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Intermediate Level Courses
INTERMEDIATE LEVEL DYEHOUSE COURSE CURRICULUM
Unit 1 Overview of the Leather Industry
Role of leather industry in relation to farming, abattoirs and leather goods manufacture
Tannery processing options
Factors that impact on the global leather industry
Unit 2 Beamhouse / Tanyard Operations
Soaking
Unhairing / Liming
Fleshing
Deliming
Bating
Pickling
Tanning
Basification
Horsing up / Ageing
Sammying
Sorting / Grading
Unit 3 Splitting to Neutralization
Splitting
Split substances
Grain split
Flesh split
Shaving
Reasons for wetting back
Wetting back times
Wetting back chemicals
Reasons for rechroming
Rechroming times
Rechroming chemicals
Rechroming processes
Reasons for neutralization
Different neutralization pH's
Neutralizing chemicals
Neutralization processes
Isoelectric point
How to correct or prevent neutralization problems
Effect on the leather of over-neutralization
Unit 4 Retanning
Reasons for retanning
Retanning chemicals
Retanning times
How to correct or prevent retanning problems
Properties imparted by different retanning chemicals
Factors that affect retanning chemicals penetration and fixation
Retanning processes for different types of leather
Unit 5 Dyeing
Why leathers are dyed
Types of dyestuffs
Top dyeing
Intermediate crusting
Crust leather
Powder vs liquid dyestuffs
Colour theory
Factors that affect dyestuff penetration and fixation
Dyeing processes
Unit 6 Fatliquoring
Reasons for fatliquoring
Types of fatliquors
Pre-fatliquoring
Fatliquoring temperatures
Fatliquor chemistry
Fatliquoring processes
How to correct or prevent fatliquoring problems
Emulsion theory
Factors that affect fatliquor penetration and fixation
Unit 7 Fixation
Reasons for fixation
pH vs charge on leather
Isoelectric point
Fixation chemicals
Fixation processes
How to correct or prevent fixation problems
Reasons for final wash
Unit 8 Setting, Drying and Milling
Setting
Hang drying
Toggle drying
Paste drying
Vacuum drying
Properties that different drying methods impart to the leather
Conditioning
Importance of moisture content
Staking
How to prevent staking problems
Milling
Milling times for different types of leather
Unit 9 Crust Leather Testing
Standard sampling position
Conditioning of samples
Conditioning times, temperatures and humidity
Tests carried out on crust leather
Interpretation of test results
Possible reasons for leathers failing tests
Unit 10 Post Dyehouse Operations
Buffing
Impregnation
Leather finishing
Measuring