Fabric Quality Control -How to improve the colorfastness to light
Fabric Quality Control for some special markets is essential than for other ones. For example, Our customer in the Middle East area have complained colour fading in thermal bags. Therefore a colleague mentioned making a bag cover for bag. But to protect the thermal bags from fading to sunlight, therefore try to make a bag cover for it. I don’t think this is a good choice. 2 reasons:
- The colour of the cover might fade too, dyeing mills say the colourfastness to light reaches 3-4 the most, does it make sense?
- The extra charge for the cover is a lot, the material charge+labour cost for a bag cover, I don’t think it is a little bit.
Fabric Quality Control – colorfastness to light vs Sun Resistant
As a matter of fact, to improve the colourfastness to light and Anti-UV, is not the same thing, although they are some connections. They are totally 2 concepts. I will try to make thing simple and explain as below.
Anti-UV(sun resistant), is a treatment to the fabric with agent called Anti-UV chemistry, which can absorb the UV, then reduce the UV going through the fabric. Some umbrellas use this fabrics.
Now you may ask why the colourfastness to light is poor. That is because sunlight(mainly UV) hurts/damage the dyestuff, destroys the molecular structure of dyestuff, then its colour fades. The molecular structure of dyestuff for different colours is different, some are durable to sunlight, some are not. Therefore some colour the colourfastness is good and some are not. Basically, the brighter colours especially the colours with fluorescence might be poor in colourfastness to light.
Fabric Quality Control -How to improve the colorfastness to light
In one word, we can improve the colourfastness to light by changing the use of dyestuff, some colours the present dyestuff is good enough, while others need use better dyestuff. So There are two ways to develop a new material, 1 change the dyestuff to use, and 2 if that colour can not find a suitable dyestuff, then change the colour, ie. give up the colour, select other colour instead.
As to Anti-UV finish, because the agent used can absorb UV, then this finish can improve the colourfastness to light for the fabric. But it is limit, usually improve 0.5 grade, the most 1 grade. So if the dyestuff itself is poor in sunlight, this improvement doesn’t make sense, too.
Fabric Quality Control
To have a better understand, I would like to explain a few concepts as below.
Sunlight is composed of 3 kinds of electromagnetic waves: 1 infrared ray, which contributes heat; 2 visible lights, which contribute colour we see; and 3 UV, which contributes hurts and damage. The character of UV is strong going through.
In the years when I was a student, we concerned about the colourfastness to light much, as we wanted our clothes to be fresh in colour after 2-3 years wearing, even more, As I had only 1 or 2 clothes :), at that time, sunlight is the only way to dry clothing. Now who wants to wear one cloth everyday for more than 2 or 3 years? more than that, we can dry the clothing by heat now. So we do not concern much about this colour fastness to light any more . Only in the special market with special climate in Middle East, this problem becomes a problem again. I think we can solve this. We can consider it case by case at the beginning.
So the most efficient way to improve the colourfastness to light is, to choose and consider the dyestuff carefully.
