Color Measurement and Its Application in the Rubber Industry

Abstract

Abstract The object of this paper is to bring to the notice of rubber technologists the recent advances which have been made in the science of color measurement and its applications. As the demand for colored articles increases, it becomes necessary to use a more specific way of recording color than to say that an article is “rose pink” or “olive green.” The use of standard samples is cumbersome in regard to storage, and may be misleading in the case of rubber products, as they are liable to color changes. The increasing use of raw rubber in the form of latex has raised the question of the measurement of its “whiteness” as a guide to its quality. It has been suggested also that the transparency of thin dried latex films could be used for this purpose. Both these methods entail the measurement of the color of almost white objects. MacAdam has shown that it is difficult to judge the whiteness of articles by direct vision. He asked 30 observers, half of whom were women, to arrange white objects in order of increasing whiteness. The arrangements showed great divergence, and the observers were unable to repeat their observations. When these samples were classified by means of a suitable colorimeter, consistent and reproducible results were obtained by different observers. Visual observations are subject to the effect of many variables, and are therefore so misleading that it at once becomes apparent that such determinations can only be successfully carried out with a colorimeter used under carefully standardized conditions. Besides the measurement of the whiteness of latex such problems arise as the covering power of pigments, especially of white pigments, the use of dyestuffs in brightly colored articles, the transparency of rubber lacquers and varnishes, all of which require a measurement of color in some form or another.