Application of central composite design to model the color yield of six diazo direct dyes on cotton fabric

This paper describes the modeling of the color yield of six direct diazo dyes on cotton fabric through central composite design, which is an efficient experimental design. The factors chosen for the model were dye concentration, electrolyte (sodium chloride) concentration, dye bath temperature, dyeing time, and liqor ratio. Five levels were considered for each factor. Color yield (F_k ) was taken as the response. Box–Cox transformation was employed to optimize the models. Each dye was represented by a model. The models showed a good fit. Finally a series of conditions of the factors leading to optimum response (F_k ) were identified.