Computer-color matching usually employs a subset of Kubelka-Munk equations which require that each specimen analyzed be at complete hiding. This set of equations is preferred because they are simpler than their counterpart equations that operate at incomplete hiding. On the other hand, in coatings and plastics very often colorant specimens must be utilized that, either because of their nature or concentration, fail to qualify as being at complete hiding. This communication examines techniques for handling such cases and makes recommendations for obtaining the theoretical opaque reflectance of the specimens from measurements over both black and white. In addition, the article recommends a new relationship that more aptly characterizes the contrast ratios required than previous methods have done.