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Файл:Processing Techniques for Different Furs. Tutorial
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11
3) Duration of the process. An increase in the processing time leads to
significant changes in the skin microstructure, while the strength of the connection between the hair and the dermis decreases. Duration of the process
depends on the type of skins and the technology used.
4) Sodium chloride. It is used to provide swelling in the presence o
organic acids. It practically has no effect on enzymatic and microbiological
processes.
Therefore, during souring (fermentation, softening), the accumulation
of acid in the solution, pH, sodium chloride content, solution temperature,
and sourness of the skins are controlled.
The quality of the skins after souring is checked organoleptically and
histologically by its looseness and plasticity.
The color of the flesh side of the finished skins is to be light.
Damage to the hair follicles, causing weakening of the hair-skin bond
in the groin areas of the hide, is a sign of sourness of the hides. If we detect
hair slipping by slight rubbing with fingers and weak pressure on other parts
of the skin, the process should be stopped immediately.
After the process of souring, the ageing of hides is unacceptable, as it
may lead to hair slipping.
Bating. In order to save food materials, the processes of souring and
pickling are combined. It is called bating. Firstly, the skins are processed in
freshly prepared fermentation solutions with low acidity (1 g/dm
3
in terms of
acetic acid). Then, acetic or sulfuric acid is added to start the process of pickling. At the first stage, favorable conditions are created for the action of enzymes that contribute to the dissociation of the structure and the production
of soft skins. At the second stage, as the acidity of the solution decreases,
the action of enzymes is inhibited or completely stopped.
Compared to souring, the process of bating may lead to hair slipping at
the first stage as a result of the rapid growth of enzymatic action. In this case,
the addition of mineral acid is required to lower the pH and slow down the action of enzymes. In addition, due to the lack of a stable lactic acid microflora
in the softening solution, extraneous putrefactive bacteria may develop. Therefore, the use of antiseptics is recommended during the process of bating.
Before the operations of souring or bating start, the hides are to be
checked and sorted carefully. The weakening of the connection between
the hair and skin resulting from the hidden defects or bacterially infections
of raw materials, may lead to the additional defects of the hides during
the preparatory processes.
f
12
Ways to replace the process of souring. There are some disadvantages
of the souring process. They are:
• a long time of the process;
• the use of food products;
• incomplete saccharification of starch;
• the difficulty of process control;
• fermentation defects;
• the lack of objective control methods.
These disadvantages make us look for more economically and chemi-
cally effective processing methods.
Enzymatic bating. Nowadays, enzymes are widely used inthe fur industry. Enzymes of the carbohydrase series of maltavamorin P2x or G10x
(a complex mucolytic enzyme) is one of the most popular for fur processing.
The complex enzyme contains several enzymes, each of which is characterized by its optimum action at a certain pH and temperature. By changing
these parameters, you can inactivate individual enzymes and increase the activity of others. Pectolytic preparations (pectoavomorin P10x, pectofoetidin
P10x) have also been tested and recommended.
The process of enzymatic bating is performed according to the following scheme: pre-pickling - bating - pickling.
Pre-pickling is used to prepare the skin for bating. It is carried out in
the presence of acetic acid (1.5 g/dm
3
) at a solution temperature of 38 °C and
pH 4.5–5. During the process, the proteinase capacity decreases, and the disruption of the hair-skin bond is not observed. Within 4–5 hours, the skin fibers partially separate from each other, as a result of dispersion and washing
out of carbohydrates.
The stage of bating is the most important one. This process aims at removing mucopolysaccharides and loosening the fibrous structure of skin.
The process is performed in the presence of enzymes. The duration of
the stage is 8–16 hours (pH – 4.5, temperature – 38 ºС). The processing duration and enzyme concentration depend on the type of processed raw materials. It is carried out in the presence of an antiseptic and sodium chloride.
The next stage of pickling is performed in a solution of sulfuric acid and
sodium chloride. The process aims at fixing the loosened structure as a result
of dehydration of skin and creating favorable conditions for subsequent tanning. Pickling can be carried out in the presence of a mixture of sulfuric and
organic acids.
Enzymatic bating can be combined with tanning and greasing processes.
