Mordant





A mordant is a substance used to set dyes on fabrics by forming an insoluble compound with the dye. It may be used for dyeing fabrics, or for intensifying stains in cell or tissue preparations. A mordant is either inherently colloidal or produces colloids and can be either acidic or base (chemistry).

Mordants include tannic acid, alum, chrome alum, sodium chloride, and certain salts of aluminum, chromium, copper, iron, iodine, potassium, sodium, and tin.

Iodine is used as a mordant to set the first dye in gram stains.

Phosphomolybdic acid is used as a mordant to set light green when staining with Masson's trichrome stain.

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