This is a simple a relatively inexpensive instrument for evaluating the fastness to light of colored materials.

 The standard fading lamp is mercury tungsten fluorescent (MBTL). This lamp combines the tungsten spectrum, which is rich in red, with the mercury spectrum modified by fluorescent phosphor results of exposure to the MBTL lamp correlate very well with both xenon arc and daylight.

 The light Fastness Tester itself is convenient and compact. It fits easily onto a standard laboratory bench. The instrument is equipped with a pre-settable timer, which controls the duration of test. Another timer registers the length of time, for which a lamp has been running. It is recommended to change lamps after approximately 2000 hours.

Specimens (50x10 mm) are stapled o thin pieces of card. The specimens may be strips of cloths, yarns laid parallel, or mats of fiber, combed and compressed, to present a uniform surface. The cards are placed one above the other in rectangular specimen holders. Each specimen holder accepts up to 20 cards. The instrument takes up to 12 specimen holders, a total of 120 specimens can, therefore, be tested simultaneously. However in practice some of the capacity is occupied by the blue wool standards, against which fading of the specimen is assessed.

 On test, the temperature inside the instrument can rise to 40oC above ambient, and as the color of some materials degrades under the influence of temperature as well as light, the specimen holders incorporate a cooling facility. The holders are linked, in series, by plastic tubing, and cold water is circulated through them in order to dissipate the heat. Permanent plumbing is not required. The instrument can be fed from a slow-running tap and drained into sink.

 The light fastness of some textiles can also be dependent upon the humidity conditions during exposure. The effective humidity inside a specimen holder is controlled by introducing a small quantity of saturated solution. For example, a saturated solution of potassium carbonate, which produces an effective humidity of 455 is recommended to obtain the results agreeing with daylight exposure in temperate zone.

A special mercury lamp (MB/U) has been developed to accelerate fading and providing that water cooling is used, correlation with the standard lamp is of a high order. Using the rapid Fade Lamp, Blue wool standard 7 fades to grey scale 4 in 200 hours compared with 320 hours for the standard lamp. The MB/U lamp needs some additional control gear: the rapid Fad Unit. This unit goes between the Light Fastness Tester and mains electrical supply

Light Fastness Tester

Scope: - Our Light Fastness Tester is capable to meet the requirements of the following standard

B.S. 1006 UK/TN