Types Of Leather Research Articles

The Use of Natural Scientific Methods in the Study of Leather Items from Archaeological Excavations

This article outlines the results of analyses of footwear and other late medieval and recent leather items. Orthopedic diagnostics are used to assess an early 18th-century woman’s shoe from the historic center of Kaluga. The insole, made of tightly fitted cords, suggests that the shoe had a corrective function. Infrared spectroscopy and liquid chromatography were used to analyze the leather of which the quiver found during the excavations in Moscow was made, and to evaluate the technique whereby its surface was processed. Natural scientific methods were used to study the various types of leather and threads, and to reconstruct the decorative techniques. Leather footwear from the medieval town of Galich, near Kostroma, is compared to that from other Central Russian towns, revealing local variations in footwear and the distribution areas of its types. It is concluded that natural scientific methods are helpful in the study of such finds.

Investigation of Flame Retardant Effects of Resins on the Flammability of Leather

Natural leather products, which are by-products of the meat industry, are used because of their high air vapor permeability and elegant appearance compared to synthetic leather. The production of flame retardant leather is important for some leather types such as motorcyclist jackets, flight or automotive upholstery leathers, military boots. It is frequently mentioned in the literature that resinous chemicals create flame retardant effects in textile materials due to their nitrogen content. Urea, melamine and dicyandiamide resins are always used in the traditional retanning process of cattle leathers. It has been investigated which of these resins has the highest flame retardant effect on the leather. In the study, 2%, 3% and 4% ratios were studied for these three resins; flame resistance of the leathers were investigated by LOI and TGA analysis. The study also examined the chemical effects of resins on the leather surface with FTIR and SEM analyses.

Leather used in Furniture Upholstery

Nowadays, there is a lot of leather material in the international market with different specifications and qualities. Since the furniture production, especially for the upholstered sofa, chairs, and similar products, are assembled and connected with a combination of glue and connectors, we need a specific selection for each product. Types of leather and their qualities are varied as well as the price. To assure the quality of the product we need to define many factors affecting the durability of the leather build in the furniture. Testing the planned leather is always recommended.

Application of a Medical Diode Laser (810 nm) for Disinfecting Small Microbiologically Contaminated Spots on Degraded Collagenous Materials for Improved Biosafety in Objects of Exceptional Historical Value From the Auschwitz-Birkenau State Museum and Protection of Human Health.

The research aim was to optimize the operating parameters of a diode laser irradiation for the effective disinfection of degraded collagenous materials. Historical leather shoes stored at the Auschwitz-Birkenau State Museum in Oświęcim (Poland) were the main study objects. Surfaces of contaminated small spots occurring on the degraded materials were sampled with moistened swabs and microbiologically examined using the molecular techniques MALDI-TOF MS, 16S rRNA, and NGS sequencing. The surfaces were colonized by bacteria with 106 CFU/100 cm2 and 104 CFU/100 cm2 by fungi, on average. Microorganisms of the genera Bacillus and Penicillium were predominant. The effectiveness of the laser treatment was assessed for the new and degraded collagenous materials against isolated environmental strains using four variants of exposure time and number of repetitions. 0.3 W/CW 2 × 2 min variant was the most effective and also did not noticeably change the color of the treated samples. The variant caused a reduction in the numbers of microorganisms by 96–100%. After 1 month, four types of leather were subjected to comprehensive physico-chemical analyses. SEM and FTIR techniques confirmed that laser irradiation in the selected optimal variant did not affect the surface morphology and collagen structure, while XPS technique enabled detection of subtle changes in non-historical protective coatings on the surfaces of tested degraded historical materials.

