Drying of finishing drying after spray finish

It is essential that a proper drying method be selected and employed after application of the finishing floats. The importance of this process is often under estimated and it is not performed correctly for reasons of time. This results in defects in the finishes and also on the leather. Drying is required each time a finish coat has been applied.
Airing off:
The leathers are suspended or hanging on bars at ambient temperature or in slightly in heated rooms, mostly without movement of air. This is a gentle method without risk of over drying.
Through-feed hang-drying or horizontal drying
The drying temperatures are 60-80 ⁰ C in the middle of the drying section and lower in the feed-in and discharge areas. Adequate air exhaustion should be ensured to remove the air saturated with humidity.
1st application of base coat
The drying temperatures are 60-80 ⁰ C in the middle of the drying section and lower in the feed-in and discharge areas. Adequate air exhaustion should be ensured to remove the air saturated with humidity.
To achieve an even penetration of the base coating float it is important that the leathers have uniform residual moisture content all over the surface. Uneven drying results in a different degree of swelling of the fiber surface and thus in loose grain wrinkled grain or impaired adhesion.

Inadequate drying
It results in abrasion of coats which have previously been applied by padding or brushing and thus in unlevelness. In subsequent nitrocellulose finishes it causes impaired adhesion and/or greying.
Over drying at excessive temperature
It results in a top that is hardly wet able and causes formation of streaks or droplets and adhesion problems. Residual moisture increases the tackiness of film of thermoplastic binders may become brittle. Furthermore, fatty substances and plasticizers may migrate into the outer finish layers.