Difference between dye and pigment

[fog37]

Hello Forum,

What is the chemical difference between a dye and a pigment? Are most objects around us colored by pigments or dyes? Both are responsible for giving color to objects...

I know that pigments are insoluble while dyes are soluble...fog37

 

[Borek]

Are you sure these things are defined precisely enough to make classification always possible? Or - are you sure there are no substances that can be classified as both?

Also note that "solubility" is a too not well defined. Everything dissolves to some extent. Whether - for practical purposes - we call something soluble or insoluble, often depends on application.

 

[fog37]

Hello Borek,

I agree about solubility: it all depends on the solvent used.

As far as the distinction between dye and pigment, I am not sure. I always hear about pigments in relation to color...

 

[Bystander]

From Wiki, "A distinction is usually made between a pigment, which is insoluble in its vehicle (resulting in a suspension), and a dye, which either is itself a liquid or is soluble in its vehicle (resulting in a solution). A colorant can act as either a pigment or a dye depending on the vehicle involved. In some cases, a pigment can be manufactured from a dye by precipitating a soluble dye with a metallic salt. The resulting pigment is called a lake pigment. The term biological pigment is used for all colored substances independent of their solubility."

 

[Chestermiller]

In textile manufacture, pigments are particulates and dyes are soluble colorants. A widely used pigment is TiO2.

Chet