ArticlePDF Available

Abstract and Figures

Chromium tannage is the most used technology in processing of garment leathers. Due to environmental requirements and demands on natural products there is an increasing interest on alternatives to chromium tannage especially on vegetable tanned leathers. Leather properties vary in a very wide range depending on the animal type it is obtained from and the process type and chemicals used in the manufacturing. In this study, the effect of various tanning materials to the sewability of garment leathers was investigated. For this purpose, vegetable, chromium and chromium-vegetable combination tanned garment leathers from the same animal origin were supplied from a garment leather manufacturing factory. Needle penetration force and the sewability values of these leathers were determined by using L&M Sewability Tester. It was found that material properties and sewing properties showed differences regarding to the tanning material used even in same type of raw material. Chromium tanned leathers had sewability values of 13.4% horizontal and 14.2% vertical which are considered good to fair. Vegetable tanned leathers and chromium-vegetable tanned leathers had sewability values of 38.2% horizontal, 49.2% vertical and 98% horizontal, 98.5% vertical respectively which are considered poor. The results of the study conclude that, there is a big difference in material properties when the tanning technology and material is changed which also affects the sewing properties.
Content may be subject to copyright.
ANNALS OF THE UNIVERSITY OF ORADEA
FASCICLE OF TEXTILES, LEATHERWORK
197
SEWABILITY PROPERTIES OF GARMENT LEATHERS TANNED
WITH VARIOUS TANNING MATERIALS
ORK Nilay1, MUTLU Mehmet Mete1, YILDIZ Esra Zeynep2, PAMUK Oktay3
1 Ege University, Faculty of Engineering, Leather Engineering Department, 35100, Izmir, Turkiye, mete.mutlu@ege.edu.tr
2 Ege University, Emel Akin Vocational Training School, 35100, Izmir, Turkiye, esra.zeynep.yildiz@ege.edu.tr
3 Ege University, Faculty of Engineering, Textile Engineering Department, 35100, Izmir, Turkiye,
oktay.pamuk@ege.edu.tr
Corresponding author: Yildiz, Esra Zeynep, esra.zeynep.yildiz@ege.edu.tr
Abstract: Chromium tannage is the most used technology in processing of garment leathers. Due to
environmental requirements and demands on natural products there is an increasing interest on alternatives to
chromium tannage especially on vegetable tanned leathers. Leather properties vary in a very wide range
depending on the animal type it is obtained from and the process type and chemicals used in the
manufacturing. In this study, the effect of various tanning materials to the sewability of garment leathers was
investigated. For this purpose, vegetable, chromium and chromium-vegetable combination tanned garment
leathers from the same animal origin were supplied from a garment leather manufacturing factory. Needle
penetration force and the sewability values of these leathers were determined by using L&M Sewability Tester.
It was found that material properties and sewing properties showed differences regarding to the tanning
material used even in same type of raw material. Chromium tanned leathers had sewability values of 13.4%
horizontal and 14.2% vertical which are considered good to fair. Vegetable tanned leathers and chromium-
vegetable tanned leathers had sewability values of 38.2% horizontal, 49.2% vertical and 98% horizontal,
98.5% vertical respectively which are considered poor. The results of the study conclude that, there is a big
difference in material properties when the tanning technology and material is changed which also affects the
sewing properties.
Key words: Leather, Sewability, Garment, Tanning materials.
1. INTRODUCTION
Leather processing can simply be defined as, modification of hides/skins by a sequence of
chemical and physical treatments. Although leather processes and the preferred chemicals have big
contribution to designation of final leather characteristics, the type of the raw material, type and
amount of tanning material used, have the most important effect [1]. Modern tanning chemistry can
be classified by mineral, vegetable, oil, aldehyde, and organic tanning and syntans [2].
Chrome tanning is one of the most popular tanning systems because of the excellent
qualities of chrome tanned leather such as high hydrothermal stability, good dyeing characteristics
and softness [3]. Although vegetable tanning materials are generally used in production of saddlery,
harness, belt, shoe upper and sole leathers requiring less elasticity, high shape retention and
firmness; their use in garment leather production has increased due to natural look and feel they
ANNALS OF THE UNIVERSITY OF ORADEA
FASCICLE OF TEXTILES, LEATHERWORK
198
confer to leathers and high demands on natural products in last decades. The vegetable tanning
process is flexible, and can produce leathers with a very wide range of characteristics [4]. Besides,
combination of various tanning materials and chemicals provide a possibility to combine their
characteristics or even to enhance properties with their synergistic effect. This can lead to produce
leathers with better properties than the leathers tanned with a single type of tanning material.
