To improve the rub fastness of fabrics is one of the sensitive tasks in laundry business. Following are some of the possibilities described.
Of course it’s all about the quality of the used fabric but in Garment Wet Processing are some useful solutions to improve the fastness. One way could be to spray the garments before washing with a special auxiliary to deepen the color and improve the rubbing fastness, such as the Atrix system of CHT-Tübingen, Germany. This product has to be applied by spray and afterwards immediately glazed manual with a brush or rubber gloves. Subsequent put the garments in a curing oven, dry them at 80 to 90 °C and fix them at 150 °C.
Another option is to use special auxiliaries for fixing indigo dyestuff in a bath. Usually fixing agents are cationic products and accumulated to the fiber. Per temperature it will be linked to the fiber. A well known product is the Rotta Fix 1545 from ROTTA/DYSTAR which you apply in a bath with liquor ratio of 1:10 at 30 °C for 3-5 min and then heat up to 60 °C for further more 10-15 min runtime. Of course other products are available on the market but normally they are all cationic products and work more or less in the same way as above described. Important is to keep the pH slightly acid all time during process.
This could be done at the beginning of the wash process, even before desize, or at the end of a wash process. If you want to add some softener, it should be done after the fixing agent is applied. Usually the softeners are also cationic products and the fixing agent should reach first the fiber before the softener could occupy these places. But the usage of softener decreases the rub fastness, be aware of that. Especially silicon softener reduces the value of rub fastness much.
Some special fixing agents of pigment dyes leave a layer on the fabric which needs to be dried very well at 100 °C in a tumbler to show good results according rub fastness improvement. Make sure that the garments are generally dried well. But from the other side you should clean the washing machine after usage of fixing agents with one rinse before you let the drum be dry and some dried layer of these auxiliaries remain at the drum.
Also the hardness of the water can influence the backstaining behavior and there for the rub fastness. If the hardness is high the enzymes and detergents might not work well and as a result the jeans become too blue. It could be useful to run the desize and the stonewash with softwater and the other bathes such as rinses with the normal used water or to work with special ion catcher. It depends on the quality of the existent water.
Generally warm and cold rinses improve the rub fastness, rinse out as much as possible of the loosen dyestuff is the easiest way to obtain better results. Dry the garments inside out and dry them well, don’t overload the dryer, may be divide the batch in two parts.
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