Effect of dye bath pH in dyeing of cotton knitted fabric with reactive dye (Remazol Yellow RR) in exhaust method: impact on color strength, chromatic values and fastness properties

The significance of textile coloration is inevitable as coloration is a critical process and it can be affected by several parameters i. e. time, temperature, pH, and liquor ratio (M:L). This research reveals the behavior of different dye bath pH (2 to 12) on the basis of spectrophotometric characteristics and colorfastness using the most useable brand of reactive dye in Bangladesh i. e. Remazol Yellow RR. Earlier researches were performed on the basis of other coloration controlling factors i. e. temperature, time and liquor ratio (M:L) where pH acts as the dependent variable. However in this study, pH was taken as an independent variable where lower pH (2, 4 and 6), medium pH (8 and 10) and higher pH (12) were taken into consideration for verifying the dyeing performance. Meanwhile, the mentioned pH was achieved by adding acetic acid, soda ash and caustic soda respectively. In this study, the impact of pH is analyzed on the basis of color strength, chromaticity, hue angle, CIELAB color space, spectrophotometric image, reflectance percentage and color fastness tests i. e color fastness to rubbing, color fastness to wash, color fastness to perspiration, color fastness to light. Gradually elevated pH boosts up the color strength and chromaticity, at the same time downgrades of hue angle results orangish tone in the dyed fabric. Even more, the lightness of dyed fabric decreases and redness rises with the increment of dyebath pH which results in orangish red darker tone of dyed fabric. Consequently, fabric dyed at acidic dye bath pH exhibits higher resistance in case of color change and color staining from the dyed fabric and multifiber fabric respectively and vice versa.