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SAI International School
                                                       Class – VII

                                                 Subject – Chemistry
                                                 Topic –Animal Fibre
                                Sub-Topic – Properties and Qualities of Wool

                                                   LESSON NOTES
               Properties of wool:



               Property                                           Description
               Durability               Wool is a hard fibre that retains its nice appearance for a long
                                       time.
               Absorption of           As a fabric wool absorbs moisture from the body and retains it
               moisture.               inside its fibres. This helps us to hold body heat. Woollen
                                       garments also generate heat from the moisture absorbed from
                                       the atmosphere.
               Dye ability             Wool can be coloured with different types of dyes.


               Resistance to fire      Wool does not burn easily. When subjected to flames it
                                       smoulders.


               Chemical structure      Wool is composed of natural proteins which are biodegradable


               Insulating nature       Wool does not allow heat to transfer through it very easily. The
                                       tiny gaps present between the fibres trap air which heat up as
                                       the moisture in the centre of the fibre heats up making wool a
                                       perfect insulator.







               Quality of wool:
               The quality of wool is judged by the following factors:-
                 Wool length
                 Diameter
                 Elasticity
                 Strength
                 Durability
                 Effectiveness insulator and
                 Its ability to take up colouring dyes.


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