Leather clothing differs in its origin, tannage and mechanical or physical properties. It is
necessary to distinguish between pig, goat and sheep leather, and cowhide, which differ both in their
properties and in their surface appearance. Leather clothing is affected both by its basic mechanical
properties and usage characteristics and by the manufacturing features of the leather [5].
Apparel making is the process of making shell structures from flat fabrics or leathers to
match the shape of human body. During this process, leathers are subjected to various types of
mechanical stresses, which are indispensable for the garment appearance [6]. In garment
manufacturing, a two dimensional structure is converted into a three dimensional structure. During
the process of sewing, the needle is subjected to repeated tensile stresses, heat, bending, pressure and
wearing. These stresses repeatedly act on the thread as a result of which leather is subjected to
various types of mechanical stresses which are low stress in nature [7].
The term sewability can be defined as the ability and the ease with which the 2-D fabric
components can be qualitatively and quantitatively be seamed together to 3-D garment [8]. Better
sewability means greater ease of formation of shell structures and styles with the absence of fabric
distortion and seam damage. The appearance and durability of seams form an important component
of the quality of the finished product [9]. Damage of the structure of the fabric occurs when the
fabric is penetrated by the needle. The needle can penetrate at any point in the fabric. The structure
of the fabric can be deformed beyond its elastic limit or can literally be destroyed [10].
The sewing needle penetration force which is one of the most significant technical parameter
in the sewing process is the quantitative measure of the damage that appears in a garment as the
result of the sewing process [11]. A high penetration force means a high resistance of the fabric and
thus a high risk of damage [12]. The sewing needle penetration force is affected by various factors
such as type and amount of layers of the sewing material, needle size, shape of needle point, stitch
speed of the sewing machine, and treatment of the sewing material, among others [13]. The fabric
should withstand the needle penetration without any damage to the fabric [10].
Although many sewability studies have been carried out on textile fabrics, there is not much
study related to sewability of garment leathers. It is accepted that leather as a material needs more
penetration force for the needle. However leather properties vary in a very wide range depending on
the animal type it is obtained from and the process type and chemicals used in the manufacturing.
The present work aims determination of the sewability properties of garment leathers tanned with
various tanning materials which are chromium, vegetable and chromium-vegetable combination.
Sewability of these garment leathers were compared with each other in terms of the average needle
penetration force (gf) and the sewability value (%). A good seam is a measure of quality in leather
garments. The results of this study will give data to be considered in sewing to obtain better seams
for manufacturing of high quality leather garment products.
2. MATERIAL AND METHOD
2.1 Material
In this research 3 chromium, 3 vegetable and 3 chromium-vegetable combination tanned
garment leathers (English origin sheep skins) obtained from a garment leather manufacturing factory
were used. The samples were analyzed by using L&M Sewability Tester as three parallels vertically
and horizontally.
ANNALS OF THE UNIVERSITY OF ORADEA
FASCICLE OF TEXTILES, LEATHERWORK
199
2.2. Method
Sampling of leathers were done according to TS EN ISO 2418. The tests were carried out at
the same conditions according to TS EN ISO 2419. The thicknesses of test samples were measured
according to TS 4117 EN ISO 2589. Apparent density of leathers was calculated according to TS
4121 EN ISO 2420 [14-17].
Fig.1: L&M Sewability Tester
The sewability properties of the leathers were determined by using L&M Sewability Tester
(Fig. 1). It enables consecutive readings of force for penetration of the fabric by a selected needle to
be measured on a small sample of fabric at a rate of 100 penetrations/min [18]. This device measures
the penetration force exerted by a sewing needle on the fabric. A strip of fabric passes through a
zone in which a sewing needle operates. A nominal value (threshold) of penetration force is
determined based on the fabric mass per unit area according to the fabric type, and then the number
of times this value is exceeded is recorded. Fabric sewability corresponds to the number of points
that exceed the threshold previously set, related to the over-all tested points and expressed as a
percentage. The sewing operation will be more difficult as the sewability parameter increases [19].
In this study the device setting was maintained constant for all the tests; the total count per
leather was 100; the force range chosen was 500gf, and the threshold value for sewability
determination was 150gf. The number of high recordings which exceed the threshold value, which is
called the “sewability value”, was also recorded.
