International School of Tanning Technology

MODULE 2 COURSE CURRICULUM

The correct process sequence in the dyehouse
The role of each stage
How each stage is monitored and controlled
The chemicals involved with each stage and possible substitutes
The quality improvement or damage that occurs during the dyehouse processes

Wetting back

Wetting agents and water tension enzyme slackening acid use use of dicarboxylic acids for loose chrome binding

Rechroming

Theory of high basicity vs reactivity properties imparted by chrome tanning materials dye evenness batch to batch variation
Grain-setting
Theory of drum impregnation retanning agents influence on collagen structure acrylic binding mechanism

Neutralising

Neutralising agents vs neutralising syntans structure and function of auxiliary syntans iso-electric point shifting the iso-electric point over-neutralisation complete vs incomplete neutralisation

Retanning

Melamine, urea-formaldehyde, dicyandiamide resins replacement, combination, lubricating-acrylic, metal-complex syntans lignosulphonates polyurethanes condensed and hydrolysable vegetable tannins the binding mechanism of the retanning agents with collagen properties imparted by the retanning agents the effect of the retanning agents on the leather grain effects obtainable with various retanning agents

Dyeing

The theory of colour polychromatism vs trichromatism dyestuff structure dyestuff compatibility dyeing terminology factors that affect dye penetration and fixation dye levelness dyeing defects powder vs granular vs liquid dyestuffs dye effects obtainable with dye technology dye application methods

Fatliquoring

Emulsion theory HLB fatliquor make-up types of raw oils synthetic oils fatliquor manufacture fatliquor structure chemical softening and the extended model of fatliquoring mechanical softening incomplete fatliquoring hand / machine oiling and stuffing hydrophobic fatliquors pull-up effects fatliquor defects

Fixing / washing

Iso-electric point and fixing power chemical fixing agents ageing as a fixing mechanism fixing defects influence of washing on processing

Crust leather testing

Strength endurance permeability / shrinkage dye uptake / chemical uptake COD
Fogging