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FAQ: After drying, a reactive bright lemon yellow turns in to redder and duller, what is the reason and how to prevent this? Every dyestuff will appear in different tones under different pH conditions. If for example, the dyed material is dried under alkaline condition, due to the addition extra alkaline hydroxyl group, the chromophore of the dyestuff gets destroyed and the natural tone of the dyestuff changes. So a bright lemon yellow, you match in the lab becomes redder and duller in the bulk dyeing. Similar tone changes you can realize in many shades due to the influence of pH and proper control over pH in the drying stage minimizes these problems. |