Mechanical properties and preferences of natural and artificial leathers, and their classification with a focus on leather for bags

In this study, the mechanical properties and preferences of natural and artificial leathers were analyzed. The leathers were classified based on mechanical properties affecting their preferences. The mechanical properties of the leathers were measured via the KES-FB system, and an expert survey was conducted to evaluate leather preference. Leathers possess different mechanical properties depending on the manufacturing process and structural characteristics. Furthermore, differences were observed in the mechanical properties of natural and artificial leather. The mechanical properties of the leathers were related to the preferences for hand and bags. Accordingly, the leather was classified into three clusters. The leathers that were preferred for hand were not preferred for bags, and those preferred for bags were not preferred for hand. Therefore, different development strategies are needed, depending on the type of leather. Natural leather for bags should be light and have good compression elasticity along with its existing mechanical properties, whereas artificial leather should be light and have improved tensile resilience.

Leather Thermal and Environmental Parameters in Fire Conditions

The thermal decomposition of leather-product combustion produces some inflammable and harmful compounds after tanning, fat liquoring, dyeing, and finishing processes. These organic compounds are ignited and release a lot of toxic gases and smoke in fire conditions, polluting the atmosphere air. On this account, it is very important to know leather safety performance for fire prevention. The flammability and thermal stability of types of leather at thermal expositions stimulating fire conditions were analyzed. Five types of leather were used in experimental testing, four of animal origin and an artificial one. Results showed that, in the analyzed heat exposure, the highest average heat-release rate (174 kW/m2) and smoke generation, and the lowest temperature of the beginning of thermal decomposition, were recorded for the artificial leather. Leather flammability essentially depends on the type of applied energy stimulus, as well as hide composition and origin. A possible cause for differences in the obtained results of the leather analyses is the percentage of certain leather components and their chemical composition.

Problems with perfect-looking two-needle decorative seams in the manufacture of leather car seat covers

This study objectively evaluates the uneven appearance of the two-needle decorative seams of leather seat covers. The investigation is based on both measurement of the stitch slant angle by image analysis and measurement of the penetration force influenced by different cutting points of the needles. To record the unevenness the new parameter, the difference of the stitch slant between the right- and left-hand sides of the seam was evaluated. Further, the interrelation ship among penetration force differences of the stitch slant and type of needle point was searched for to meet the requirements of car producers for a perfect appearance of decorative seams. The degree of uneven seam was measured within subjective visual evaluation, too. Four natural and two artificial leathers were tested. A combination of two threads and four needle points was applied to the tested leathers. It was confirmed that the uneven appearance was influenced by the type of leather, the point of the sewing needle and by the sewing thread. The selection of the needle point influenced the size of the force required for penetrating the leather. It was determined only in half of the cases that the smaller the force of penetration, the more even the appearance of the decorative seam. In most cases, using the cutting point LR, the left seam looked less slanted than the right one. Conversely, when using the cutting point for straight stitch appearance, that is, DH, the left stitch looked straighter than the right one. The causal link between the new parameter Δβ and the suitability of the applied needles and threads for leather materials was found.

The Utilization of Chitosan as Natural Antibacterial for Vegetable Tanned Leather

Leathers, which are made from natural fibers, can serve as media for microorganisms to grow. The currently used antimicrobial agents or biocides in the leather industry are harmful to human health and the environment. Therefore, the use of antimicrobial agents should be restricted. This study aims at developing eco-friendly biocides that could substitute for toxic chemicals as it will be tested on vegetable-tanned leather. Due to their large surface area and ability to retain moisture, the vegetable tanned leather has a higher possibility of biodeterioration than other types of leathers tanned by mineral tanning agents. In this work, the natural biopolymer of chitosan was chosen for its ability to inhibit the bacterial growth. The results showed that chitosan coating by impregnation method in drum using chitosan/leather ratio of 1% in formic acid for 2 hours is successfully achieved the bacterial growth inhibition.

