Abstract

The dyeing potential of roselle (Hibiscus sabdarifa) extract variously extracted by boiling, steeping and ethanol solvent were evaluated with three dye fixatives (potassium aluminum sulphate (alum), tannic acid, and citric acid), to study their effects on cotton (100%), stone silk (60% silk:40% polyester) and polyester (100%) fabrics. Colourfastness to sunlight, washing, perspiration (acid and alkali) and rubbing (crocking) were studied on the individual fabrics as 1 × 4 factorial involving three dye extracts (1 dye source × three extraction methods) and three dye fixatives plus a non mordanted control in a completely randomized design (CRD) of three replications. Data on degree of fastness were generated as scores through 1 (excessive colour fade or stain) to 5 (no colour fade or stain) using Gray scale and fastness test rating scale (FTRS) evaluation instruments. Data were analyzed using descriptive statistics (means and standard deviations) and general linear model for factorial experiments of statistical package for social sciences (SPSS) version 16.0. Three null hypotheses were tested using analysis of variance (ANOVA). Treatment means were compared using Scheffe’s test at 0.05 probability level. Findings include: Roselle calyces extracts showed reasonable colourfastness on cotton prototypes. The effects of dye extraction procedures did not significantly differ (p>0.05) on the colourfastness of cotton prototypes to sunlight (p=0.33), washing (p=0.39), alkali perspiration (p=0.06) and dry rubbing (0.59). The effects of mordant/dye fixatives did not significantly differ (p>0.5) on the colourfastness of cotton prototypes to washing (p=0.95) and rubbing or crocking (p=0.68), but differed significantly (p<0.05) on colourfastness to sunlight (p=0.00), acid perspiration (p=0.00) and alkali (p=0.00). Tannic acid and alum mordant were the source of difference. Roselle calyces extracts exhibited much to excessive fade and stain of colour and poor fastness to all parameters tested except rubbing fastness.

Key words: Fabric, colourfastness, dye fixatives, dye extraction, Roselle.