Once two colors have been scanned and given numeric values by a spectrophotometer, the difference between them can be measured in units of ΔE (Delta E). A ΔE of less than 1 is not perceptible to the human eye, while a ΔE of 100 means the two colors are the exact opposites. For colors that aren’t important (for example, non-brand specific colors, or even when you want cut vinyl to match your brand color, but really don’t want to pay an exorbitant amount for a custom-made vinyl), a ΔE of less than 5 (perceptible at a glance) is a common tolerance standard. For fairly critical colors, such as brand specific colors on overlays and decals, a ΔE of 3 or less (perceptible through close observation) should be specified. Colors that are extremely critical, such as logos for major brands and Fortune 500 companies, may have an acceptable ΔE tolerance of 1 or less.
It is useful for color specialists to use light booths in combination with spectrophotometers, especially in the case of subsurface prints (remember that window we were looking at the paint through?), because the thickness, cast, and texture of the material can all affect the way that light bounces in the device, leaving us with inaccurate numeric data. Often the ink itself is matched without regard to the material and then tweaked via visual color-matching as needed.
Whatever color standard and tolerance you decide on, Graphics Output is here to help you get your color right. We are happy to sit down and go over options to find what fits your needs. Email us at firstname.lastname@example.org, call 260-748-0577, or request a quote here.
1Wyszecki, G. & Stiles, W. (1982) Color Science, 2nd Ed. NY: Wiley & Sons
See also Color Matching 101 – The Essentials and Color Matching 201 – Beyond Basics.