The document provides information about the leather industry and the leather manufacturing process. It discusses the various stages of processing raw hides and skins into leather, including pre-tanning processes like soaking, liming, bating, pickling, and tanning methods like vegetable tanning and chrome tanning. It also describes different types of leather and their uses in products. The leather industry is an important sector for Pakistan's economy, contributing to its export growth.

1. LEATHER INDUSTRY
Introduction and Uses: Bi Bi Rabia
Types: Iqra Akram
Pre-Tanning Process: Rabia Aziz
Tanning: Areeba Rahat
Finning: Shakila Yasmeen

2. LEATHER
• Leather is a durable and flexible material created
by tanning animal rawhide and skin, often cattle
hide. It can be produced at manufacturing scales
ranging from cottage industry to heavy industry.
• People use leather to make various goods—
including clothing (e.g., shoes, hats, jackets,
skirts, trousers, and belts), bookbinding, leather
wallpaper, and as a furniture covering. It is
produced in a wide variety of types and styles,
decorated by a wide range of techniques.

3. SOME TERMS OF LEATHER
• Tanning: is the process by which the proteins i
n the skin are stabilished, and transforms hide
into leather with strong resistance to water an
d bacteria.
• Crust leather: is leather which is yet to underg
o the tanning process.
• Tannins: are complex mixture of glucocides of
various polyphenol present in the bark of
certain trees.
• Tannery: is a place where leather
manufacturing occur.

4. Leather Industry of
Pakistan
The leather industry in Pakistan is a fast
developing industrial sector of the country
both in terms of its qualitative as well as
export growth. Over the years this industry
has achieved such a remarkable position in
the economic development of the country
that it now ranks the second biggest export-
oriented industry of the country. This
industry has always been positioned on its
commodity status in its quality both the
home and abroad.
The main factor behind its development lies
on the fact that the efforts of tanners in the
country are aimed at increasing the
promotional and marketing expertise which
always result in the raw materials prices
being more immediately reflected in the
selling price of leather. That is why the
sector’s initial trend of exporting the
raw/pickled/wetblue hides and skins has
now given way to imports for value addition
which now constitutes 25 per cent of the
total export demand of leather and leather
made-ups.

5. HISTORY
• At the time of independence day ther were
only few tanneries.
• In 1950 some were established in Lahore
joinig areas.
• In 1980’s saw improve quality of production.
• In 1990’s the leather sector jump to became
the second largest foreing earner for the
country.

8. FORMS OF LEATHER
• Chrome-tanned leather
• Vegetable-tanned leather
• Aldehyde-tannedleather
• Rose-tanned leather
• Synthetic-tanned leather
• Alum-tanned leather

9. Chrome-tanned leather
• It is more supple and
pliable than
vegetable-tanned
leather and does not
discolor or lose shape
as drastically in water
as vegetable-tanned.
It is also known as
wet-blue for its color
derived from the
chromium.

10. Vegetable-tanned leather
• Vegetable-tanned
leather is tanned using tannins an
d other ingredients found in
different vegetable matter, such as
tree bark prepared in bark
mills, wood, leaves, fruits,
and roots. It is supple and brown
in color, with the exact shade
depending on the mix of chemicals
and the color of the skin.
• Historically, it was occasionally
used as armour after hardening,
and it has also been used for book
binding.

12. Aldehyde-tanned leather
• This is the leather that most tanners refer
to as wet-white leather due to its pale
cream or white color. It is the main type
of "chrome-free" leather, often seen in
shoes for infants and automobiles.

13. Rose-tanned leather
Rose-tanned leather is a
variation of vegetable oil
tanning and brain tanning,
where pure rose
otto replaces the vegetable
oil and emulsified oils. Rose-
tanned leather tanned
leaves a powerful rose
fragrance even years from
when it is manufactured.

14. Synthetic-tanned leather
• Synthetic-tanned
leather is tanned using
aromatic polymers such
as the Novolac or Neradol
types (syntans,
contraction for synthetic
tannins). This leather is
white in color and was
invented when vegetable
tannins were in short
supply during the Second
World War.

