Advanced Level Tanning Course / Module 1

ADVANCED LEVEL TANNING / MODULE 1

LEARNING OBJECTIVES

Students need to fully grasp the concepts covered on the Intermediate Level Tanning Course.

The following are covered in this module:

Skin Structure

The gross morphology, histology and the chemical make-up of all skin components

Detail on the hair, collagen, collagen-water, glycosaminoglycans and other inorganic and organic structures

Stress is placed on the development of the 1°, 2° , 3° and 4° structures of collagen and the consequent differentiation of structure into tissues

Knowledge of skin structure relative to processing

Skin Types / Defects

Modification of the tanning process to the skin type

Different animal skin types include cattle (calf and adult), pig, sheep (wool & hair sheep), goat, ostrich and reptile

Defects that occur in the natural animal (breed differences), living animals, slaughter preservation, storage, tannery processes

Causes and effect on preservation is covered

Preservation

Preparation of the hide / skin for preservation and problems associated with curing

Mechanisms of action of the various preservation methods

Monitoring and control

Bacterial decay and growth conditions

Beamhouse

Correct process sequences

Role of each process

Chemicals involved with each stage and possible substitutes

How each stage is monitored and controlled

The chemistry of collagen modification by preparative stages of tanning

The latest machinery developments, monitoring and controlling

Soaking

Reason for the process

Influences on soaking

Latest development to improve soaking

The role of enzymes

Soaking problems

Unhairing / Liming / Reliming

Chemistry of disulphide bridge cleavage, modification of collagen, lanthionine formation and osmotic swelling

Latest developments to improve quality

Influences on the processes

Reasons for the process

Deliming / Bating

Ammonium salt deliming process

Chemistry of calcium hydroxide and sodium hydroxide alkalinity

Latest developments to improve quality

How the deliming / bating process is influenced

Enzyme activity

Pickling

Reason for the process

Preparation of the hide / skin for the penetration of chrome

Removal of glycosaminoglycans and splitting of fibre bundles

Pickling chemicals

Latest developments to improve quality

Physical chemistry of electrostatic swelling and its prevention

Bleaching

The mechanism of pigment breakdown

Bleaching agents and their formation in a CIO2 acid environment

Removal of noxious gases and excess bleaching agents

Tanyard

The correct process sequence

The role of each stage

The chemistry involved with each stage and possible chemical substitutes

Tanning

Reason for the process

Factors that affect penetration & fixation of chrome

Hydrolysis of chrome salts

Chrome tanning mechanisms

Ionisation of carboxyl and amine groups

Basification

Reason for the process

Chemicals used

Schorlemmers basicity

Role of pH in tanning processes

Consequences of loose tanning agents

Olation and oxalation

Testing

Shrinkage temperature

Boil test

Calamari test

Chrome content of effluent / leather

pH measurement of liquor and the skin

Density

Temperature

Speed

Machines

Sammying

Shaving

Splitting lime/ blue

Fleshing

Drums / paddles / hide processors

Beams and fleshing knives

Raceways