Leathers which are used for the manufacturing of different types of bag are known as bag leather. Mostly these are chrome or vegetable tanned from lower grade raw stock having thickness 1.0-1.5 mm (or above for some particular article).Combination tanning is carried out with a combination of chrome, vegetable, synthetic or other tanning agents to improve the fullness and firmness and some other desire properties of shoe upper. The main combinations are semi-chrome and chrome-retanned leather. Leather is first tanned with vegetable and then retanned with chrome tanning agent is semi chrome retanned leather. Chrome retanned leather is softer and flexible and mostly used as shoe uppers.
PROPERTIES OF BAG LEATHER
- The physical appearance of finished leather should look attractive with clear grain.
- The leather must possess a soft and mellow ‘handle’ with fine and tight ‘break’ on the grain. The must be stable against repeated tensile and compressive strains and bending.
- The leather must possess high strength properties i.e. tensile strength, stitch tear strength, split tear strength, elongation at break etc.
- The leather must possess the hygienic property of being permeable to water vapor and air.
- The finish on the leather should have high adhesion and must be durable against wet and dry rubbing.
- Should be highly color fast.
- Should have dry and wet rub fastness.
THE MAIN REQUIREMENTS OF IDEAL BAG LEATHER:
AESTHETIC APPEAL
The leather should have elegant attractive appearance. Elegant appearance requires that the grain surface must be distinguishable from that of a leather substitute and colors, gloss and grain appearance should be attractive and appeal to the buyers of the bag. The leather should retain the colour, should not stain wearer's clothes and should have ability to take polish. Not only looks but also the feel of the leather by touch in the bag are important.PHYSICAL PROPERTIES
The most important requirements for bag leather are good adhesion (wet and dry) rub fastness and high temperature performance during plating, hot air drying and lasting. Strength and stretch of upper materials used in shoe making are good guides for their suitability. Low strength and stretch of upper leather and consider unsuitable for use as shoe uppers.
The important physical properties of upper leather which determine its suitability use in shoe making are:
- Tensile strength
- Stitch tear strength
- Split tear strength
- Elongation at break
- Distension at grain crack
Modern worldwide leather market is now a days very fond of bag leather. Finished leather is also an intermediate product. Which serves as a raw material for finished leather is therefore, fashion driven, requiring more responsiveness to the market, whereas crust leather is more a commodity type product. Bangladesh currently exports leather bags to Europe and Japan.
As production capacity in finished leather and leather goods is developed in Bangladesh, new jobs will be acquired, and markets will be accessed. But in our country’s cow hide quality is not good for many reasons, but the lower grade raw stock can be upgraded to a higher level by using different tanning and finishing techniques.
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