How to Measure Color With a Photospectrometer
A photospectrometer, also called a spectrophotometer, is a device that measures light intensity in different parts of the spectrum.
The first commercial use of a photospectrometer for measuring color was in the paint industry where it useful for matching paint colors for touch-up painting, such as might be performed in auto body work. In the late 1980s commercial printers began to used photospectrometers to measure color to help match colors particularly in new print runs of an existing publication. Other industries that use photospectrometers include the textile industry and the pharmaceutical industry.
Set the aperture on your photospectrometer to the largest possible setting for the sample you wish to measure. The larger the sample size you are able to measure, the more accurate your reading will be. Make sure that your aperture setting is not so large that it includes areas with colors other than the one you wish to measure.
Use a specular gloss port if the color you wish to measure has a glossy surface such as a magazine page or a shiny paint surface. In some photospectrometers, your device will automatically exclude the glossy reflectance, but if your device does not offer this feature, you will need to adjust the photspectrometer manually.
Perform a diagnostic test on your photospectrometer. A white-tile calibration should be performed daily. Other diagnostic tests should be performed on a weekly basis.
Rotate the object you wish to measure to take four or more separate readings. The multiple readings will help to rule out any possible irregularities and will give you a more accurate reading.
Find and save the average of these different readings. You should create a sampling technique that specifies the number of readings that you will take each time you do a reading, and that when the readings are averaged and remeasured, should have a difference of not more than .15 DE units.
Each photospectrometer operates a little bit differently. If possible, consult the instruction manual for your device to ensure that you are using it properly.