15. CHEMICAL CONSUMPTION PATTERN IN
LEATHER INDUSTRY
Sl.No Chemical In Kg per ton of hide/skin
process
1 Soaking aids 0-2.5
2 Preservative 2.5-5.0
3 Lime 80-200
4 Sodium sulphide 20-30
5 Sodium chloride 80-100
6 Ammonium salts 10-15
7 Sulphuric acid 12-20
8 Sodium formate 5-12.5
9 BCS 60-120
10 A1 (A1203) 1-20
11 Zr(Zr02) 0-15
12 Vegetable tannins 10-220
13 Synthetic tanning agents 20-60
14 Fatliquors 25-100
15 Dyes 2.5 -20
16 Binders 20-45
17 Pigments 10-25
18 Top coats 20-45
19 Wax emulsions 2.5-5.0
20 Feel modifiers 1-2

17. PRODUCTS OF LEATHER

19. Types of Leather
Full grain leather:The strongest and most durable part of the hide of an animal is just below the
hair. The grain pattern in this part of the hide is very tight, and the leather made from here is
called full-grain leather
Analine leathers: (like Horween’s Chromexcl)are processed using soluble dyes to maintain their
natural markings and texture, and do not have a surface pigment or coating.
Semi-analine leathers : (like most bridle leathers) are treated with pigments and thus conceal
more blemishes and have a more uniform coating, as well as staying more protected.
Protected leathers; have a non-leather coating sprayed or attached to the leather as a
protectant

20. Types of Leather
Top grain leather: is the second highest quality and
has had the split layers separated away. Making it
thinner and more pliable than full grain.

21. Types of Leather
Corrected grain leather:is any leather that has had an artificial grain
applied to its surface.
Split leather:is leather created from the fibrous part of the hide left
once the top grain of the rawhide has been separted from the hide.

22. Less-common leathers
Buckskin or brained leather:The tanning process that uses animal brains or
other fatty materials to alter the leather.
Patent leather: is leather that has been given a high-gloss finish.
Slink: is leather made from the skin of unborn calves. It is particularly soft and
is valued for making gloves.
Deerskin: is a tough, water-resistant leather, possibly due to the animal's
adaptations to its thorny and thicket-filled habitat.
Nubuck: is top-grain cattle hide leather that has been sanded or buffed on
the grain side, or outside, to give a slight nap of short protein fibers, producing
a velvet-like surface.

23. Leather used in specialty products such as
briefcases,wallets,and luggage
Belting leather:is a full-grain leather originally used in
driving pulley belts and other machinery. It is found on the surface of
briefcases, portfolios, and wallets, and can be identified by its thick, firm
feel and smooth finish. Belting leather is generally a heavy-weight of
full-grain, vegetable-tanned leather.

24. Leather used in specialty products such as
briefcases,wallets,and luggage
Napa leather; is chrome tanned and is soft and
supple. It is commonly found wallets,toiletry kits and
other personal leather goods.

25. Leather used in specialty products such as
briefcases,wallets,and luggage
Bycast leather; is a split leather with a layer
of polyurethane laminated to the surface and then
embossed. Bycast was originally made for the shoe
industry, and later adopted by the furniture industry.

26. Leather Manufacturing
Process Technology with
Flow Sheets,
Pre-Tanning Process
RABIA AZIZ

27. Leather Manufacturing Process
Technology with Flow Sheets

28. Flaying: The technical term is used to
denote the removal of hides and skins from the
parental body is called Flaying.
Curing (Dehydate the
Hides/Skins): The temporary
preservation of hides or skin is known as curing.
Curing can be done using by solid salt or brine. The
solid salt method is the more general and is used
worldwide. NaCl used to remove Hyaloglunic acid.
Only well-cured hides and skins produce high quality
leather.
Raw Materials: The primary sources of raw material for the tanning industry are hides
and skins from animals slaughtered for human consumption. The following are the
types of basic raw materials which are being used by this industry:
1. Buffalo hides
2. Cow hides
3. Goat skin
4. Sheep skin

29. Trimming
Soaking
Liming Bating
Deliming
Fleshing Pickling
Pre-tanning (Beamhouse operations)
The steps in the production of leather between curing and tanning are collectively
referred to as beamhouse operations. They include, in order, soaking, liming, removal
of extraneous tissues (unhairing, scudding and fleshing), deliming, bating (including
puering) , and pickling.

