produces considerable shrinkage and cytological distortion. As with most alcoholic fixatives, glycogen is preserved well.

This is the fixative usually meant when “Carnoy’s fluid” is specified. There is another fixative often ascribed to Carnoy, a 3:1 mixture of ethanol and acetic acid, but that is more correctly referred to as Clarke’s fluid.


30 minutes to 2 hours.


Transfer to absolute ethanol.

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.
    Carnoy (1887), Cellule, v. 3, p. 276.