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Файл:Processing Techniques for Different Furs. Tutorial
.pdf
The Ministry of Science and Higher Education of the Russian Federation
Kazan National Research Technological University
G. Lutfullina, V. Sysoev, E. Valeeva
PROCESSING TECHNIQUES
FOR DIFFERENT FURS
Tutorial
Kazan
KNRTU Press
2021
UDC 675.6(075)
Published by the decision of the Editorial Review Board
Lutfullina G.
Processing Techniques for Different Furs : tutorial / G. Lutfullina,
V. Sysoev, E. Valeeva; The Ministry of Education and Science of
the Russian Federation, Kazan National Research Technological University. – Kazan : KNRTU Press, 2021. – 108 p.
ISBN 978-5-7882-3081-8
ISBN 978-5-7882-3081-8
© G. Lutfullina, V. Sysoev, E. Valeeva, 2021
©
Kazan National Research Technological
University, 2021
UDC 675.6(075)
of the Kazan National Research Technological University
Reviewers:
Cand. Sc. (Technology) D. Semenov
Cand. Sc. (Philology) G. Mullakhmetova
This tutorial focuses on different types of fur raw materials, their processing
methods and technological operations using Russian and foreign chemical reagents.
The tutorial is intended for practical classes and lectures for training Bachelor’s degree students majoring in Technologies of Textile Industry. The study guide
can also be used for Doctoral and Master’s degree students conducting their research
in the field of fur and leather processing.
It has been developed at the Department of Plasma Chemistry and Nanotechnology of High Molecular Materials.
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CONTENTS
INTRODUCTION .............................................................................. 4
1. PROCESSING OPERATIONS FOR DIFFERENT TYPES
OF FUR RAW MATERIALS ............................................................ 5
1.1. Spring types of fur raw materials ................................................................... 5
1.1.1. Astrakhan wool ........................................................................................ 5
1.1.2. Merlushka lamb skins ............................................................................ 19
1.1.3. Fur sheepskins and wool sheepskins ..................................................... 20
1.2. Winter types of fur raw materials ................................................................. 43
1.2.1. Rabbit skins ........................................................................................... 43
1.2.2. Dog skins ............................................................................................... 51
1.3. Spring types of fur raw materials ................................................................. 52
1.3.1. Mole skins .............................................................................................. 53
1.3.2. Marmot skins ......................................................................................... 56
1.3.3. Large-toothed souslik skins ................................................................... 59
1.4. Winter types of fur raw materials ................................................................. 60
1.4.1. Muskrat skins ......................................................................................... 60
1.4.2. Squirrel skins ......................................................................................... 66
1.4.3. Mink skins .............................................................................................. 67
1.4.4. Marten skins .......................................................................................... 75
1.4.5. Arctic fox skins ...................................................................................... 76
1.5. Sea animal skins ........................................................................................... 82
1.5.1. Fur seal skins ........................................................................................ 82
1.5.2. Seal skins ............................................................................................... 84
2. PROCESSING OF FUR INDUSTRY WASTE ........................... 88
3. CHEMICALS FOR FUR AND LEATHER PROCESSING ....... 90
REFERENCES ............................................................................... 106
INTRODUCTION
Fur processing includes a large number of various chemical materials:
surfactants, antiseptics, enzyme preparations, tanning agents, acids, dyes and
other compounds. The total cost of chemical materials may be more than
50 % compared to the cost of processing certain types of fur. Generally,
the quality of the final product depends on the technological operations and
processes used for manufacturing semi-finished fur products, quality of
chemical materials, and technological equipment.
This study guide was created according to the experience of the leading
industrial companies of the fur industry. The study guide presents the research results of the Department of Plasma Technology and Nanotechnology
of High Molecular Weight Materials (Kazan National Research Technological University).
The study guide focuses on various fur raw materials, chemical and mechanical methods and technological schemes of their processing using Russian and foreign chemical reagents.
