The colors on the QP card are mixed separately from special pigments and extremely fade resistant. Although the colors are very stable we recommend storing the cards in the absence of all light and humidity for maximum longevity. The practical life of the cards when stored properly is about 6 years.
Some of the colors are mixed to resemble the spectral response of colors in real life: Light skin (#18), Dark skin (#17), Sky blue (#25) and Forrest (#15). The seven neutral patches (#4?10) all have an almost straight spectral response.
In practice this means the QPcard 201 can be used in almost any light condition with almost any camera, without suffering from metamerism