3. RESULTS AND DISCUSSION
The weight and thickness properties of garment leathers tanned with chromium, vegetable
and chromium-vegetable combination were determined and are given in Table 1. Vegetable tanned
leathers are known to give denser and thicker leathers; contrary chromium tanned leathers are
famous with their light, soft and thinner character. Apparent density of chromium tanned leathers
and vegetable tanned leathers vary between (0,680 - 1,000 g/cm3) and (0,780 - 1,150 g/cm3)
respectively [20]. When the apparent density figures in Table 1 are considered, they are in
accordance with the reference limits. Although thickness of leathers are adjusted by mechanical
operations to give a uniform distribution across the whole area; vegetable tanned leathers were found
thicker than chromium-vegetable combination tanned leathers and chromium-vegetable combination
tanned leathers were found thicker than chromium leathers.
Table 1: The properties of garment leathers.
Leather type
Weight (g/m2)
Thickness (mm)
Apparent density (g/cm3)
Chromium
290,62
0,52
0,71
Chromium-Vegetable combination
363,96
0,59
0,79
Vegetable
420,95
0,61
0,87
ANNALS OF THE UNIVERSITY OF ORADEA
FASCICLE OF TEXTILES, LEATHERWORK
200
Fig. 2: Average Needle Penetration Force of Different Tanned Leathers.
As it can be seen from Fig. 2, the values of needle penetration force were varied between
111 gf and 284 gf.
Vegetable tanned leathers had higher needle penetration force and sewability values than
chromium tanned leathers. However semi-vegetable leathers had the highest needle penetration force
and sewability values in both directions. These findings could be related to physical properties of the
used leathers. Ork et al. (2014) also found that semi-vegetable tanned leathers came into prominence
with their high strength and low extension set properties which are important for garment leathers.
When physical test results of leathers tanned with different tanning types were statistically
evaluated, it was concluded that tanning type has important effect on the physical properties of
leathers even from the same origin. Physical properties of the leathers were varied due to the tanning
material used in their production [1].
Fig. 3: Sewability values of Different Tanned Leathers
When sewability values ranged between 0 and 10%, the fabric sewability was considered
good; between 10 and 20% sewability was considered to be only fair even though no great
difficulties arose during sewing [21].
As it can be seen in Fig. 3, sewability values of chromium tanned leathers were found 13.4%
horizontal and 14.2% vertical which could be accepted a fair value close to good. However
vegetable tanned leathers and chromium-vegetable combination tanned leathers had sewability
values of 38.2% horizontal, 49.2% vertical and 98% horizontal, 98.5% vertical respectively. So the
sewabilities of these samples are considered poor. This means that an extra attention is required to
obtain seam quality in production of garment leathers tanned with vegetable or vegetable-chromium
combination tannage.
ANNALS OF THE UNIVERSITY OF ORADEA
FASCICLE OF TEXTILES, LEATHERWORK
201
Ork et al. (2014) found stitch tear values of chromium, vegetable and chromium-vegetable
tanned leathers as 334 N/cm, 518 N/cm and 786 N/cm respectively [1]. Although stitch tear
resistance test is a static test which is done in tensile testing equipment and sewability test is a
dynamic test done with L&M sewability tester, there seems a consistent relation between the results
as seen Fig. 4.
Fig. 4: Average Needle Penetration, Stitch Tear Resistance and Sewability values of Leathers
5. CONCLUSIONS
In the last decades there is a demand on natural products in leather industry as in many
industries. Vegetable tannins which are known to give heavy, strong and durable leathers are now
being used in the production of soft, light and elegant garment leathers either alone or in
combination with mineral tanning materials. Undoubted, tanning materials have a significant effect
on the material properties of leathers produced. In this study, sewability of garment leathers tanned
with chromium, vegetable and vegetable-chromium combination tanning agents has been
determined and the following conclusions have been found:
Chromium leathers were found having the lightest weight, the thinnest and the less apparent
density followed by chromium-vegetable combination and vegetable tanned leathers.
Vegetable tanned leathers had come closer to the characteristics of chromium tanned
leathers; however there are still some differences in properties.
Average Needle Penetration Force was found lowest for chromium tanned leathers, followed
by vegetable and chromium-vegetable tanned leathers in order. That means chromium
tanned leathers can be sewn with a less needle force, and more needle force is required for
vegetable and chromium-vegetable tanned leathers.
Chromium tanned leathers had sewability values of 13.4% horizontal and 14.2% vertical
which are considered good to fair. Vegetable tanned leathers and chromium-vegetable
tanned leathers had sewability values of 38.2% horizontal, 49.2% vertical and 98%
horizontal, 98.5% vertical respectively which are considered poor.
