Prior to the production of synthetic dyes, Indigo was the most important and the most used natural dye, and the importance of this natural dye was reduced by the production of synthetic blue dyes and synthetic indigo dyes. In recent years, due to the disadvantages of synthetic dyes, natural dyes have re-emerged, especially with regard to the dyes used in clothes that are directly in contact with the skin. Iranian carpet and jean industry are the two main markets of this dyes in our country. Iranian woad is the main source of natural indigo which has been out of markets for years due to the low efficiency of existed extraction methods hence, applying new extraction method and evaluating the dyes are in concept. In this research, extraction method regarding optimizing the best procedure for the production of two main components of indigo dye namely, blue indigo and red indigo (indigorubin) and their production yield are studied. At first, an attempt was made to find a method for the production of high-efficiency Indigo dyes in order to reduce production costs; then, different conditions of the reaction ambiance were determined to identify and control the production of each dye. Also, the two dyes were separated from each other and identified and then the spectral analysis of each dye was examined separately. Subsequently, the effect of different conditions on the behavior of each dye, the determination of the concentration of each dye separately in unpurified dye and the examination of the two-dye differences were evaluated. Wool yarns were dyed with produced to obtain different colors of blue, purple. Results showed that extraction in 80°C following with oxidation in blowing extra air at 60°C yield the highest dyestuff extraction. It is found that oxidation in alkaline media increases the percentage of blue indigo vs. red indigo. The absorption coefficient for blue indigo and red indigo obtained at 0.1795 and 0.4865 respectively.
