A well-known, if extremely rough, convention in the world of color measurement says that in CIEL*a*b* or CIEL*C*h space, a dE* value of less than one indicates that two colors are visually indistinguishable to the human eye. The reality is far more complex than this. The limits of visual perception actually differ depending upon which portion of color space is being discussed.
Metamerism is a visual phenomenon which can be caused by a number of different factors. The result is that two samples may look the same under some conditions and different under others.
The most common cause of metamerism is that the pigmentation used to make a match is different than that found in the standard. The spectral curves are different even though the L*a* b* values are the same. The effect of different light sources reflecting off of the different materials results in a visual color difference between the two under some lighting conditions.
Weathering is a routine performance test to determine durability of paint and plastics under extreme weather conditions. The most popular areas for weathering studies are located in AZ and South FL. Samples can also be placed into chambers that can simulate changes in temperature, humidity and UV levels. More…