13
Batch pickling. The process is carried out with a gradual increase in
the acidity of the bath from 1 to 8 g/dm
3
. This mode is used to provide high
plastic properties of the skin. In addition, it does not weaken the connection of
the hair with the dermis. The degree of fiber separation is almost the same as
when souring. Therefore, in some cases, souring is replaced by batch pickling.
Next, the tanning process is carried out. One of the factors that determine the rate of diffusion of tanning compounds into the dermis and hair is
the degree of preliminary separation of structural elements and collagen
opening. This factor is one of the most important ones for tanning fur skins,
since the presence of the epidermis prevents the diffusion of tanning substances from the papillary layer, which may lead to an uneven distribution of
the tanning agent. For the same reason, the basicity of the chrome tanning
agent used for dressing fur should be low. An excessive increase in basicity
can lead to a sharp increase in tanning particles (olification) as well as to
a slowdown in their diffusion. If the prelimenary processes include souring
or pickling with organic acids, the basicity should be lower than for pickling
with sulfuric acid.
Tanning. Tanning of astrakhan fur skins is carried out under mild conditions to prevent the loss of plastic properties of the skin. During the process
of tanning, a chrome extract is used, the basicity of which is 15 % based on
the chromium oxide content of 0.9 g/dm
ature is not reached (not lower than 60 °C) after 8 hours of the treatment in
the chromium extract solution, soda is added at the rate of 0.5 g/dm
3
. If the required shrinkage temper-
3
As the pH rises, the binding of chromium compounds to collagen increases.
The process of tanning lasts 10 hours at a temperature of 30 °С and float rate
of 10.
Fur skins are refleshed after the processes of tanning, ageing, samming,
and stacking.
Greasing. The process of greasing is carried out by spreading various
fat emulsions on the surface of the skin. Nowadays, there are different methods of greasing combined with tanning.
For Astrakhan fur, the following technology is recommended. Water
and sodium chloride is mixed in the bath for greasing. Sodium chloride is
used to exclude grease, which complicates the process of diffusion and leads
to uneven tanning. Then the skins are loaded into the bath. After 10 minutes
the Tetrapol preparation and Coripol peltsliker are added to the bath. Chromopol is used as an oiling agent. After 2 hours, chrome tanning agent with
basicity of 35–40 % is added to the bath and the skins are processed for 14–
16 hours. Then the pH of the bath is checked. If the pH of the bath is low, it
.
14
is gradually risen to 3.6 using sodium carbonate solution and the process is
continued for 2 hours. This is followed by ageing for 24 hours and samming
in a centrifuge.
After the processes of tanning and greasing, finishing operations are fol-
lowed.
Finishing operations. Finishing operations include the sequential processes: stacking – drying – ageing – first drumming – stacking – drying –
second rolling – stacking – cleaning. Astrakhan skins have a specific structure which requires certain operations to avoid defects, in particular,
the crackling of the face side. For example, a high temperature of drying results in crackling. Typically, drying temperature is 40 °С, relative humidity
is 43 %. After drying, the skins are sorted and dyed.
The acid dyeing temperature is high. Therefore, the shrinkage temperature of the skin is to be at least 90 °C. This value is achieved by the process
of retanning. This process is carried out at 40 °C for 2 hours. The retanning
solution contains 40 g/dm
agent; 0.5 g/dm
3
of sodium carbonate. After 2 hours, the pH value of the bath
3
of sodium chloride; 1.0 g/dm3 of chrome tanning
should not be lower than 3.8–3.9 and the shrinkage temperature should not
be lower than 90 °C. Otherwise, sodium carbonate is added and the process
is continued until the required shrinkage temperature is reached.
The process of neutralization is carried out for an hour before dyeing.
The neutralization temperature is 35–42 °C. The process is performed in
the presence of sodium carbonate with a concentration of 1.0–2.0 g/dm
noethanolamide (1.0 g/dm
3
) or Peramite ML (2.0 g/dm3) may be used as sur-
3
. Mo-
factants for uniform neutralization. Then, the skins are rinsed with clean water. Two rinses are usually used. Each rinse takes 30 minutes.
