The Gardner-Delta Color Comparator permits easy, effective visual evaluation of varnishes, drying oils, fatty acids and other oil derivatives, lacquers, and similar transparent colored liquids. It consists of two basic parts: a comparator of 18 precision glass color standards and a special illuminator which provides a color-corrected light source.

The comparator is an arrangement of two disks, each containing nine optical polished glass filters (color standards) ranging in color from water white through deep amber. The standards are equally spaced around the edge of the disk and a channel between the disks holds a tube containing the sample. This tube can be seen in the center of the three openings on the front panel so the sample may be compared simultaneously with two adjacent standards. Values of the standards appear in the apertures on the front side of the comparator.