Tuesday, August 31, 2010

Reductive Bleaching For Denim Garments - Less Rejections & Excellant Softness

A large part of denim garments are subjected to processes that make them aged or old or worn out. This aged effect is generally obtained by a hypochlorite or peroxide bleaching of the garment or by stone washing or by an enzymatic bleaching treatment with the help of cellulase enzymes. In all the above cases the garment processors land up with the following problems:
  • No uniformity in ageing or fading of shades; generally out of 100 garment pieces about 10 to 15 may got over bleached or under bleached due to the aggressive nature of the bleaching agents used.
  • Generally the bleached garments become very harsh to feel. Every time a a softening treatment is required.
  • If enzymes such as cellulase are used, they have to be deactivated to stop the process at the required stage.
But all the above said problems can be over come by your own home made Reductive Bleaching Agent.

How to make an effective Reductive Bleaching Agent?

What are the chemicals or ingrediant required for making this?

Its very simple.

Ingredients and 2  formulas:

For Making 100 kgs of Reductive Bleaching Agent -1.

  • Liquid Glucose = 850 grams
  • Non-ionic Detergent =  40 grams (100% Ethoxylate Based fatty alcohol poly glycolic ethers)
  • Ammonium Sulphate = 110 grams (You can use Ammonium Chloride, acetate, citrate)
All mixed together  gives 1kg of Type-1 Reductive Bleaching Agent.

For Making 100 kgs of Reductive Bleaching Agent -2.

  • Liquid Glucose = 830 grams
  • Non-ionic Detergent =  70 grams (100% Lauric Acid Based n-methy glucomide)
  • Sodium Citrate = 80 grams 
  • Sodium Perborate = 20 grams

Bleaching Treatment:

Treat the  the materials to be bleached with sufficient quantity of caustic soda lye so that the pH of the bath is 13 to 14 at 90°C for 15 minutes. To this bath add 0.15% to 0.2% of the above Reductive Bleaching formulation. Continue treatment at 90°C for 80 minutes.

Drain the bath. Do 1 cycle cold wash followed by mineral acid neutralization. (About 3 to 5 gpl of HCl (35%) may be used for neutralization. Go Cold wash thoroughly to ensure complete removal of mineral acid.Hydro Extract and tumble dry.

You will get uniformly aged/worn out denim garments with good soft feel.

(Try these experiments for a very small batch and adjust the recipes according to your actual requirements).

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