30. 2. Soaking: It is a process of rehydration of preserved raw hides or
skins.
Objectives:
• Rehydration
• Removal of Dirt, manure, blood, preservatives
Chemicals:
• Soda Ash or Na2CO3
• Caustic Soda or NaOH
Operation:
• Soaking is carried out in quanity of water which is double the
weight of hides/skins. In this stage bacterial spores, dirt, blood and
salt are washed out.
• Then soaking is carried out in quanity of water which is four to five
times the weight of hides/skins, and soaking agents and
bactericides are used.
Quality Control
• Duration-22to24 hours . Agitate the drum for 10 minutes interval of every
hour
Soaking Paddles:
1. Trimming: The trimming is done by hand to remove any
portion of the hide that could interfere with the subsequent machine
processes, e.g.: the shanks, ears, and snout.
Batch: Trimed hides are sorted for size and weight and formed into
batches.

31. 3. Liming: Liming is a process in which hides are soaked
in an alkali solution. It is performed using a drum and paddle
or a pit.
Objectives:
• Unhairing to remove the epidermic layer
• Swelling of fibre bundles into individual fibres and splitting of
fibres into fibrils
• To remove the natural fats and grease by soponification
Chemicals:
• Sodium Sulfide (Na2S)
• Calcium Oxide (CaO)
Operation:
• When lime is sharpening with sodium sulphide, the sodium
sulphydrate (sharpening agent) formed in the bath, causes
rapid loosening of hair, whereas caustic soda solution causes
vigorous plumbing of hide fibres due to its strong alkalinity
and also saponifies the natural fat in the hides and skins.
Quality Controls
1. pH-12 to12.5
2. Duration- 24 hours
Limed hides and
skins are called
pelts.
Turbo Mixture
for Liming:

32. 5.Deliming: It is an intermediate process between liming and pickling. The deliming
operation in leather processing is a drum/paddle or pit based operation. Fully delimed pelts
produce softer leather while half delimed pelts produce hard types leather.
Objectives:
• Lowering the pH from 12-12.5 to 8.5-9.0
• Remove the lime
• Remove swelling and plumping
• Depleting the pelt
Deliming Chemicals:
• Water
• Acids: Hydrochloric acid (diluted), Sulfuric acid (diluted), Boric acid, Lactic acid, Formic acid,
Acetic acid
• Ammonium salts: ammounium chloride, ammonium sulfate
• Carbon dioxide
Operation:
• In deliming process, the free alkali, which is soluble in water, is removed by washing the pelts
in water. After washing, chemically combined alkali is removed by neutalising it with acids,
acid salts, ammonium salts or substances with acidic reaction.
Quality Control
 pH- 8.2 to 8.8
 Duration depends on nature of the pelt
4. Fleshing: The process of removal of
sticky flesh from the side of the skin or hide on
fleshing machine or by hand is called fleshing.
Desalting Machines

33. 6. Bating: Bating is an enzymetic process in which non-leather
making constitutes such as degraded proteins, colour pigments, grease
and lime soap are reomoved by pancreatic enzymes or proteolytic
enzymes.
Enzymes:
• Theoretically there are three types bating enzymes. They are:-
• Weak bating enzymes-
• Mid strong bating enzymes-
• Strong bating enzymes- There are two types available commercially, they
are:-
I. Alkali bate
II. Acid bate
Operation:
• Wash the pelts and then to carry out partial deliming. In final deliming,
the temperature is raised and the bate is added.
Quality Control:
 pH check- 7.5 to 8.0
 Cross section test- Drip phenolphthalein in the cross section of the pelt
and if it turns into completely colorless, then bating has finished.

