When interpreting degrees of lightfastness into production requirements - real-world conditions need to be taken into account.The 'Wool Scale' lightfastness classifications are: When exposed in the same manner as the print for the same length of time, the level of fading of the printed solid is compared to that of the equivalent strip of wool to provide a value indicating the lightfastness of the print. The blue wool scale is not a linear scale but is rather logarithmic, so that each increase in level is greater than the previous. The scale ranges from 8 (excellent вЂ“ very low rate of fading) to 1 (very poor вЂ“ extremely fast fading). The scale consists of 8 different strips of wool, each dyed with a blue dye of differing lightfastness. The 'Blue Wool Scale' is the internationally recognized method of quantifying lightfastness, defined under the British Standard BS1006. Fadeometer, Max Tolerance: 2-30 hrs shows fading and loss of gloss Tint - Max Tolerance: less than 1 month with fading Fadeometer, Max Tolerance: 5-25 hours shows fading and loss of gloss Tint - Max tolerance: less than 1 month with fading & loss of gloss Fadeometer, Max tolerance: 120-160 hours shows fading and loss of gloss Tint - Max tolerance: 24 months with fading

Fadeometer, Max tolerance: greater than 240 hrs. Tint - Max tolerance: greater than 12 months. Some typical fade resistance numbers for sheetfed 4/C process inks based on outdoor exposure near the equator: The covered section of the press sheet is the control against which you can compare the fading of the exposed part. Simply take a presswork sample and cover half (front and back) with heavy black card. They will know the characteristics of the pigments in their ink formulations and can suggest alternatives that may provide better fade resistance - though often at the expense of some other attribute like rub resistance, color vibrancy, or cost. If resistance to fading is an important criteria for a print project, the best source of information is the vendor supplying the inks. The results are interpreted with the aid of a chart that correlates the number of hours a printed sample lasts in the fadeometer to the equivalent exposure to direct sunlight taking into account the amount of UV light that different regions receive based on their latitude. Although it does not exactly duplicate the effect of prolonged exposure to natural light, it is still an effective indicator of the degree of light stability and of the comparative resistance to fading. The arc emits an intense actinic light which in a matter of hours approximates the destructive effect of a much longer period of ordinary daylight. Ink manufacturers use fadeometers, along with known ink pigment characteristics, to test fade resistance by exposing the print to light radiation produced from a carbon arc or xenon tube. Fading is much more complicated than is usually realized as it depends on environmental factors (light, heat, humidity,), the particular pigments being used, and the substrate the ink was applied to. The main cause is exposure to light (especially UV), which causes the ink/paper system to oxidize. The inks used in print production will all fade over time. Unfortunately, ink, like most things in life, is not permanent.

Printer has ink but prints faded