A solvent dye is a dye

Dye

A dye is a colored substance that has an affinity to the substrate to which it is being applied. The dye is generally applied in an aqueous solution, and requires a mordant to improve the fastness of the dye on the fiber....

 soluble in organic solvents. It is usually used as a solution in an organic solvent.

Solvent dyes are used to color organic solvents, hydrocarbon fuels, wax

Wax

thumb|right|[[Cetyl palmitate]], a typical wax ester.Wax refers to a class of chemical compounds that are plastic near ambient temperatures. Characteristically, they melt above 45 °C to give a low viscosity liquid. Waxes are insoluble in water but soluble in organic, nonpolar solvents...

es, lubricant

Lubricant

A lubricant is a substance introduced to reduce friction between moving surfaces. It may also have the function of transporting foreign particles and of distributing heat...

s, plastic

Plastic

A plastic material is any of a wide range of synthetic or semi-synthetic organic solids used in the manufacture of industrial products. Plastics are typically polymers of high molecular mass, and may contain other substances to improve performance and/or reduce production costs...

s, and other hydrocarbon-based nonpolar materials. Fuel dyes

Fuel dyes

Fuel dyes are dyes added to fuels, as in some countries it is required by law to dye a low-tax fuel to deter its use in applications intended for higher-taxed ones...

 are one use of solvent dyes. Their molecules are typically nonpolar

Chemical polarity

In chemistry, polarity refers to a separation of electric charge leading to a molecule or its chemical groups having an electric dipole or multipole moment. Polar molecules interact through dipole–dipole intermolecular forces and hydrogen bonds. Molecular polarity is dependent on the difference in...

 or little polar, and they do not undergo ionization. They are insoluble in water. They form a colloidal solution in solvents.They have poor (basic dyes) to good (metal complex based) light fastness.

Solvent dyes are used for gold imitation (and other transparent metallic effects) of metallized polyester films. Also used in marking inks, inkjet inks, glass coloration, and so on.

Names of solvent dyes are often generic, of the scheme "solvent <color> <number>", e.g. Solvent Red 24, Solvent Red 26

Solvent Red 26

Solvent Red 26, also known as C.I. 26120, is a purplish red synthetic azo dye. Its chemical formula is C25H22N4O, or 1-Solvent Red 26, also known as C.I. 26120, is a purplish red synthetic [[azo dye]]. Its chemical formula is C25H22N4O, or 1-Solvent Red 26, also known as C.I. 26120, is a purplish...

, Solvent Red 164

Solvent Red 164

Solvent Red 164, also called Oil Red B, is a synthetic red diazo dye. Its chemical structure is 1-Solvent Red 164, also called Oil Red B, is a synthetic red [[diazo dye]]. Its chemical structure is 1-...

, Solvent Yellow 124

Solvent Yellow 124

Solvent Yellow 124 is a yellow azo dye used in European Union as a fuel dye. It is a marker used since August 2002 to distinguish diesel fuel intended for heating from a higher-taxed motor diesel fuel...

, Solvent Blue 35, etc.

Red and yellow solvent dyes are often azo dyes, green and blue ones tend to be anthraquinone

Anthraquinone

Anthraquinone, also called anthracenedione or dioxoanthracene is an aromatic organic compound with formula . Several isomers are possible, each of which can be viewed as a quinone derivative...

dyes.