The leather (2.5 sq. ft to 25 sq. ft) is dyed to meet the customer demand for colourful leather. In the process of colouring, the leather is dyed and pigmented, with binder-based colours. Most leathers are dyed through completely in dyestuff (liquid dye like ink used for colouration of textile material), where the leather is dyed in rotating to absorb the dye without forming a coating layer. The leather then goes through subsequent rounds of pigmentation which imparts smoothness to the surface.
There are 3 main leather types which are dyed in our factory. –
• Aniline Leather - is the absorbent porous leather, which doesn’t go through the pigmentation phase. The dye colours the leather without producing a topcoat paint and thus the resulting product retains the hide's natural surface.
• Suede and Nubuck Leather - are top-grain cattle leather that goes through subsequent Finishing process and gets snuffed or buffed to give it a velvet-like surface. It is resistant to wear and is white or coloured in nature.
The variation in colour on the leather surface is inspected, before dispatching leathers to the customers. Currently, each leather piece is laid down on the inspection bed and the colour window which is demarcated into quadrants is compared with the leather that is being inspected. The worker then visually inspects the colour variations across all the 4 quadrants to give a judgement on their colour match. This process of colour matching relies on worker’s visual ability and is prone to errors.
To mitigate the human intervention and subjectivity involved in inspecting the colour, we need an automated online technique to inspect the colour variation across the leather. The technique would help us to segregate between different leather colours, and sort them as per the corrections needed.
1. The solution adopted should be cost-effective
2. The solution should be online and should not affect the major processes involved in the operation.
3. The solution should maintain uniformity of colour in leather sheets with 100% accuracy.
4. The system should encompass LED/LCD indication to show the colour tone/variation, with customer specified list source with D-65, TL-84.., etc.
5. The system desired should be able to inspect the entire surface of leather all at once.