Effect of punching on physical and mechanical properties of leathers: Focus on car seat covers

As a lot of time is spent in the car, the comfort of not only the car seat but also the car seat cover itself has become of increasing importance. With increasing use of ventilated seats, the control of the physical and mechanical properties of leather in response to punching has become of prime importance in the design of car seats. This study evaluated the changes in the physical and mechanical properties of leather due to punching and proposes optimum punching intervals for car seats. Sixteen types of leather, punched at three spatial intervals (2, 3, and 5 mm), were evaluated in terms of their apparent density, softness, coefficient of friction, warm-cool feeling, and mechanical properties. Leather punching affected its physical and mechanical properties. However, there were differences in punching intervals that significantly affected each property, including the mechanical properties. Depending on the performance required when developing a product, a suitable punching interval must be selected. Therefore, punching at 5 mm intervals is preferred for obtaining physical and mechanical properties similar to those of untreated leathers, and punching at 3 mm intervals is recommended for achieving more softness. On the contrary, punching at 2 mm intervals increases air permeability but decreases dimensional stability.

DEVELOPMENT OF COMMERCIAL FLAME RETARDANT IN UPHOLSTERY LEATHERS BY BORON DERIVATIVES

The production of flame retardant leather is significant for some leather types as aircraft and automotive upholstery leathers, and protective leathers as for motorcyclist jackets. For this reason, in this research it was aimed to modify effect of commercial flame retardant (CFR) on upholstery leathers treated with borax, boric acid and zinc borate. Control (group 1), 200 g/L CFR (group 2), 10 g/L borax + 60 g/L boric acid + 200 g/L CFR (group 3) and 10g/L zinc borate + 60 g/L boric acid + 200 g/L CFR (group 4) chemical solutions were applied to the leathers by padding finishing technique, and after the flame retardant application the leathers were finished with traditional finishing recipe. Flame retardant property of leathers was determined by vertical flammability (ISO 6941:2007) and limit oxygen index (LOI) (ASTM D 2863-77) fire resistance tests. In addition, the treated leathers were characterized by ATR-FTIR and SEM devices. According to LOI results, CFR CFR+borax+boric acid and CFR+zinc borate+boric acid treated groups of leather had 28.5%, 29.2% and 29.9% oxygen concentration respectively, while control sample had 27.0%. Flame retardant property of leathers was significantly enhanced by the effect of boron derivatives.

Tearing behaviour of two types of leather: A comparative study carried out at the local scale using the full kinematic and thermal field measurement techniques

AbstractLeather materials undergo various strain and stress states during their elaboration process and their application in numerous different functions. Among the key properties required for such materials, tearing resistance appears as one of the most important. In this paper, the tearing behaviour of two types of leather, a grain pigskin leather and a grain calf leather, was investigated at the local scale using the full‐field techniques. During the tests, thermal fields were measured at the surface of the two leathers by means of an infrared camera. Measurements of the displacement and deformation fields were also performed at the surface of the pigskin sample using the digital image correlation technique, which was not possible for the calf sample due to surface wrinkling. The results obtained enable us to discuss and compare the tearing resistance of both leathers in terms of the thermal activity in the zone of influence of the crack. The best tearing resistance was obtained for the grain calf leather that has undergone a retanning operation and whose matrix contained a plasticiser.

Pre-Trained Convolutional Neural Network for Classification of Tanning Leather Image

Leather craft products, such as belt, gloves, shoes, bag, and wallet are mainly originated from cow, crocodile, lizard, goat, sheep, buffalo, and stingray skin. Before the skins are used as leather craft materials, they go through a tanning process. With the rapid development of leather craft industry, an automation system for leather tanning factories is important to achieve large scale production in order to meet the demand of leather craft materials. The challenges in automatic leather grading system based on type and quality of leather are the skin color and texture after tanning process will have a large variety within the same skin category and have high similarity with the other skin categories. Furthermore, skin from different part of animal body may have different color and texture. Therefore, a leather classification method on tanning leather image is proposed. The method uses pre-trained deep convolution neural network (CNN) to extract rich features from tanning leather image and Support Vector Machine (SVM) to classify the features into several types of leather. Performance evaluation shows that the proposed method can classify various types of leather with good accuracy and superior to other state-of-the-art leather classification method in terms of accuracy and computational time.