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1. PROCESSING OPERATIONS FOR DIFFERENT
TYPES OF FUR RAW MATERIALS
1.1. Spring types of fur raw materials
Spring types of fur raw materials include hides of horses, reindeer calfs,
fur slink calfs, reindeers, goats, and sheepskins. Sheepskins are subdivided
into astrakhan fur, lambskins, fur sheepskins, and woolskins. Spring types of
fur raw materials are sorted according to the specific Standards. These Standards do not divide skins of spring types into strains. The quality of the skin
is determined by its age-related variability and the defects of fur raw materials. Therefore, such properties as skin size, structural nature, density, height,
and color of the fur, thickness of the leather are taken into account to characterize the skins of agricultural animals killed at a certain age and having
approximately the same fur hair development.
The fur of the short-haired astrakhan skins and lambskins is curly-structured. The hair of sheepskins is ripple. The long hair hides have rod-hair
structure without curls.
Depending on the breed and age, several groups of sheepskins and woolskins are distinguished: skins of embryos, lambs and young animals, skins of
adult sheep.
1.1.1. Astrakhan wool
Astrakhan wool is made of lamb skins of purebred Persian sheep. Usually they are three days old. Astrakhan wool is distinguished by a peculiar
form of curls as well as silky and shiny hair. Persian sheep were bred on
the territory of modern Uzbekistan many centuries ago. Sheep of this breed
are well adapted to the desert conditions. The main producers of astrakhan
wool are Uzbekistan, Turkmenistan, Kazakhstan, Tajikistan, and Moldova.
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Depending on the age of the sheep, various types of fur and wool are ob-
tained: astrakhan wool, broadtail skins, beaver-lamb, and woolskins.
In the first days after birth, the hair of Persian lambs is curled. A hair
has a spiral shape, the axis of which is parallel to the surface of the skin.
Starting from the age of three days, the curls become looser and eventually
break into separate strands.
To sort astrakhan wool, the quality of its fur and skin, the quality of
preliminary processing and the skin size are determined.
To assess the quality of the fur, we should pay attention to its silkiness,
shine, density, type and size of the curl, as well as to the nature of the distribution of the pattern over the area of the skin. The hides are sorted according
to the hair softness. While the hair of some skins is soft and silky, other skins
have rough and tough structure. The astrakhan wool of the highest quality
has silky and soft hair.
The hair gloss is one of the main properties. It characterizes the quality
of astrakhan wool. Fur skins of the highest grades are distinguished by
a beautiful glossy shine. On the other hand, low-grade skins have matte or
low-sheen hair.
Purebred astrakhan beaver-lambs, astrakhan wool and broadtail skins
have a short hair, a wide tail at the base narrowed to the end with an appendage.
Preliminary processing. The skins of lambs are removed in a layer by
a long cut along the midline of the dewlap to maintain the area from the head
to the end of the tail and from the legs to the feet. The skins should be cleaned
of meat, fat, cartilage, dirt, and blood. They should be well defatted, straightened symmetrically without folds, and preserved by the dry-salted method
and pickling.
Astrakhan wool is sorted according to:
– the type;
– the method of preservation (dry-salted method, pickling);
– the skin thickness (up to 0.7 mm and more);
– the hair color (black, gray, brown, dapple, etc);
– by region of origin (Central Asian – Uzbek or Bukhara, Turkmen, Kazakh; European – Astrakhan, Moldavian, Ukrainian);
– by defects (without defects, with defects of the first group, with defects of the second group. It is allowed to combine skins without defects and
with defects of the first group in one batch). Low-grade skins are assembled
in separate batches. The batches are counted and weighed. A technical passport is issued for each batch. Each skin is marked using a needle punch.
A mark indicates the grade and type of a skin.
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Astrakhan skins and lambskins are characterized by the deep bedding of
the hair roots. The thickness of the papillary layer makes up most of
the thickness of the skin. In the thickness of the dermis, the fibers are located
almost parallel to the surface of the skin, close to one another and form a continuous mass at the border of the papillary and reticular layers. Skin collagen
fibers have a looped structure. The papillary layer is penetrated with hair
ends, that leads to the formation of a characteristic fracture on its surface
during peeling of the mesh layer. The hair height varies depending on
the topographic areas from 4.2 to 7.8 mm.
The weight of the curried skin is on average 275 g (preserved by
the fresh-dry method) and 325 g (preserved by pickling). The weight of
the skin as a semi-finished product is 225 g.