34. 7. Pickling: The treatment of delimed or bated pelt with a solution of acid and salt is
known as pickling.
Objectives:
1. Preserve the pelt for further treatment 2. Acidify the pelt, the pH bring
down from 7.8 to 2.8
3. Oxidize hair root and remove if hair remains after liming 4. Remove all swelling and
plumping
5. Produce softer, thinner white pelt 6. Reduce astringency of
chrome tanned leather
Operation:
• The pickle and degree of pickling are of great importance in determinig the quality of leather
and the speed of the tannage.
• Pelts are introduced into the pickle liquor (salt and diluted acid in water) for 10 minutes. The
starting pH is 1.7-2 of pickle bath which gradually increases 2.7-3 due to absorption of acid by
the pelts.
Salts & Acids:
• Salts: 1. NaCl 2. NaSO4 3. HCOONa 4. CH3COONa
• Acids: 1. H2SO4 2. HCOOH
Quality Controls:
• pH- 2.6 to 2.9
• Cross section test

35. TANNING
Tanning is the process of treating skins and hides of animals
to produce leather. ... Tanning hide into leather involves a
process which permanently alters the protein structure of
skin, making it more durable and less susceptible to
decomposition, and also possibly coloring it.
Vegetable tanning refers to leather that is tanned with oak
and spruce bark.

36. MATERIAL USED IN VEGETABLE TANNING:
2)Chestnut gives a hard and reddish leather.
3)Willow bark has 10% tannin and delivers yellow
wish leather.
1)Oak is suitable for all leather. Oak and spruce
bark from younger trees are used, because they
contain more tannin.

37. 1)TREATMENT WITH ORGANIC ACIDS:
The prepared skin/hide are treatment with organic acid to
neutralize any residual lines in drench vet.
2)TREATMENT WITH TANNING:
Tanning material fill the holes on skin and the weight of skin
increases.
acidic groups of vegetable tannins may combine with the basic
groups of the hide collagen by polyfunctional cross-linking via so-
called hydrogen bridges
STEPS OF VEHETABLE TANNED LEATHER:-

38. 1) CONDITION OF HIDE/SKIN
2) PARTICLE SIZE
3) ACID AND SALT CONTENT
4) TEMPERATURE
FACTORS RESPONSIBLE DURING VEGETABLE
TANNING PROCESS:

39. ADVANTAGES OF VEGETABLE TANNING
1)Used natural products so it is environmental friendly.
2)Unique products are formed.
3) The colors that vegetable tanning produces are rich and warm tones
that look completely natural
4) have very skilled craftsmen producing and dyeing the leather.
DISADVANTAGES:-
Time consuming process.
2)Expensive
3)Limited colors of leather produced
4)It is sensitive to heat (b/c it shrinks) and iron (cause stain).

40. USES OF VEGETABLE TANNED LEATHER

41. Chrome Tanning
Chromium Tanning, or chrome tanning, is
the most popular form of leather tanning
worldwide. The tanning agent that is used in
it, and for which it is named, is chromium
sulfate.

42. Process Of Chrome Tanning
• Pickling: to maintain the ph
• Treatment with sodium dichromate: it is a
chromium salt .
• One bath process:
• Two bath process:
• Treatment with borax: in which we maintain
desired ph
• Washing: to remove chemicals

43. Advantages or Disadvantages of
chrome tanning
• It produce soft lather
• Less expensive
• Quick and easy to produce
• It is heat resistant
• Unfriendly for environment
• No natural look appear

44. FINISHING PROCESS
Shaving process: for smoothness
Bleaching process: for add color
Dyeing process: dye the lather
Stuffing process: for shining
Spiliting process: to cut the lather
Glossing process: use glass clyender
Drying process: for dry the lather
Embossing process: for designing
Measuring process: measure the lather

45. Purpose For Finishing Process
Protect ammoniacl action
Labeling cut patches
Protect damaging effect
Modify surface property
Improve physical property

46. Importance of finishing process
• Produce flexible lather
• Produce shiny lather
• Color preservation
• Change the look

47. By Products
• Flash
• Trimming
• Beam

48. Uses of by products
• Use flash manufacturing of glue
• Use trimming manufacturing of protein
supplement
• Use beam manufacturing of tiles