After neutralization, the process of dyeing is followed. The dye solution
contains 2.0–4.0 g/dm
5.0 g/dm
3
of neutral salt and 2.5 –5 cm3/dm3 of acetic or formic acid to main-
3
of dissolved dyes, 0.5–1.0 g/dm3 of leveler, 3.0–
tain the pH at 2.8–3.0. The duration of dyeing is 2–3 hours.
The technology developed in Melita (Russian fur manufacturing company) is presented below.
Water and dissolved Level A are poured into the dyeing bath. Then,
the skins are loaded in the bath. After 15 minutes, dyes are added to the bath
in the ratio of 1 volume of a dye to 5 volumes of water. Alizarin dyes are
used as acid dyes. After 30 minutes, the first portion of formic acid (diluted
in water in the ration 5:1) is added to the bath. After 30 minutes, the second
portion of formic acid is added. Then, the solution is drained out. After
30 minutes, the last portion of the acid is added. After dyeing, the skins are
15
washed in a solution containing a nonionic surfactant and cleaned with water.
Then, the processes of souring and greasing are carried out. Finally, a complex of finishing operations is performed.
Russian Research Institute of Fur Industry recommends the following
technology for processing dry-salted Astrakhan skins. All processes in liquid
solutions at the preliminary and tanning-greasing stages are carried out at
a float rate of 8.
The first soaking takes about 2 hours at 30–33 ºС. The soaking solution
contains Effect M (1.0 g/dm
carried out at the same temperature, but the process duration increases to 8–
16 hours. The soaking solution contains sodium chloride (20.0 g/dm
Gamma 1 (2.0–3.0 g/dm
(1.0 g/dm
3
).
3
) and FKh (0.5 g/dm3). The second soaking is
3
), Gamma 3 (1.0 g/dm3), and a preparation
3
),
After soaking, the operation of fleshing is performed. This is followed
by the pickling process at a temperature of 35–38 ºС for 30–48 hours.
The pickling solution contains sodium chloride (40.0
(1.0 g/dm
3
), lactic acid (4.0–5.0 g/dm3), and formic acid (2.02 g/dm3). Lactic
g/dm
3
), Gamma 2
acid is added to the solution after two hours of dosing the first two reagents.
Formic acid is added to the solution after three hours of dosing of lactic acid.
After the process of ageing, the tanning-greasing process is carried out
at 38 ºС for 6–8 hours. The composition of the bath is sodium chloride
(35.0 g/dm
of the process, a chrome tanning agent (2.2–4.8 g/dm
12.0 g/dm
3
), Gamma 3 (1.0 g/dm3), hyposulfite (10.0 g/dm3). After 1 hour
3
) are added to the solution.
3
) and Mexinol (10.0–
After the subsequent process of ageing (12–24 hours), the operations of
samming, drying, and drumming are carried out. The operations are performed for 3.5 hours using wet sawdust with the addition of Gamma 6 (8.0–
10% of the weight of the skins).
Then, the operations of dyeing and greasing are performed. Typically,
the skins of gray Persian lambs are processed in a following way. Since
the dyeing is performed by acid dyes, the process of retanning is carried out
for 6–8 hours at a float rate of 15 and at a temperature of 35 ºС. The composition of the bath solution is sodium chloride (40.0 g/dm
agent (8.0 g/dm
3
), sodium bicarbonate (0.5–1.0 g/dm3) at a pH of 3.6–3.8.
3
), chrome tanning
After the process of retanning, the shrinkage temperature is not less than
80 ºС. Then, the operation of samming is carried out. After that, two operations of washing are performed at a float rate of 15 and at a temperature of
35 ºС. The first washing is performed for 1.0–1.5 hours with the addition of
16
Effect M (1.0 g/dm3). The second washing is carried out with clean water for
30 minutes.
After the operations of samming and shaking, the skins are dyed for
2.5 hours at a float rate of 15 and at 60 ºС. The composition of the dyeing
bath is a leveler (1.0 g/dm3), acid dyes for fur (each color has its own composition), acetic or formic acid (2.0–2.5 g/dm3) .
Then, two washes are carried out: the first one is performed for 0.5 hour
with the addition of Effect M (0.5 g/dm3) at 32 ºС, the second one is performed with pure water (the process parameters are the same). After the operations of washing, the skins are salted and greased. These operations are
performed for 3 hours at a float rate of 15 and at 35 ºС. The composition of
the working solution is sodium chloride (20.0 g/dm3) and Mexinol
(3.0 g/dm3). Finally, the finishing operations are carried out.