When the results of dynamic sewability test are compared with static stitch tear test, the
relation among the data was found consistent, even the tests have totally different principles.
Leather is a luxury product due to limited supply, high cost of material and labor. This
luxury product should maintain all the quality and environmental requirements. Besides; garment
design and manufacturing quality have also big importance. The design should meet the fashion,
comfort, aesthetic expectations of the consumer. Leather garments contain many joining and
ornament seams due to small patterns related to animal size. These seams should be proper to meet
the quality aspects. The results conclude that, there is a big difference in material properties when
the tanning technology and material is changed which also affects the sewing properties.
ANNALS OF THE UNIVERSITY OF ORADEA
FASCICLE OF TEXTILES, LEATHERWORK
202
REFERENCES
[1] N., Ork, H., Ozgunay, M. M., Mutlu and Z., Ondogan, "Comparative Determination of
Physical and Fastness Properties of Garment Leathers Tanned with Various Tanning Materials for
Leather Skirt Production", Tekstil ve Konfeksiyon, vol. 24, pp. 414-418. 2014.
[2] Covington A., 1997, Modern tanning chemistry, Chemical Society Reviews, pp. 111-126
[3] Fathima, N. N., Saravanabhavan, S., Rao, J. R. et al., "An eco-benign tanning system
using Al, tannic acid and Silica combination". J. Amer. Leather Chem. Ass., vol. 99, 73.1, 2004.
[4] Jones C., "The manufacture of vegetable tanned light leathers Part 1", World Leather,
pp. 80-83, 2000.
[5] Urbanija, V. and Gersak, J., "Impact of The Mechanical Properties Of Nappa Clothing
Leather On The Characteristics of Its Use", Journal of The Society of Leather Technologists and
Chemists, vol. 88, pp. 181-190, 2004.
[6] K. Phebe, P. Thanikaivelan, K. Krishnaraj and B. Chandrasekaran, "Factors Influencing
the Seam Efficiency of Goat Nappa Leathers", JALCA, vol. 107, pp. x-y, 2012.
[7] K. Phebe, B. Chandrasekaran and M. Asit Baran, "Sewability of sheep nappa garment
leather," RJTA, vol. 18, pp. 49-55, 2014.
[8] E, Z, Yildiz, O, Pamuk, Z, Ondogan, "A Study About The Effects of Interlinings to
Sewability Properties of The Woven Fabrics", Tekstil ve Konfeksiyon, vol. 21, 1, pp. 87-90, 2011
[9] K. Phebe, P. Thanikaivelan, K. Krishnaraj and B. Chandrasekaran, "Influence of
mechanical properties of sheep nappa leathers on seam efficiency", Journal- Society of Leather
Technologists and Chemists vol. 95(1), pp. 16-22, 2011.
[10] K. Phebe, B. Chandrasekaran, "Performance of Needles on Sewability of Garment
Leathers", Revista de Pielarie Incaltaminte, vol.11, 2011.
[11]F. Fathy Saied and Z.M. Abdel-Megeid, "The relation between fabric construction,
treatments and sewability," Journal of American Science, vol. 7, pp. 272-280, 2011.
[12] A. Gurarda and B. Meric, "The effects of elastane yarn type and fabric density on
sewing needle penetration forces and seam damage of pet/elastane woven fabrics," Fibres &
Textiles in Eastern Europe, vol. 15, pp. 73-76, 2007.
[13] D. Ujević, D. Rogale, M. Kartal and B. Šajatović, “Impact of sewing needle and thread
on the technological process of sewing knitwear,” Fibres & Textiles in Eastern Europe, vol. 16, pp.
85-89, 2008.
[14] TSE, TS EN ISO 2418 Leather - Sampling location.
[15] TSE, TS EN ISO 2419 Leather - Sample preparation and conditioning.
[16] TSE, TS 4117 EN ISO 2589 Leather - Determination of thickness.
[17] TSE, TS 4121 EN ISO 2420 Leather - Determination of apparent density.
[18] The L&M Sewability Tester Catalogue.
[19] A.M. Manich, J.P. Domingues, R.M. Sauri and A. Barella, "Relationships between
Fabric Sewability and Structural, Physical, and FAST Properties of Woven Wool and Wool-blend
Fabrics", Journal of the Textile Institute, vol. 89, part 1, no. 3, pp.579-589, 1998.
[20] H. Herfeld, Bibliothek des Leders, Band 10 Reutlingen, 1982.
