Abstract
The leuco potential of eight sulfur dyes and the reduction potential of reducing agents were exa-mined in various conditions in terms of -Ec (mV) that is the value of platinum electrode to calomel electrode.
The following main results were obtained-
a) The reduction power under dyeing condition decreases in the following order. Thiourea dioxide>sodium hydrosulfite>alkali metal sulfide. The stability of alkali metal sulfide are larger than the value of thiourea dioxide or sodium hydrosulfite.
b) It was found that the leuco potential of sulfur dyes derived by thionation with polysulfide of the indophenoles is lower than the values of dyes derived by sulfur melting.
c) The control of dyebath is possible with attention on pH and temperature as in the case of vat dyestuff.