Joseph H Lowenstein & Sons Inc has developed the following technology for the processing of dry-salted astrakhan skins. The float rate for all
processes conducted in liquid solutions is 8. The skin preparation begins with
the operation of soaking at 30 ºС. The operaration takes 14–16 hours.
The working solution contains sodium chloride (20.0 g/dm3); Wetter HAC
(1.0 g/dm3); Elbro 100-C (2.0 g/dm3). After that, the skins are refleshed if it
is necessary. For dirty and hard-to-soak skins, the operation of washing is
carried out for 2 hours at 32 ºС. The operation proceeds with the addition of
sodium chloride (40.0 g/dm3); Wetter HAC (1.0 g/dm3); De-Sol-A
(2.0 g/dm3). Then, the skins are cleaned with water and fleshed.
The process of pickling is carried out for 16–18 hours at 32 ºС.
The composition of the pickling bath is sodium chloride (50.0 g/dm3); Wetter
Hac (1.0 g/dm3). After 30 minutes, Super Lotan A (3.0 g/dm3) is dosed. After
3 hours, formic acid (3.0 g/dm3) is added. After 30 minutes, Tanning Oil G
(2.0 g/dm3) is added. Next, the solution is drained, and the skins are ageing
for 10-12 hours (overnight).
The next process is tanning, which is performed at 35 ºС for 16–
18 hours. The working solution contains sodium chloride (50.0 g/dm3); aluminum alum (25.0 g/dm3). After 2 hours, a dry chrome tanning agent Cr2O3
(1.5 g/dm3) is dosed. After 1 hour, dissolved Tan Ly (2.5 g/dm3) is added.
After 1 hour, Tanning dissolved Assist B is added in two doses with an interval of 1 hour (in the amount of 1.5 and 2.0 g/dm3, respectively). After
1 hour, Tanning Oil G (2.0 g/dm3) and Nu Oil (1.0 g/dm3) are added. After
tanning, the semi-finished fur product is sammed and sent to the stage of
greasing. Chemical reagents for greasing are Nu Oil – 1 part, Tanning
17
Oil G – 1 part, water – 4 parts. Next, the semi-finished product is ageing for
2 hours. If necessary, the operations of greasing and ageing are repeated.
Next, the semi-finished product is dried and sent to the stage of drumming. The operation of drumming is performed for an hour with the addition
of 10 dm
3
of water per bag of sawdust. After drumming, the operations of
shaking, staking, drying, and chemical cleaning (2.5 minutes) are carried out.
Then the operation of drumming is repeated. It is performed for an hour with
the addition of 10 dm
3
of water per bag of sawdust. Then the operations of
shaking, staking, drying are conducted again. Finally, the operation of drumming is carried out with the addition of Drumming Solvent 14. It lasts for
3 hours. The operations of shaking and stacking finalize the stage.
Pulkra (Boehme) company has proposed the technology for curring of
astrakhan skins, preserved by souring. All processes in liquid solution are
carried out at a float rate of 15. Firstly, raw materials are sent to the stage of
soaking (temperature – 25 ºС, duration – 16–18 hours). The composition of
the soaking bath is Atezan LPV (2.0 g/dm
formalin (0.2 g/dm
3
); Coratil BLN (1.5 g/dm3). Caratil BLN is dosed 1 hour
3
); Foryl PC (1.5 g/dm3); 25 %
after loading all reagents.
After fleshing, washing is carried out at 34 ºС for 1.5–2 hours. The composition of the washing bath is Atezan LPV (1.0 g/dm
(2.0 g/dm
3
); sodium carbonate (0.5 g/dm3, dosed after 1 hour). Then, raw
3);
Foryl PK
materials are rinsed in clean water, and the skins are sent to the stage of pickling (temperature – 30 ºС, duration – 16–18 hours). The pickling solution
contains sodium chloride (60.0 g/dm
(0.5 g/dm
3
) is added. After 30 minutes, glycolic acid (6.0 g/dm3) is dosed.
After an hour, 85 % formic acid (6.0 g/dm
after 30 minutes, Tannit AGS (3.0 g/dm
3).
