Résumé : |
Finishing is the final phase in leather processing and the avoidance of problems is critical.
Finishing issues can significantly affect the physical attributes, aesthetic properties, performance and commercial value of the final leather. Attention to detail is vital at various stages of production to ensure the desired performance characteristics of the finished leather and avoid leather problems. Specifically, these characteristics include colour, gloss, feel, adhesion, break, stretch-ability, light and perspiration fastness, water vapour permeability etc.
Some common finish failures encountered by tanners are tackiness, contamination, wet rub fastness, flexing, poor leather break, looseness, adhesion, heat and light fastness, and odour.
The right selection of crust, desired components of finish mix, good housekeeping of finish yard and correct application parameters are paramount to accomplishing acceptable finish properties. Some of the pigments, compact finish binders and fillers tend to settle down and need thorough stirring before use.
The viscosity of mixes needs to be maintained consistently to get good flow properties. Maintenance of auto spray machine with clean spray guns, photo electric cells free of dust contamination, regular scrapping of nylon strings and ideal drying temperature improve the efficiency of operation. The physical performance of the final leather depends on consistent add-on at all stages of roll coating and spray application.
When using a cross linked top coat, due consideration must be given to the pot life of the cross linked mix and safe handling of sensitive nature of cross linkers. |