Varanasi, also known as Benares or Kashi, is a city on the banks of the river Ganges in Uttar Pradesh. It is famous for its socio-economic and religious importance all over the world. The city is equally well known for brocade-weaving which is a cluster based activity and is scattered all over Benaras and some adjacent districts. In the weaving communities of Varanasi, every small house, every street, every open space is taken up by men busy with kilometres of thread. The quality of its silk fabrics is considered the most refined in the country and a must as marriage gift.
Any yarn undergoes a pre-treatment process that is carried out with boiling soap water to increase pliability and give the saree smooth and shinier texture. It is then bleached and dyed, giving the yarn its intended color, crucial to its ultimate use. Usually, dyeing is done manually with acid dye.
For more details: http://dsource.in/resource/weaving-craft-varanasi