Patent ID: 6917424

Claim:
A process for making single pigmented dispersions which comprises: (a) charging the components of a single pigment liquid dispersion into a mixing vessel; (b) grinding the components together to form a liquid dispersion; (c) passing the liquid dispersion through a transmittance cell coupled to a spectrophotometer; (d) measuring the spectral transmittance of the wet dispersion over the visible spectrum; (e) calculating the optical density of the dispersion at two specific wavelengths from the transmittance measurements and comparing the ratio of optical density values at the two specific wavelengths to that of a known standard dispersion to determine achievement of the desired particle size; (f) repeating steps (b)-(e) at least once in the event the dispersion is not within the desired particle size tolerance until the dispersion being manufactured is within said desired particle size tolerance; and (g) determining the pigment concentration of the dispersion and its relative tinting strength as compared to a standard by comparing the optical density value at a selected wavelength to that of a known standard of equivalent particle size, or by comparing the absorbance or transmittance spectrum of the dispersion with that of a known standard, either by integration or by fitting.