1. Reduced tanning time
2. Increased shrinkage temperature
3. Removal of water from the fiber texture
4. Improvement of the penetration power and uniform binding of the subsequent tanning agents of the main tanning process.
5. Adjustment of the pH value required for final tanning.
6. Avoidance of case hardening.
7. Prevention of loose grain, wrinkled grain or formation of a coarse grain.
8. No change of the desired leather character as regard handles, softness or physical properties.
Possible types of pretannage
1. Chrome tannage (often carried out in the pickling bath)
Pretannage with: | Improvement |
Glutaraldehyde: Polymer tanning agents: Syntans: Alumin tanning agents: Resin tanning agents Alumin sodium silicates: | Cr absorption, fastness to perspiration Filling, fine grain, lightfastness Bleaching, filling Bleaching, firm grain Filling, firm grain, buffing properties Filling, firm grain, exhaustion |
1. Vegetable/synthetic tannange
Pretannage with: | Improvement |
Syntans with small-sized particles: Chrome syntans: Cr. Tanning agents: Alumin tanning agents: Glutaraldehyde: Polymer tanning agents: Polyphosphates: Resin tanning agents: | Penetration of tannin, grain elasticity Penetration of tannin, flexibility Penetration of tannin, resistance to heat Bleaching, absorption of tannin Flexibility, fastness to perspiration Penetration of tannin, filling, lightfastness Bleaching, abrasion Filling, firm grain |
2. Aluminum tannage
Pretannage with: | Improvement |
Glutaraldehyde: Polymer tanning agents: | Softness, fastness to perspiration Shrinking temperature handle |
No comments:
Post a Comment