After 30 minutes, Foryl PK
3
) is added to the solution. Finally,
3
) and Eskatan GLS (3.0 g/dm3) are
added to the solution.
After the process of pickling the PH value should range between 2.6 and
2.8. Next, the skins are sent to the stage of ageing for 1–5 days.
Then, the skins
a temperature of 35 ºС for 16–18 hours. The working solution contains sodium chloride (50.0 g/dm
to the solution. After 30 minutes, formalin (1.0 g/dm
1.5 hour of rotation, chrome tanning agent (3.0 g/dm
(Pellan FSN – 7.0 g/dm
are slicked. After that, they are tanned and greased at
3
). After an hour, Tannit AGS (5.0 g/dm3) is added,
3
, Pellan GLH – 5.0 g/dm3, Pellan GLS – 4.0 g/dm3)
3
) is added. After
3
, 33 % basicity); fats
are added to the solution. After 2 hours, sodium bicarbonate (0.5–1.5 g/dm3)
is dosed. pH at the end of tanning ranges between 3.6 and 3.8.
18
Next, the skins are ageing for 1–2 days. Then, they are sent to the stages
of drying and degreasing with perchlorethylene (in the ratio of 6–8 cm
Macrol SES to 1 dm
3
of perchlorethylene) for 2 minutes. After drying, wet
3
of
drumming is carried out for 2 hours in the presence of Kutafix LGF (3.0 dm
per 100 kg of wet sawdust).
Acid dyeing is used in the proposed technology.
The semi-finished products are shaken and sent to the retanning process
at a temperature of 35 ºС for 2 hours. The composition of the bath is sodium
chloride (30.0 g/dm
mium salt (33 % basicity, 2.0 g/dm
are loaded into the solution. After an hour from the beginning of retanning,
sodium carbonate is dosed (1 g/dm
3
); Foryl PC (0.5 g/dm3); formic acid (0.5 g/dm3); chro-
3
); 30 % formalin (6.0 g/dm3). The skins
3
, pH 3.7–3.8).
Then, the skins are sammed and sent to the process of neutralization at
a temperature of 35 ºС for 2 hours. The composition of the bath is sodium
chloride (20.0 g/dm
carbonate (2.0 g/dm
drummingand and neutralization are carried out. The latter takes place at
a temperature of 30 ºС for 1 hour in the presence of 1 g/dm
3
); Foryl PK (0.5 g/dm3); Kutafix A (2.0 g/dm3); sodium
3
); 25% ammonia (2.0 g/dm3). Then the operations of
3
of acetic acid
(65 %). Then, the process of drumming is repeated. After that, the skins are
sent to the stage of pickling at a temperature of 30 °C for 0–12 hours.
The composition of the bath is sodium chloride (20.0 g/dm
(0.5 g/dm
are loaded into the prepared solution. After an hour, hexavalent chromium
(2.0 g/dm
3
); 65 % acetic acid (0.5 g/dm3); Softymol A (2.0 g/dm3). The skins
3
) is added to the solution.
3
); Foryl PC
Then, the semi-finished products are sent for dyeing with oxidation dyes
produced by Pulkra (Boehme) – Dorapel Fast. Hair dyeing is carried out at
a temperature of 35 ºС for 6 hours. The composition of the dyeing bath is predissolved dye Dorapel Fast (x g/dm
(1.0 g/dm
3
); 30 % hydrogen peroxide (3.0 g/dm3). The skins are loaded into
the bath. After 5–6 hours, a second portion of hydrogen peroxide (3.0 g/dm
3
); Kutafix A (3.0 g/dm3); 25 % ammonia
3
is added.
After dyeing, the skins are rinsed and sent to the stage of samming and
greasing. Greasing is performed in the solution bath at 35 ºС for 2 hours in
the presence of sodium chloride (20.0 g/dm
GLS (2.0 g/dm
for 3–6 hours (in the ration of 2 dm
3
). After samming, the operation of drumming is carried out
3
3
); Pellan FSN (5.0 g/dm3); Pellan
of Kutafix A to 100 kg of old sawdust).
Next, the semi-finished products are shaken, dried and sent for weighing,
sorting, and marking.
