What is light fastness?
Intro:-
Light fastness is the degree to which a dye resists fading due to light exposure. Different dyes have different degrees of resistance to fading by light. All dyes have some susceptibility to light damage, simply because their strong colors are indications that they absorb the wavelengths that they don't reflect back. Light is energy, and the energy that is absorbed by pigmented compounds may serve to degrade them or nearby molecules. certain Basic type dyes can cause damage when exposed to light.
Unfortunately, ultraviolet is not the only kind of light that causes damage. Visible light is quite sufficient to fade colored materials. In tests using a UV protectant, Dyers LIST members Jerry Trapp and Sally Holmes found that the beautiful but poorly lightfastness blue-violet, Procion type blue MX-7RX, actually showed an increased amount of damage. This was presumably caused by an interaction between the protectant and the dye; UV protectants in glass windows will surely do no harm, whether or not they are helpful. Most likely, UV protection will help protect some dyes, but not others.
To test color fastness in textile to get complete perfect results you need a Weathering equipment called Xenon Light fastness tester
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Procurement, Marketing and Sourcing Specialist
8 年Unit to measure light is Lux
Head of Department MMC (Material Management & Control) & Commercial
8 年Sir, what is unit of measure for light.