A dye differs from a pigment in that a dye
- A. is always black
- B. is insoluble and sits on the surface as fine particles
- C. is soluble in the medium and becomes attached to the fibre
- D. contains no colour at all
Explanation
A dye dissolves and bonds to the fibre by ionic, hydrogen or covalent bonds, so the colour becomes part of the material and resists washing, whereas a pigment is insoluble and must be held in place by a binder as in paint. This is why a dyed cloth keeps its colour through the wash while a painted surface can flake. Fastness to washing and to light is the main measure of dye quality.