COLOR FASTNESS TO LIGHT

Solar radiation, temperature, precipitation and oxygen give a start to an aging process of the materials, influencing at the same time many of their physical properties.

The FADE-OMETER Atlas Ci 3000+ + is an apparatus with controlled environmental conditions used to determine the light fastness of various materials.
The instrument accelerates discoloring by means of control of the temperature on the black panel, the temperature of the chamber, humidity and light (UV, visible and infa-red). The Ci 3000+ is an apparatus with a xenon lamp with controlled radiation that enables a constant exposure of light.
Light filters that can easily be interchanged define the spectrum of emission of the xenon lamp so as to imitate the various conditions of natural sunlight in the environment where the various materials will be used. A xenon lamp that has been correctly filtered is the best imitation available of typical sunlight.

The leather test-piece is inserted in the instrument together with a blue scale, made of 8 strips of wool fabric, of different standard dyeing. In this kind of test, the test-piece is submitted to a light, simulating natural light, but much stronger. To be able to quantify the amount of light that hit the sample during the test, half of the blue scale is covered vertically and then put inside the instrument together with the test-piece. The scale and the test-piece will both undergo some variations due to exposure to the rays; comparing the part of the scale that had been covered and the exposed one, we notice the "quantity" of light that hit the test-piece. The amount of light needed to discolor a blue stripe increases from the lighter stripe to the darker. A small amount of light will only discolor the lighter color (the one at the bottom of the picture). An average amount of light will discolor 4 stripes, whereas a lot of light will discolor all of them. The last modified stripe expresses the quantity of light the leather test-piece was exposed to.

So, the test result will be something like: "After exposing the test-piece to a quantity of light equal to 3 of the blue scale, we experienced a discoloring equal to 4 of the gray scale" (see next page for a description of the gray scale).

RECOMMENDED VALUES

Recommended light fastness, according to the current European Standard of Upholstery Leather are: