Standardization Procedure for Two Instruments for Color Measurement

A standardization method was developed to check that a color measuring instrument will perform satisfactorily and that measurements made with it are within acceptable tolerances. Four types of materials were selected to test the instrument a white opal tile to check nominal 100 reflectance an amber glass filter to check low and high photometric scale and the wavelength scale at mid range a gray porcelain tile to check the reflectance scale at mid range and a pair of polyester plastic samples to check that proper color differences are being measured and calculated. Two instruments were used in this study, a Hunterlab D54 spectrophotometer and a Diano Match-Scan spectrophotometer. Each was interfaced to a mini-computer for collecting data on the test materials. Based on statistical studies of the measurements made on the instruments, two slightly different computer programs were developed which provide guidance for the operator of the instrument through the standardization procedure and make comparisons of the current measured data to previously established norms and tolerances for the same material. The computer programs are fail-safe in the sense that the instrument cannot be used to perform routine tests unless all of the standardization criteria are met.