[21] A. Gurarda, B. Meric, "Sewing needle penetration forces and elastane fiber damage
during the sewing of cotton/elastane woven fabrics", Textile Research Journal, vol.75, pp.628-633,
2005.
... There are different properties that garment leather should have, such as lightweight, fastness (to rub, light, wash, etc.), durability, drapability, etc. [5]. On the other hand, the drape is the most significant garment feature, since it contributes to wear comfort [6]. ...
Article
Full-text available
Understanding the performance and behavior of garment leathers provides valuable inputs for the design and production of leather garments. The drape is one of the important properties associated with garment fitness quality and appeal. This study aims to show how the independent variables flexural rigidity and thickness affect the dependent variable drapability. Nowadays, studies on the drape of garment leathers are scarce. In this work, the drape coefficient (DC) was measured for sheep garment leather, which influences the garment drapability, such as flexural rigidity in the range of 9.2 to 22 and thickness in the range of 0.64 to 0.96. The average DC was calculated in the range of 47.35 to 69.9% for the selected sheep leathers from four samples. The drapability of the garment leather was determined using the DC. Flexural rigidity and thickness have been shown to have a considerable influence on the DC, while they do bear a significant relationship to the DC. The results of this study can be used as an elementary tool for leather selection of appropriate materials for garments.
Article
Full-text available
Interlining is a layer of knitted, woven or non-woven fabric placed between the garment fabrics and facing to reinforce, to give form and to prevent stretching. They are usually used for collars, cuffs, waistbands, pocket flaps and plackets. In this study, the woven fabrics and the woven interlinings that are usually used for shirts manufacturing were examined. 4 woven interlinings and 3 woven fabrics, that have same constructions but different weights were determined. The aim of this paper is to research sewability properties of different woven fabrics fused with different woven interlinings by using the L&M Sewability Tester. The findings were associated with the penetration force, fabric unit weight and fabric thickness. It was found that when the weight and thickness level of fabrics increase, the resistance to sewability increases, too.
Article
Full-text available
This paper presents the effects of elastane yarn type and fabric density on the seam performance of PET/elastane woven fabrics. In this study, 12 different weft stretched fabrics were woven with 2 different weft yarns, 2 different weave types and 3 different weft densities. The weft and warp yarns of the weft stretched fabrics were polyester- elastane covered yarn and polyester yarn, respectively. Air-covered and twisted elastane weft yarns were used at twill and plain fabrics. Needle penetration forces were determined on an L&M Sewability tester for seam performance. Besides this, "needle damage index" was calculated for seam damage. The values of the needle penetration forces were between 64 cN and 370 cN and the needle damage index values were between 18% and 73%. Elastane yarn type and fabric density had significant effects on the needle penetration force. Photographs were taken with an optical microscope to show the seam damage during sewing.
Article
Full-text available
One of the best ways to combat chrome pollution is to avoid chromium itself in tanning. With this view, a chrome-free combination tanning system has been established using aluminium, tannic acid, a precursor to vegetable tannins and silica. Since tannic acid has low molecular weight compared to vegetable tannins, it can be successfully used to make a variety of leathers and the problems associated with vegetable tannins like hard biodegradability of tannins, fullness and darkness of leathers can be avoided. The presence of aluminium not only improves the hydrothermal stability of leather but also gives a pleasant pastel color to the leather due to the formation of aluminium-tannic acid complex, which produces colour in the matrix thus leading to the concept of natural dyeing. The fastness properties of the color obtained have been studied and have been found to be significantly good. The presence of silica in the combination system gives rise to softness and fluffiness. The amount of tannic acid, aluminium sulfate and sodium metasilicate has been chosen as 10, 5, and 5% (on pelt weight), respectively. In order to avoid pollution due to pickling operation, pickle-less tanning has been carried out. Both upper and garment leathers have been made and the characteristics of the same have been studied. The shrinkage temperature of the leathers obtained from this combination tanning system is about 95°C. The physical strength characteristics and the organoleptic properties of the leathers obtained are on par with or better than the conventional chrome tanned leathers. The effluent arising from this tanning system has been analyzed for its environmental impact. The exhaustion of aluminium is about 98%. Also, there is significant reduction in the COD and TDS. Thus, an eco-benign chrome-free combination tanning system has been established.