3
)
19
1.1.2. Merlushka lamb skins
Merlushka lamb skins differ both in the thickness of the skin and in
the nature of the hair. These skins are produced in natural form and dyed
black and brown.
Application. Lamb skins are used to make headdresses, collars, women's fur coats, jackets, children's coats, gloves. The skins should be dressed
in a layer while maintaining their configuration and symmetrically straightened. Merlushka lamb skins are dyed and cut. The cutting height ranges drom
8 to 18 mm.
Sorting. Lamb skins are sorted according to GOST 21184-75 and subdivided according to types, varieties and groups of defects. Unshorn and
sheared skins, depending on the quality of the hair, are divided into various
types. According to the groups of defects, the dressed skins of lambs are divided into four groups.
Marking. Numerical designations of the type, grade, and group of de-
fects are applied on the surface of each skin. The numerical designationarea
of the skin area in dm
2
is applied separately on the rump.
Technology of lamb skin processing. The main processing operations
of lamb skins are softening and picking. For softening effect, proteolytic enzymes are used in a weakly acidic environment (pH 5–6). Therefore, it is
recommended to separate the softening action and pickling by adding acid
after loosening of the skin. The histological analysis showed that the skins
processed by softening and then pickling had a soft skin with good elastic
properties.
There are three main tekhniques of softening and pickling:
1. Softening and pickling are carried out for 48 hours at 38 ºС in a bath
containing oat flour, table salt and acetic acid. Sodium chloride and oat flour
are dissolved in water. Then, the skins are loaded into the solution and leave
for 36 hours. After that, sodium chloride is added to its content of 50 g/dm
3
Then, acetic acid is added. The duration of the process is 12 hours.
2. The process of softening is carried out in the presence of malt sprouts
(40 g/dm
3
), which contain a large amount of proteolytic enzymes. The process proceeds for a day. After softening, the appropriate amount of salt and
acid is added to the solution bath. Then the process of pickling is carried out.
3. Batch pickling aims at treating the skins in the solutions of sodium
chloride and acid, gradually increasing the acidity. To increase the acidity
gradually, the required amount of acid is added in several stages. The stage
.
20
of pickling lasts three days at 38 ºС. Then, the skins are loaded into the bath.
The concentration of sodium chloride is 50 g/dm
acid is 3 g/dm
to the concentration of 8 g/dm
acid is increased to 10 g/dm
3
. After 24 hours, the acidity is increased by adding acetic acid
3
. After 48 hours, the concentration of acetic
3
. At the same time, oat flour (25 g/dm3) is added
3
, the concentration of acetic
to the solution to intensify the process of fleshing due to the creation of some
roughness of the skin surface. The skins are treated in this solution for
72 hours.
Subsequent operations are carried out in the same way as operations for
astrakhan skin processing. The treatment with a steam-air mixture is used to
shorten the production cycle and reduce the consumption of sawdust instead
of the first drumming. During the treatment, the relative air humidity is 98 %,
the temperature inside the drum is 40–45 ºС.
1.1.3. Fur sheepskins and wool sheepskins
Sheepskins are produced in all breeding areas of fine-fleece, semi-finefleece, semi-coarse-wool breeds of sheep.
The term "fur sheepskin" refers to the skins of sheep of fine-wooled,
semi-fine-wooled, semi-coarse-wooled breeds of different types of crossbreeding, age and sex of animals. The term "sheepskin" refers to the skins of
sheep of coarse-wooled breeds. There are also steppe and Russian sheepskins. The steppe sheepskins relate to fat-tailed and karakul breeds. The skins
of sheep of all other coarse-wooled breeds (except for the Romanov one,
which are separated into an independent group) are referred to the Russian
sheepskin.
Sheepskin, unlike fur sheepskin, has a braided hair structure. The quality of sheepskin hair depends on the breed, the age of the sheep, the season
of slaughter, the conditions of keeping the animals, defects and the primary
processing of the sheepskins.
The quality of sheepskins is determined by the quality of the hair, since
it is primarily exposed to external influences, as well as the quality of
the skin, which determines the strength of the product. The hair is considered
as uniform, if it consists of hair of the same category (downy, transitional,
guard, etc.). The degree of uniformity is determined by the ratio of hair
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