Topping & Bottoming
Bottoming:
In this case another dye is applied before dyeing with indigo. First the warp sheet is dyed with sulfur and then it is washed and then dyed with indigo.
Topping:
In this case the warp sheet is dyed with indigo in start and then it is washed and then it is dyed with another dye (normally with sulfur).
Bottoming indigo Topping:
In this case the warp sheet is firstly dyed with some dye and then after washing with indigo and then after washing with other dye like sulfur.Washing is done after each bath in order to remove unfixed dye. Dyeing of indigo occurs at low temperature and that of sulfur at high temperature. Firstly the warp sheet is dipped in the dyeing liquor and then airing is done in order to do fixation as indigo and sulfur dyes are in reduced form in liquor than they are oxidized by giving air. Which is necessary because if airing is not proper than immature oxidation occurs. For this purpose an airing zone of about 40 m is provided after each bath. The airing process is also known as dwelling time.
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