Solvent dyes are the class of dyes that gets soluble in the solvents of organic nature. They are generally introduced in the organic solvent as a solution. As a general tendency the solvent dyes do not ionise. Many of the solvent dyes are typically the Azo dyes that has in fact lost the ability for ionising due to change in their molecular arrangement.

But in the process they gained the ability to get dissolved in non-polar materials like triglycerides. Because of this the solvent dyes are also called lysochrome dyes.

The Solvent dyes are specifically recognised as dyes of the stated colour, whose method of staining is by dissolving. Some of the popular Solvent Dyes are Solvent Red 26, Solvent Red 24, Solvent Red 164 etc. It is pertinent here that the names of the solvent dyes follows the generic pattern of the scheme, like solvent "color" "number".

When we talk about chemical structures some of the popular chemical structures are the Azo structure that imparts the solvent dyes yellow-red color, Anthraquinone structure solvent dyes that results in green-blue. Other structures for solvent dyes include among others heterocyclic rings, metal complex, pyrazolone, xanthene and ketoamin. One of the prominent application of solvent dye is the Fuel dye.

Solvent dyes have multiple uses. They are applied to color organic solvents, waxes, hydrocarbon fuels, lubricants, and a variety of other hydrocarbon-based nonpolar materials. Other popular applications include in inks, waxes, chemical tinting, etc. They are also used in paddle dyeing of wool skins and furs, as also in rectifying imperfect dyeings by spraying from solvent solutions.

However, the most popular application of solvent dyes, must be their role in the plastics industry. Within this industrial parameter, solvent-based dyes are used to add colors to a large variety of solid materials. Example can be given of PVC, acetates, nylon, polyester, acrylics, PMMA, polystyrene, PETP and styrene monomers etc.

Given here is a few of the popular solvent dyes along with its uses that will clearly represent the utility of the solvent dyes.

Color Index Name	Applications
Solvent Black 5	Spirit soluble, synthetic resins, nylon, polyester
Solvent Black 7	Synthetic resins, ball point and felt pen inks, shoe polish, rubber paint
Solvent Orange 20	Lightfast, spirit-soluble for flexographic and gravure inks
Solvent Yellow 13	Lightfast, spirit-soluble for flexographic and gravure inks, plastics
Solvent Red 24	Extensive use in biological applications that includes demonstrating fats, lipo proteins and triglycerides present in tissues as a biological stain