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A dye is a colored substance that chemically bonds to the material to which it is being applied. This distinguishes dyes from pigments which do not chemically bind to the material they color. Dye is generally applied in an aqueous solution and may require a mordant to improve the fastness of the dye on the fiber. [2]
Broadly, dyes are soluble and become fixed to a substrate via impregnation, while pigments are insoluble and require a binding agent to adhere to a substrate. Dyes, therefore, must have an affinity for the substance they are intended to color. [4] Chemically speaking, pigments can be organic or inorganic, while dyes are only organic.
This is a list of dyes with Colour Index International generic names and numbers and CAS Registry numbers. This list is incomplete; you can help by adding missing items.
E)-Stilbene itself is of little value, but it is a precursor to other derivatives used as dyes, optical brighteners, phosphors, and scintillators. [25] Stilbene is one of the gain mediums used in dye lasers. [26] 4,4 ′-diamino-2,2 ′-stilbenedisulfonic acid is a popular optical brightener used in some laundry detergents.
Lightfastness is a property of a colourant such as dye or pigment that describes its resistance to fading when exposed to light. [1] [2] [3] Dyes and pigments are used for example for dyeing of fabrics, plastics or other materials and manufacturing paints or printing inks.
Reactive dyes have good fastness properties owing to the covalent bonding that occurs during dyeing. Reactive dyeing is the most important method for coloring cellulose fibers . Reactive dyes can also be applied on wool and nylon ; in the latter case they are applied under weakly acidic conditions.
Direct dyes, a class of dyes largely for dyeing cotton, are water-soluble and can be applied directly to the fiber from an aqueous solution. Most other classes of synthetic dye, other than vat and surface dyes, are also applied in this way. The term may also be applied to dyeing without the use of mordants to fix the dye once it is applied.
Vat dyes are a class of dyes that are classified as such because of the method by which they are applied. Vat dyeing is a process that refers to dyeing that takes place in a bucket or vat. The original vat dye is indigo , once obtained only from plants but now often produced synthetically.