Some Facts about Light fastness Textile Dyes and Pigments used in the industry vary to a great extent in terms of their resistance to light sources and this phenomenon is called as ‘Light -fastness of Textiles’ .Sunlight materials electromagnetic radiations of several wavelengths. Visible range of spectrum (400 - 700 nm), ultraviolet (300 - 400 nm) and infrared (700 - 1400 nm) become the main constituents which reach to the earth’ s surface. Colored materials like Textile, Leather and Paper when subjected to the photons generated from the sunlight have tendency to destroy the coloring constituents of dyes and pigments. Further prolonged exposure may even cause destruction to the substrate itself. Partial destruction of the coloring material in dyes and pigment is known as fading. The other detrimental effect could be change of tone or change of brilliance of the color. A consumer when buys an apparel is attracted to the colors and if this color is altering / fading during usage or laundering, the consumer gets frustrated, so it is responsibil ity of dyestu ffs manufacturers to safeguard and guide the processor about the fading behavior of a dye/pigment applied on the substrate. There are many factors influencing the light fastness behavior. Substrate and their diffusion properties. Substrate preparation. Chemical nature of the fiber. Method of the application. Delusterants in the substrate. Finishing chemicals applied Usage of the article. Dye-fixers used. Choice of colors and their combination. Perspira tion and exposure to light. Prolonged exposure to light. Oxidative or reductive nature of dye fading reaction. Unfortunately, the tag labels on articles do give wash instruction but the guidance and sustainability of the article to multiple exposures to light are not so popular. There are hardly any indicators to guide the consumer regarding the resistance of the article towards sunlight fading. Uncontrollable Factors Content of UV amount in the sunlight: As more is the UV component more photons of their light and more will be the effect on color with respect to fading. The intensity of temperature from the sunlight falling on the article.
Factors to be considered to meet the light fastness for textile substrate
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Some Facts about Light fastness
Textile Dyes and Pigments used in the industry vary to a great
extent in terms of their resistance to light sources and this
phenomenon is called as Light-fastness of Textiles.Sunlight
materials electromagnetic radiations of several wavelengths.
Visible range of spectrum (400 - 700 nm), ultraviolet (300 - 400
nm) and infrared (700 - 1400 nm) become the main constituents which
reach to the earths surface. Colored materials like Textile,
Leather and Paper when subjected to the photons generated from the
sunlight have tendency to destroy the coloring constituents of dyes
and pigments. Further prolonged exposure may even cause destruction
to the substrate itself. Partial destruction of the coloring
material in dyes and pigment is known as fading. The other
detrimental effect could be change of tone or change of brilliance
of the color. A consumer when buys an apparel is attracted to the
colors and if this color is altering / fading during usage or
laundering, the consumer gets frustrated, so it is responsibility
of dyestuffs manufacturers to safeguard and guide the processor
about the fading behavior of a dye/pigment applied on the
substrate. There are many factors influencing the light fastness
behavior.
Substrate and their diffusion properties. Substrate preparation.
Chemical nature of the fiber. Method of the application.
Delusterants in the substrate. Finishing chemicals applied Usage of
the article. Dye-fixers used. Choice of colors and their
combination. Perspiration and exposure to light. Prolonged exposure
to light. Oxidative or reductive nature of dye fading reaction.
Unfortunately, the tag labels on articles do give wash
instruction but the guidance and sustainability of the article to
multiple exposures to light are not so popular. There are hardly
any indicators to guide the consumer regarding the resistance of
the article towards sunlight fading. Uncontrollable Factors
Content of UV amount in the sunlight: As more is the UV
component more photons of their light and more will be the effect
on color with respect to fading.
The intensity of temperature from the sunlight falling on the
article.
Relative Humidity Higher the humidity, higher could be fading.
This factor has impact on the wet-light
fastness and hence fading in varying humid environments comes
into the picture. Atmospheric contaminations. Amount and quality of
perspiration also play a crucial role in deciding the amount of
fading. Laundering pattern. Repeated laundering and exposure to
sunlight or a single exposure to sunlight also
affects the degree of fading. Some Guidelines
Higher the depth, better the light fastness. Only right choice
of colors can help in getting better light fastness and any
corrective
actions would fail to improve the light fastness. Right choice
of textile chemicals to ensure that no detrimental effects of them
on the light
fastness of dyed articles occur. When use of more than one color
is made in making a shade, the final light fastness of
the article will be based on the lowest light fastness
constituent of the dye in the recipe. This is more important when
we want to ensure on-tone behavior of fading after exposure to
light (one component fading to smaller extent will give a further
ugly appearance to the shade than one with on-tone fading).