Influence of some mechanical finishing processes on manufactured leather properties

The objective of this study is to investigate the influence of using some mechanical finishing processes on final properties of produced leather types. Nappa, nubuck, pigmented and corrected grain leather types were produced by applying some of the following operations: hang drying, vacuum drying, molissa staking, drum milling, buffing, spraying and/or embossing surface with extreme pressure. Hydrophobic-hydrophilic status, scanning electron micrographs, organoleptic and mechanical properties were determined on all finished leather types. Results showed that water behavior was hydrophobic for nappa leathers, while it was hydrophilic with the rest of produced leather types. Buffing surface in nubuck leather increases the water absorption and water vapor permeability, while the opposite was found when applying external coat layer in pigmented and corrected grain leathers. Applying vacuum drying in nappa leathers increases surface smoothness and surface water contact angle while decreases tensile and tearing strengths. These results elucidate that all studied leather types are suitable for manufacturing purposes except nubuck leather which is not recommended for footwear uppers manufacturing due to its high water absorption. The present study emphasized that while mechanical finishing processes could have profound effects on leathers surface behavior, they must be adequate to the requirements and properties of the end products.

The Subjective Hand and Preferences Evaluation of Artificial Leather by Use

Sensory attributes and preferences that contribute to consumer satisfaction with artificial leather were measured by subjective evaluation, and subjective hand and preferences were analyzed in relation to its use. Using tactile and visual senses, 50 experts in fashion and textile industry evaluated leathers classified into two categories, suede and polyurethane coated, according to different manufacturing methods. They answered questions on subjective hand and preferences of different artificial leathers of various fashion items (jackets, purses, bags, shoes, boots, furniture, etc.), using specific adjectives to describe the hand properties. As a result, it was found that the subjective hand properties of artificial leathers were related to 'Thickness', 'Fullness/softness', 'Surface contour', 'Stickiness', and 'Elasticity'. The leather type from different manufacturing methods influenced their perceived hand and preferences relating to use. By use, different hands were preferred. The preferences for jackets and furniture of suede type leathers were related to their surface properties, whereas the preferences for items of the other type of leathers were associated with their resilience. On the other hand, in the case of polyurethane coated leathers, the preferences for jackets were significantly affected by their thickness, while those for the other items were influenced by their resilience and surface properties.

Dehydrated apple matrix supplemented with agave fructans, inulin, and oligofructose

The objective of this study was to determine the effect of supplemented prebiotics: inulin (I), oligofructose (O), agave fructans (A) and their mixtures in three levels, 20, 40 and 60 g prebiotics/kg puree on the physicochemical and sensorial properties of a dehydrated apple matrix (DAM), fruit leather type. A simplex-centroid design was used to formulate the different mixtures. After that, fructans were identified in the matrices using thin-layer chromatography and high-performance anion-exchange chromatography with pulsed amperometric detection and enzymatic kits. A descriptive quantitative method was used to determine sensory profile of the matrices. The sensory acceptability was measured by a 7-point hedonic scale. Matrices supplemented with solely A and O, were significantly smoother and more qualified in acceptability compared to the control. The behavior of DAM with inulin was different; it increased hardness and decreased acceptability. In general, mixtures of prebiotics had a synergistic effect on matrices hardness. The optimum formulation corresponded to the DAM supplemented with agave fructans, indicating that it is possible to obtain a fruit leather type product with prebiotic potential.

Pilot-Scale Study on Masking Agents for Titanium Tanning

The many advantages offered by chrome tanning justify its widespread use for production of almost all types of leather. However, the traditional chromium (III) tanning process is constantly under threat from the pressure of legislation, and ever-tightening restrictions require to minimize chromium-containing effluents discharge and chromium-containing wastes production. Recently, the manufacture and use of chromium (III) free tanning agents compounds have been studied intensively. Among these, Titanium (IV)-based salts is one of the most promising substitutes.In this study, the use of titanyl sulfate as tanning agent for the production of high-quality bovine upper leather was investigated. In order to optimize the titanium tanning performances, a comparative evaluation, on pilot-scale, of citrate and lactate ions as masking agents was performed.The developed process has been validated through various analyses of the obtained crust leathers such as shrinkage temperature, scanning electron microscopy, and physical testing. The final leather obtained with the innovative method shows similar properties to those of the conventional tanned leather in terms of technical and mechanical properties.

