Ecological dyeing of modified cotton fabric with natural cochineal dye

The influence of cationization during mercerization and pre-mordanting to the dyeing of cotton fabric with natural dye from Dactylopius coccus was researched in this paper. The bleached cotton fabric as well as cationized with Rewin OS were pre-mordanted using iron(II) sulfate heptahydrate (FeSO4·7H2O). For the characterization of surface changes after cationization and pre-mordanting, electrokinetic analysis on SurPASS electrokinetic analyzer was performed. Afterwards, fabrics were dyed with natural cochineal dye with and without the addition of an electrolyte, NaCl. For the purpose of determination of dye exhaustion, the analysis of dye solution was performed on the UV/VIS spectrophotometer Cary 50 Solascreen. Spectrophotometric analysis of the samples through phases of modification of cotton fabric was performed using Datacolor 850 spectrophotometer, measuring spectral characteristics from which was determined whiteness degree, color parameters, K/S and color fastness dyed fabric. Comparing cationized and non-cationized cotton fabrics, cationized samples showed better absorption abilities and color fastness. Using electrolyte at untreated cotton fabric improved the process of dye absorption. However, when cationized, usage of electrolyte is not necessary, what makes this process more environmentally friendly. Additionally, high exhaustion of natural dyes also extends the color palette.