When measuring powder with a spectrophotometer, the measurement value varies depending on the density of the powder and the surface conditions. To avoid errors, special methods are required such as placing a fixed amount of powder into a container of a fixed shape and size and maintaining a fixed surface quality.
If the size of the particles is large, use a spectrophotometer which has a large measurement area, so the measurement surface is averaged and repeatable measurement values can be obtained.
The measurement of semi-transparent objects requires special consideration because the light might pass through the material and the measurement may be influenced by what is behind the object. To solve this problem, increase the thickness of the object to prevent the light from being transmitted completely. Another solution is to put an opaque white surface behind the object.
When measuring objects that have patterns or textures, the measurement value varies according to the location if a small area is measured. The largest possible measurement area should be used, or measurements should be taken several times in different locations and then the average measurement value should be calculated.
Sometimes when the temperature of an object changes, the color of that object will also change.
This phenomenon is called thermochromism.
To measure color accurately using a spectrophotometer, the measurement must be performed in a room with a constant temperature after the measurement object has reached room temperature.