Article
Full-text available
In the present study, physical and fastness properties of the leathers, which are obtained from two different tanneries, similarly processed in each tannery however, differentiated from each other by tanning with chromium, vegetable and chromium-vegetable combinations and planned to be used in skirt manufacture were determined with various quality control and analysis methods and evaluated by considering their field of use. Additionally it was statistically investigated whether there is a significant difference between the physical characteristics of leather depending on the type of tanning material used. Consequently, it was deduced that the type of tanning material used in leather production has statistically significant effect on the physical characteristics of the leathers which are produced from the same origin.
Article
Full-text available
This paper presents an experimental study of the effects of elastane draw ratio, pre-setting temperature and finishing process on the penetration forces of a sewing needle and damage to the elastane fibre during the sewing of cotton/elastane woven fabrics. Seam strength and seam opening strength of the fabrics were also determined for assessment of seam performance. In this study three fabric types with three different elastane weft yarn draw ratios were taken as samples for the experiments. As the first step a pre-setting process was applied to all three types of fabric at two different temperatures and at the finishing process half of the samples were treated with silicone and the other half were washed only. In total, 12 samples having different specifications were obtained. For these fabrics, nylon/elastane air-covered yarn was used as the weft yarn and cotton yarn as the warp yarn. Seam strength, seam opening strength, needle penetration forces and “needle damage index” were determined for these fabric samples. The needle penetration forces were between 100 and 140 cN and the “needle damage index” values were between 20 and 42%. Photographs were taken with an optical microscope and a scanning electron microscope to show the elastane fiber damage during the sewing.
Article
Quality is an important aspect of the apparel manufacturing process. Although the basic quality of apparels mainly depends on the fabric properties, the type of thread used and selection of seams play an important role in determining the final quality of the apparel. Seam strength testing is basically an examination of the amount of pressure required to tear the seam of a garment. It is an essential parameter that determines the performance of a garment. For the perfect fit and look of a garment, seam strength has to be proper. It is therefore worthwhile to select the correct sewing thread size for good seam quality. The present work reports on an experimental investigation about the effect of different threads on the characteristics of leather. The other parameters, which are investigated, include seam strength, puckering and slippage.
Article
Leather, when used as the primary component of clothing, requires specific care in design linked to the specific traits of individual hide types and their mechanical properties. This study attempts, with reference to the specific properties of leather, to explore the impact of nappa leather clothings' mechanical properties on the characteristics of its use. This research work deals with a mechanical properties analysis of sheep- and pigskin nappa leather clothing. Particular emphasis is placed on handle, the tensile, elastic and shear properties, as well as bending characteristics and design abilities and/or drape of the leather. Special emphasis is placed on the comparative analysis of pig- and sheepskin nappa leather clothing. The survey involved 31 skins of various nappa clothing sheepskin designed for outer garments which were divided into three groups by weight and by mass and four groups of nappa clothing pigskin. Three of the groups of nappa pigskin differed in the method of finishing, whereas the fourth group included washable nappa pigskin. All of the groups of nappa leather clothing analysed were tested for their interrelationships on the important parameters of mechanical properties typical of an individual hide group. In parallel with analysis of the mechanical properties of the nappa leather used, the effects of mass and bending rigidity on the nappa leathers' drape were also explored. "Mass" here is used in the sense of mass/unit area and is expressed in gm-2. Based on an analysis of the results obtained for individual parameters of the nappa pigskin's mechanical properties, it was established that there is no substantial deviation in the properties concerned from the values for nappa sheepskin.
Article
The present study provides scientific knowledge related to the strength and other performance factors of the types of needle points. The combination of material, needle point and thread is what produces a good seam. Garment leathers (goat leathers) were subjected to strength tests using Universal testing machine. Results obtained clearly indicate that diameter, size of needles and type of needle points play crucial role in the strength of leathers subjected to stitching.
Article
The selection of sewing needles, the fineness of sewing thread, relative air humidity, as well as the thickness and density of knitted fabric play a significant role in the technological process of sewing. Damage to knitted fabric loops during sewing are closely connected with sewing needle penetration force and dynamic tension values of the sewing thread. In this research an instrument for measuring the sewing needle penetration force and dynamic sewing thread tension force was designed.
Article
The range of chemistries used for tanning leather is reviewed; traditional methods of tanning are explained and the newer processes are described. The areas of tanning include: vegetable tanning with plant polyphenols, mineral tanning with metal salts, in particular chromium(III), oil and aldehyde tannages, synthetic tanning agents and organic tannages based on natural polyphenols or synthetic organic oligomers. The fundamental nature of the tanning reaction and the origin of hydrothermal stability are discussed.