Effect of sewing machine and thread type on the quality of leather garments

Sewing Machine is one of the most important factors affecting the quality of the clothing industry. Also, leather garments require special care during sewn. The purpose of this paper is to study sewing leather fabrics Techniques to reach the highest degree of quality and efficiency of sewingleather and the efficiency of functional and aesthetic appearance of clothing and age consumer. And by identifying some of the research variables, there was two leather type (sheep natural leather – Pu artificial leather), the skin of sheep is the most commonly used types of leather in the field of leather garments.There was a comparison between two types of sewing machines (Ordinary sewing machine – leather sewing machine) and using two types of thread (polyester – nylon). Then we examined leather using a number of test methods like thickness, tensile strength, abrasion and seam pucker according to standards. . Tests took place into conditioned atmosphere of 21ºC and 65% RH. Comparisons have been made between the two different types of sewing machines and also between the two different thread types this was done with reference to seamed lines’ durability, efficiency and appearance. In conclusion we was able to determine the best quality to sew leather garments in terms of identifying the type of sewing machine-the type of sewing thread To suit every type of leatherin this test.

Susceptibility of Indian Leather for Fungal Attack

Fungi play an important role in the degradation of leather and service leather goods. In the present study 20 types of Indian tanned leathers have been tested for their resistance/susceptibility against mycobial attack. 9 common species i.e. Aspergillus niger, A. flavus, A. fumiqatus, A. nidulans, A. terreus, A. sulphureus, Penicillium cyaneum, Paecilomyces varioti and Mucor sp. were isolated from various types of leather samples. E. I. tanned (goats & cows) and pure vegetable upper leathers were found highly susceptible and supported very good fungal growth. Vegetable chrome, full chrome B, and blue chrome tanned (buffalo) were relatively resistant and chrome tanned split (cows) leather was found most resistant.

Eco-Leather: Properties of Chromium-Free Leathers Produced with Titanium Tanning Materials Obtained from the Wastes of the Metal Industry

In this research, a new titanium tanning agent (TMW/2) obtained from the wastes of the metal industry was investigated in the production of chromium free eco-leather, by experimenting with various amounts of tanning agent and comparing the physical and chemical properties of the tanned leathers. The tanning process was performed with different concentrations of active titanium tanning material such as 1%, 2.5%, 5%, 7.5%, and 10%. The titanium content, chromium oxide content, formaldehyde content, shrinkage temperature, pH value, ash content, and fat content of the tanned leathers were investigated for the determination of chemical characterization. The tensile strength, elongation at break, tear strength, and colour measurement tests were also carried out for investigating the physical properties. The titanium tanned leathers had a mean shrinkage temperature of 79.5oC and more yellowish colour than the chromium tanned leathers. Their tensile strength properties were found similar with chromium leathers, while the elongation at break was found to be lower and tearing resistance was higher. The usage amount of 2.5% could be perfectly advised for the tanning process based on the titanium tanning material for achieving optimal properties required from different leather types such as upholstery, automotive and shoe upper leathers. Consequently, our results showed that this new titanium tanning agent could be used as an alternative tanning material in the production of chromium free eco-leathers considering the visual, physical, and chemical properties of resultant leathers.

Diagnostic Analyses for the Study of Materials, Technique and State of Preservation of a Gilt and Painted Leather of the XVIII Century

In this study we report on the restoration work for the gilded and painted leather from the Sanctuary of the Santissimo Crocifisso di Papardura in Enna, Italy. The work started with a historical and stylistic examination of the artwork which dates back to 18th Century. The study of the leather and its decoration was deepened thanks to specific scientific analysis (such as XRF spectroscopy, Raman and SEM) in order to assure the integrity of the material during the restoration work. To this end, a diagnostic procedure was set up to provide a clear picture of constitutive materials (type of leather, silver leaf and pigments), technique, and state of preservation.