Washing (wet back) →
Re-chroming →
Retanning (syntan approx. 20-30%) →
Dyeing →
Fat-liquoring →
Setting out →
Vacuum drying →
Hang drying →
Vibrating (Staking) →
Toggle drying →
plating →
Ready for finishing→
Vegetable Tannage is the earliest one to practiced tanning. The oldest exploitation of plant polyphenols in technology is their ability to stabilize collagen in skin against putrefaction, The plant polyphenols that can be leached out of vegetable matter or plant parts have the power to react with the collagen, rendering it resistant to biochemical degradation, but more importantly remaining soft after wetting-drying cycle.
Tannin parts present as defence mechanism against insects, because they impart a stringent taste to the plant material, The reactivity of polyphenols is referred to as 'astringency' because they react with protein. Precipitate gelatin from solution with the active agent (Polyphenol) under investigation in a tanning type of reaction - This is the traditional test for astringency.
Vegetable tannins are extracted from plant may be done with water or with organic solvents.
The extracts typically contain three fractions of materials
Non-tans are low molecular weight fraction, with a molecular weight <500,
Tans are the medium molecular weight fraction. with mol. wt. 500-3,000
Gums are the high molecular weight fraction, with mol Wt. >3000
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