Application. Women's coats, short coats, jackets, women's and men's
hats and collars are made of astrakhan skins.
Sorting. Purebred astrakhan skins are sorted according to GOST 9296-74.
They are divided according to the fur quality: various degrees of silkiness
and shine, consisting of curls of various shapes, covering the entire area of
the skin; the neck is covered with curls with a straightened hair length of no
more than 30 mm; the fur of the head and paws has a special pattern or curls;
on the hind legs, below the hock joint, smooth hair is allowed; the tail is wide
at the base, narrowed towards the end, covered with elastic or loose spreading
curls.
The skins should be removed in a layer saving all parts, symmetrically
straightened with a tightening to the width, with the paws spread out to
the width. The fur should be clean, uniformly colored deep black. The skin
should be soft, clean, uniformly and evenly colored blue or dark blue, and
stretch in all directions. Tears, crowbars, holes, bald patches, worn-out places
must be removed without breaking the symmetry of the skin. Inserts and attachments are selected in accordance with the curl shape, fur quality and skin
color. Skins selected for industrial processing are not repaired, but the tears
on them should be sewn up.
Astrakhan skins are sorted by size: large, medium, small, extra small.
In addition, the shape and size of the curls are taken into account.
The purebred dyed skins, depending on the quality of the fur and
the shape of the curls, are divided into 26 grades, including large and medium-sized skins. Depending on the defects, purebred skins are divided into
four groups.
Purebred gray undyed skins are sorted according to GOST 3157-69.
Purebred dyed skins are sorted according to GOST 3595-74.
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Marking. Digital code is applied on a skin. It indicates the skin size
(large – 1, medium – 2, small – 3. extra small – 4); grades; groups of defects;
the skin area is expressed in dm
2
.
Processing of Astrakhan skins. According to the Standard Technology
developed for Astrakhan skins, their processing starts with the operation of
soaking, which depends on the method of preservation. To preserve skins by
fermentation, the process of soaking is carried out in solutions of sodium
chloride (30.0 g/dm
3
) and acetic acid (1.5 g/dm3). Alums (kvass) of the required acidity obtained after fermentation is also used instead of acetic acid.
In case of hair slipping, zinc chloride is added to the bath, and the acidity is
increased to 4.0 g/dm
Flint-dried skins are processed for 10–12 hours at 25 ºС in a solution of sodium chloride (20.0 g/dm
3
(process duration – 8–10 hours, temperature – 30 ºС).
3
) and zinc chloride (1.0 g/dm3).
After fleshing, the skins are translucent on a glass table with with a lighting fixture placed under the glass. This procedure allows us to identify skins
with fractures of the epidermis and papillary layer. The skins with fractures
are sorted into separate batches, which are not subjected to pickling.
Souring is used to process fur raw materials using bread kvass. This is
one of the oldest methods of fur dressing. The method of pickling has narrowed the scope of souring application significantly.
One of the most important characteristic of souring is softening. Fermentation provides high softness and ductility, and mechanical strength of
the skin, while maintaining the size, reducing the thickness and weight of
the skin. In addition, it reduces skin cracking and delamination. During fermentation, the microstructure of skin changes. The intertwining collagen
bundles are separated into smaller structural elements during the process of
pickling. The loosening of raw materials with a simple structure of skin is
noticeable, when the bundles consist of fibrils. A more complex structure of
the skin (fibrils-fibers-bundles) does not provide the deep fiber separation.
Crushed grain and flour (oatmeal, barley flour) are used as initial materials for souring. During the process of softening, flour, malt sprouts, and bran
are used. To protect the skin from acid grease, the composition of the fermentation and softening solutions includes a neutral salt (sodium chloride).
Souring is used only for processing purebred Astrakhan skins after
the dry-salted method. This process is characterized by a fine separation of
fibers of the dermis. Softening is used to process lamb and goat skins.
At the beginning of soaring, a fermented solution is prepared. Flour is
stirred with water (110 g/dm
3
) at 40–42 ºС and kept for a day in a special
vessel. Then the solution is pumped into a drum and diluted with water until
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the acidity of the solution is 3–4 g/dm3 (in the presence of acetic acid). Then,
sodium chloride (60 g/dm
processed for 5-6 days. The acidity of the ferrous solution increases up to
10–12 g/dm
3
by the end of the process.
