Effect of Modifications on Dyeing Behaviour and Tenacity of Rajshahi Silk Fabric Dyed with Reactive Brown 10 and Direct Orange 31 Dyes

An improved multivoltine variety of Rajshahi silk fabric is used as material for investigation. This fabric is degummed to remove sericin, as sericin is soluble in hot water and highly responsible for the fading of dyed silk after washing. Rajshahi silk fabric is dyed with Reactive Brown 10 and Direct Orange 31 dyes. The color of the silk fabric becomes even and bright when it is dyed with 2.0% Reactive Brown 10 and 2.5% Direct Orange 31 after 50-60 minutes at 80-100°C. To achieve fast color, the silk fabric is treated with six modifying conditions prior to dyeing and among them, comparatively better modifying conditions are selected on the basis of color fastness upon exposure to sunlight in air and wash fastness in a soap solution. The modified Rajshahi silk fabric with 30% CH₃COOH and 20% tannic acid together show better dyeing properties than modifications with other conditions and unmodified silk fabric. Direct Orange 31 shows better colorfastness than Reactive Brown 10 after exposure to sunlight in air and also after washing with a soap solution.