Reaktivfärben

Reaktivfärben is a dyeing process that utilizes reactive dyes. These dyes form a covalent bond with the fiber molecules, resulting in excellent colorfastness to washing, light, and rubbing. This chemical reaction occurs when the dye molecule, under specific conditions of pH and temperature, attaches directly to the hydroxyl or amino groups present in fibers like cotton, linen, rayon, and wool.

The process typically involves immersing the fabric in a dye bath containing the reactive dye, an alkali (such as sodium carbonate) to promote the reaction, and sometimes salt to increase dye uptake. Once the dyeing is complete, the fabric is rinsed thoroughly to remove any unfixed dye. The covalent bond ensures that the dye becomes an integral part of the fiber structure, making it very durable.

Reaktivfärben is widely used for dyeing cellulosic fibers due to the high reactivity of the dye with the hydroxyl groups of cellulose. It is also applicable to protein fibers like wool and silk, where the dye reacts with amino groups. The resulting colors are often bright and vibrant. The environmental impact of reactive dyes is a consideration, with efforts focused on optimizing dye exhaustion and minimizing unfixed dye in wastewater.