Warning: No part of this site may be reproduced, stored in a retrieval system or transmitted in any form without the prior permission of the website owner is strictly prohibited.

7TH CLASS 3RD CHAPTER WOOL --- ఉన్ని నిచ్చే జంతువులు

              7TH CLASS 3RD CHAPTER WOOL 

Wool is the fibre derived from the fur of animals of the Caprinae family, principally sheep and goats, but the hair of certain species of other mammals such as alpacas and rabbits may also be called wool. This article deals explicitly with the wool produced from domestic sheep.Most of the fibre from domestic sheep has two qualities that distinguish it from hair or fur: it has scales which overlap like shingles on a roof and it is crimped; in some fleeces the wool fibres have more than 20 bends per inch.The quality of wool is determined by the following factors, fibre fineness, length, scale structure, colour, cleanliness, and freedom from damage. For example merino wool is typically 3-5 inches in length and is very fine. Wool taken from sheep produced for meat are typically more course, larger diameter, and fibres are 1.5 to 6 inches in length. Freedom from damage refers to the structure of the wool when it is removed from the sheep and implies that the wool is clean, white, long, fine, and free of defects from the environment.Both the scaling and the crimp make it possible to spin and felt the fleece. They help the individual fibres attach to each other so that they stay together. Because of the crimp, wool fabrics have a greater bulk than other textiles and retain air, which causes the product to retain heat. Insulation also works both ways; Bedouin and Tuareg use wool clothes to keep the heat out.The amount of crimp corresponds to the fineness of the wool fibres. A fine wool like merino may have up to a hundred crimps per inch, while the coarser wools like karakul may have as few as one to two crimps per inch.Hair, by contrast, has little if any scale and no crimp and little ability to bind into yarn. On sheep, the hair part of the fleece is called kemp. The relative amounts of kemp to wool vary from breed to breed, and make some fleeces more desirable for spinning, felting or carding into batts for quilts or other insulating products.Wool is generally a creamy white colour, although some breeds of sheep produce natural colours such as black, brown (also called moorit) and grey.Wool straight off a sheep contains a high level of grease (thus "greasy wool") which contains valuable lanolin. In this state it can be worked into yarn or knitted into water-resistant mittens or sweaters, such as those of the Aran Island fishermen. The grease is generally removed for processing by scouring with detergent and alkali. Lanolin removed from wool is widely used in the cosmetics industry.After shearing, the wool is separated into five main categories: fleece (which makes up the vast bulk), pieces, bellies, crutchings and locks. The latter four are packaged and sold separately. The quality of fleece is determined by a technique known as wool classing, whereby a qualified wool classer tries to group wools of similar gradings together to maximise the return for the farmer or sheep owner.The fibre diameter of wool varies from 15 micrometres (superfine merino) to 30 or more micrometres for the coarser wools. The finer diameters are generally more valuable.Due to high concentrations of carbon dioxide, sheep wool does not burn and is therefore also used as an insulation.


Next Post »
0 Komentar