3
) is added. The skins are loaded in the drum and
Souring is a complex biochemical process, as a result of which the composition of the fermentation solution is constantly changing. Flour and grains
contain starch, sugars, proteins, enzymes, and fibers. The process depends
on starch and enzymes. There are two types of enzymes. The first type relates
to degrading (saccharifying) enzymes. The second type refers to proteolytic
carbohydrates, which provide the accumulation of sugars and acids, as well
as the contamination of grain by microorganisms.
Starch is the initial product from which organic acids are formed during
the process of souring. It is insoluble in cold water. However, an increase in
the temperature of water leads to its swelling. It forms a colloidal solution
(paste) at 55–80 ºС. 10 % of starch is gelatinized at 50 ºС, and about 90 % of
starch is gelatinized at 60 ºС. The paste provides the formation of sugars from
it by the action of enzymes. Non-gelatinized starch is practically not saccharified. However, the temperature of the fermentation solution is insufficient
for starch gelatinization, and the bulk of organic acids is formed from simpler
carbohydrates.
Thus, starch, which makes up most of the flour, is used inefficient. Although, it can be assumed that part of the starch is gelatinized due to the long
period of the process in an acidic medium,
Enzymes hydrolyze starch and form sugars (maltose and glucose),
which are the material for the formation of organic acids as a result of fermentation caused by acid-forming flora. Fermentation is a type of enzymatic
process in which enzymes are produced as a result of the vital activity of
bacteria, yeast and mold.
Acids of a fermented solution are produced by lactic acid bacteria,
the optimum effect of which is observed at 32 ºС. They ferment glucose and
maltose with the formation of mainly lactic acid (up to 70 % of the total
amount). Acetic, formic and butyric acids are the by-products of the process.
After 4–6 hours from the moment of preparation of the solution, the development of putrefactive and butyric acid bacteria is prevented by the acidity
of the environment. Foreign cultures growth is inhibited in an acidic environment, and the development of lactic acid microflora is stimulated.
The process of stirring inhibits the development of anaerobic bacteria.
The use of the same vessels containing spent solutions as a ferment to prepare working solutions also inhibits the growth of foreign bacteria.
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The souring scheme:
!Organic acids
Starch → Maltose → Glucose
"
Gaseous products
The possible release of gases in the first hours of acidification of working
solutions is explained by the vital activity of yeast or mucus bacteria. Then,
the formation of gases stops as a result of the rapid growth of lactic acid microflora. Therefore, the release of gases (especially at the final stage of fermentation), as well as the possible release of hydrogen, indicates that the process is proceeding under the wrong conditions. This may be associated, for
example, with the development of butyric acid microflora. In this case, microorganisms do not affect the fur skin as they form only organic acids.
Plant proteolytic enzymes (papain and bromelin) act on collagen and
gelatin, breaking various bonds in the protein particle. This leads to a significant separation of the microstructure of the dermis, which determines
the high plastic properties of the final fur skin.
As a result of the fermentation reaction, a reducing medium is created
in a fermentation solution, which is equivalent to the medium created by
a 0.2 % solution of hydrosulfite, one of the most powerful reducing agents.
This environment increases the activity of flour proteolytic enzymes. In addition, reducing agents loosen the proteins in the hide, including reticulin
fibers.
Thus, there are two main effects of the souring process. They are:
• proteolytic effect of plant enzymes (dominant factor);
• pickling effect (organic acids and sodium chloride form organi
pickel).
Factors affecting the souring (fermentation) process:
1) Acidity of the process. The pH of the fermentation bath influences
the proteolytic activity of enzymes. The optimum value is about 7 (neutral or
slightly acidic environment). As the acid accumulates and the pH decreases,
the activity of these enzymes decreases.
2) Temperature of the process. Temperature is one of the most important
parameters of the process. It influences both the enzyme activity and the development intensity of the microflora. The optimum temperature for the development of lactic acid microflora is 37–40 °C.
c
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