Discoloration from repeated machine washes and early fading in manufacturing textiles can indicate a lack of quality. Colorfastness tests have gained international significance. There are many methods that can be used to test for colorfastness and dyes. These are the most important:
Grey Scale to Assess Change in Colour: The Grey Scale can be used to assess changes in leather colour in colour fastness tests such as wash fastness and perspiration fastness. This scale is made up of nine pairs each of grey colour chips, which represent a visual contrast and difference.
Grey Scale to Assess Staining. This Grey Scale can be used to assess the staining of dyed leather during colorfastness tests. The staining of wool or cotton fabrics in wash fastness, sweat fastness, and others. Nine pairs of grey color chips make up the scale, each one representing a visual contrast and difference.
– Colour Fastness Leather to Light: This method can be used to determine the resistance of leather to light. The Xenon lamp emits light at a wavelength that is close to daylight. Under controlled conditions, the side of the leather sample to be tested is exposed to light from a Xenon lamp. Eight blue-dyed wool standards (blue range) are also used. By comparing the leather’s fading with that of the blues standards, the light fastness of the leather is determined. To aid in the evaluation, the fading is usually done within two exposures.
– Leather Colour Fastness to Mild Cleaning: The resistance to mild domestic washing in water and leather colour is measured by the colour fastness to hand washing. Not only can there be colour changes in leather but also coloured substances that may bleed or stain it when washing.
– Color Fastness of Leather to Wash: This refers to the resistance to washing in domestic machine laundry with water. Not only can leather color changes occur but also colored substances can bleed through the leather and stain nearby textile materials.
– Colour fastness of small samples to dry cleaning solutions: This method can only be used to determine the leather’s resistance to dry cleaning solutions. This method does not address the suitability for dry cleaning composites or leather garments.
– Color Fastness of Leather to Migratory into Plasticized Poly(vinyl chloride). The color fastness of leather to migration into plasticized poly(vinyl chloride) at 50 C. The leather sample to be tested will be placed on white pigmented paper.
The composite specimen and plasticized PVC are exposed to heat under pressure for 16 h at 50 C.
Colour Fastness of Leather to Perspiration – This refers to its resistance to prolonged action of artificial perspiration solutions.
A Chrome-free leather is another way to test. This leather is becoming increasingly popular, especially for automotive upholstery applications. Chrome-tanned leather is superior in many ways to chrome-free leather. Chrome-free leather is known to be more susceptible to heat and UV than chrome-tanned leather. This is especially true when it comes to colorfastness and mechanical properties. Leather properties are affected by temperature, humidity, and UV radiation. However, the role of humidity and its interaction with UV radiation and temperature on the leather property is not well understood by the leather industry. This information is required for the formulation of antioxidants to protect chrome-free leather against heat and UV damage.