IOSR Journal of Environmental Science, Toxicology and Food Technology (IOSR-JESTFT) e-ISSN: 2319-2402,p- ISSN: 2319-2399.Volume 15, Issue 3 Ser. II (March 2021), PP 33-38 www.iosrjournals.org DOI: 10.9790/2402-1503023338 www.iosrjournals.org 33 | Page A Comparative Study on Physical Properties of Bag and Lining Leather from Two Different Origins Md. Farhad ALI 1 ,Mahbub KAMAL 2* 1,2 Institute of Leather Engineering and Technology, University of Dhaka, Dhaka-1209, Bangladesh Abstract In this study comparisons were done between the physical properties of bag and lining leathers from two different origins- cow and goat. Sample positioning, collection, preparation, conditioning and particular physical tests such as tensile strength, percentage of elongation at break, tearing strength, stitch tearing strength, water vapour permeability, grain crack load, scuff resistance, flexing endurance, bond strength between finish film and leather surface and colour rub fastness were done according to the standard ISO and SATRA methods. In some physical testssignificant differences were found between the bag and lining leathers.In case of bag leather the cow leather showed better results in the majority tests while the goat leather showed better results in grain crack load and flexing endurance tests only. Again, in case of lining leather, the cow leather showed better results in tensile strength, tearing strength, flexing endurance and bond strength tests while the goat leather showed better results in stitch tearing strength, water vapour permeability, elongation tests. In this case, cow and goat both types of leathers showed the same property in colour rub fastness test. Keywords: Leather, Bag, Lining, Physical properties. --------------------------------------------------------------------------------------------------------------------------------------- Date of Submission: 10-03-2021 Date of Acceptance: 25-03-2021 --------------------------------------------------------------------------------------------------------------------------------------- I. Introduction Leather consists of collagen protein based fibrillary network. In various organs of the body the appearance, length and thickness of these fiber bundles are dissimilar. So the properties of a leather depend on the position and direction over its area and it is not a uniform material from a structural perspective.Besides, it is a rawindustrial product with versatile applications in downstream sectors.Leather garments and products, footwear,furniture and many other items were made from leather. Leather products need various physical, chemical and fastness properties and specific performance characteristics depending on the field of use. The physical and chemical properties depend on the physical structure, chemical composition and mechanical operations during the leather manufacturing operation. Leathers are demanded to have sufficient strength and flexibility for the preparation of the final products [1].So, the physical properties of leather have a great significance and importance in the manufacturing of different types of leather product. The physical properties of leatherdepend on the animal individually and the type of animal. The purpose of this project work was to compare between the physical properties of the particular different types of leather. Stitch tearing strength, tearing strength, percentage of elongation at break, tensile strength,scuff resistance, grain crack load, bond strength between leather surface and finish film, water vapour permeability, flexing endurance and colour rub fastness etc properties of leathers were examined. Tensile strength and percentage elongation test is caused by a specified load and percentage elongation at break. A leather sample is elongated with certain speed until the force reaches a predetermined value or until the test piece breaks [2]. These two properties provide significant information about the quality of the leather texture [3].Tensile strength was determined by fibrous structures which constitute the collagen network structure and the modification of structure by tannins [4]. It is the ability of a material to withstand a longitudinal pulling force [5]. It is an important property as it relates to strength and performance of the material [6] The tensile strength increased with jaw speed, the rate of increase being least between 6 and 12 in./min. When the machine is operated by hand, the speed of the jaws may change from time to time [7]. Leather has very poor heat resistance. So, excess drying operation not only shrinks the leather but also makes the leather brittle and stiff as well as poor in tensile strength. Increase in drying time decreases the leather elongation at break [8].Elongation is the ability of a leather to extend when subjected to mechanical forces. It is an important consideration in the shape retention of apparels. Materials with low elongation tend to be stiffer than those with more elongation and keep their original dimensions during use. A low elongation value results in easy tear while a high elongation value causes leather goods to become deformed very quickly or even lose usability [9].During stitch tearing strength test, the force exerted is essentially perpendicular to the specimen and fibres. Stitch tear strength test provides information about weak points caused by possible defects of fabrication.Tearing strength test is carried