Following reversal of the aging process, all color matching and mixing is undertaken by Dunn-Edward Paint Company, under the supervision of Snyder & Short Enterprises. Dunn-Edwards technicians first place the original sample in a spectrophotometer which produces a suggested mix ratio. The colors are then mixed by computer-controlled measuring devices, and the initial tint ratio is carefully noted. After mixing, each color is brushed out, allowed to fully dry, and then compared to the original sample under controlled lighting conditions. Because the spectrophotometer rarely achieves a perfect match, the color is then carefully adjusted by the addition of minute amounts of tinting material and the mixing, brush-out, and drying process repeated until a perfect match is obtained. Dunn-Edwards maintains a record of each S&S color and the tinting ratios necessary to produce it so that each subsequent batch of paint will match the original. For security purposes, Snyder & Short also maintains both a computerized and hard copy backup of the mixing formulae.