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Abstract

A linear relation between the logarithm of the color concentration of a diffusely reflect ing colored surface and its reflectance density is derived as a simple extension of Beer's law and confirmed experimentally using a variety of dyed fabrics.

The experimental results indicate that Beer's law is not usually obeyed by the dye present in dyed materials, probably on account of the presence of adsorbed dye aggre gates. It is in fact only obeyed by true solutions or by suspensions of particles of con stant size distribution.

The application of Beer's law to transmission and reflection systems is discussed, and it is shown that a more general relation is obtained by substituting for c, the color con centration factor in the Beer's law formula, the empirical factor ( c/1+ac^x ). where a and x are constants (probably functions of the refractive index difference between the dye and surrounding medium), and x is a simple fraction.

In a test with dyed viscose rayon fabrics it is shown that about 20% of the reflected light is specutarty reflected from the surfaces of lightly dyed fibers.

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References

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Studies in the Light Absorption of Dyes.1

Abstract

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