A mordant dye is a substance that strengthens or fixes a dye or stain. When dying fabric, a mordant dye joins forces with the dye to form a coordination complex that aids in the dye's adhesion to the fabric. A mordant dye is a name given to this multivalent coordination complex. Additionally, mordant dyes enhance stains on tissue preparations or microbiological slide preparations.
Work Principle of Mordant Dyes
The majority of mordant dyes are colloidal coordination complexes made of polyvalent metal ions that react with a dye or stain. The mordant dyes create a covalent chemical connection using hydroxyl oxygen. Additionally, an oxygen atom and another form a coordinate link. It's possible for the coordination complex to be basic or acidic. The covalent and coordinated bond formation allows the coordination complex or lake to bind to fabric or tissue. The compound is made to connect to fibers or cell components thanks to the lake's electrical charge. Additionally, the complex is more difficult to wash away because of its heavier molecular weight than the color alone. The coordination complex is insoluble, whereas the dye may be water-soluble.
When a mordant dye is added during the dyeing or staining process affects the outcome as well:
- Pre-mordanting or on chrome: The mordant dye is applied to the substrates first, then the dye. On the fiber, the coordination complex develops.
- Adding the mordant dye to the dye bath is known as meta-mordanting or metal chrome. In the dye bath, the coordination complex develops. Meta-mordanting only functions with a small number of dyes, however treating the substrate in one step is easier.
- After dyeing and before being treated with a mordant dye, the material is chromed. On the fiber, the coordination complex develops similarly to pre-mordanting.
The fibers are impacted by whether the mordant dye is added before, during, or after dyeing in addition to the color and its stability. For instance, pre-mordanting or post-mordanting do less damage to cloth than adding an acidic mordant dye to an acidic dye. In other situations, a mordant dye alters the substrate's texture.