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Product Introduction I - Cellesh 200/300 We have recently had an experience regarding how to minimize the backstaining of reactive dyes on white backgrounds which may be of interest to you. Reactive dyes backstaining is a common problem in the washing stage after coloured cotton fabric or yarn has been incorporated into garment with white or light coloured sections. It is especially prevalent in garment laundering factories. We have done some experiments in our laboratory and found that general anionic & nonionic detergents cannot prevent this blackstaining from occurring. The most common way of addressing this problem is by using a chelating & dispersing agent to minimize the effect but different types of chelating & dispersing agents and different amounts of the agent would have different levels of success. For generally, alkali type chelating & dispersing agents are better than acidic types. For example, in our product range, Cellesh 200 is better than Cellesh 300. Before doing the experiment, we expected that acidic types would better than alkali types as the low pH will lower the substantively of reactive dyes. However, the result was just the opposite and shows that theory is no substitute for experience.   Diagram 1     Furthermore, the amount of chelating & dispersing agent should be carefully controlled. Our experiments indicated that 0.5 g/l of Cellesh 200 is the optimal amount. At the beginning, we tried 1 g/l, 2 g/l and 3 g/l. The best result is 1 g/l. Then we tried 0.5 g/l and the result is ever better than 1 g/l.   Diagram 2           For the washing temperature, low temperature is better than high temperature. Don't use any temperature higher than 50C. This is because the higher the temperature, the more likely the dyes dissolved in the washing water will stain the whole garment or fabric. Furthermore, we found that the results of adding 0.5 g/l non-ionic detergent together with the chelating & dispersing agent is better than that of using the chelating & dispersing alone. This is because non-ionic detergent has very good emulsifying and cleaning properties but low penetrating properties. This further prevents the dissolved dyes from penetrating into the fibre. To reduce backstaining even further, a large amount of cool water should be used to rinse the fibres quickly a few times before washing. The short cool rinse provides no condition and media for the dissolved dyes to stain the fabric and part of the dissolved or excess dyes will be removed. In this way, there will be a lower concentration of excess dyes remaining in the fibre to be carried to the washing stage. Any comments or queries you have on the above would be welcome . Look forward to receiving your views. Thank you.