Tioxide Group Services Limited

Alastair Orr Mackenzie

Peter Barry Howard

James Henry Hatfield

Edmund John Lawson

Provided herein is a device useful for measuring the fineness of a dispersion of particles in a liquid vehicle. A device according to the invention includes a light source, a means for mounting a film of said vehicle of increasing thickness, and a means for producing an electronic image of said film, in which these elements are positioned relative to one another so that the light the imaging means receives is predominantly light reflected from regions of the surface of said film which are disrupted by protruding particles. This is achieved by configuring the device so that the image producing means is aimed into the dark field below the light source, with the image producing means being directed generally at an angle below the angle of reflection of any light reflected from undisrupted regions of the surface of the film. In one preferred embodiment, the image producing means is oriented to be inclined at an angle of approximately 12 degrees to the plane of the surface of the moveable carrier which is part of the means for mounting a film.

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Darlington, United Kingdom

Alastair Orr Mackenzie