Introduction


Colorants are characterized by heirability to absorb or emit light in the visible range (Zollinger, 2003, p.1). Light of a given wavelength is perceived as the indicated color. Theperception of color by the human eye does not solely depend onabsorption wavelength, although it is crucial, but alsoon the shape of the bands involved. Man has used natural colorants long years ago. Substances that impart color to a material are dyes andpigments.


In term of chemical structure, colorantscan be inorganic or organic compounds. Both groups can be subdivided intonatural and synthetic representatives. (Christie, 2001, p. 24).


Colorants classified in to twoseparate ways, either according to their chemical structure or according to themethod of application, they are dyes and pigments. Every color is representative of light that is at a particular wavelength orfrequency. For example, what we consider as red is lightthat has approximately 780 - 620 nm wavelength (Christie, 2001, p. 24).


When light interacts with molecules,the molecules absorb the energy from that particular light. This energy can dosomething to the molecule. For example, certain wavelengths can make molecules vibrate, make the bonds rotate, or make theelectrons within the molecule become more energetic.Certain molecules can only absorb certain energies. (Argonne National Laboratory, 2005).

 

 

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Originallypublished in: New Cloth Market, July-2010