What is Ice Wash or Snow Wash?
Ice wash gives indigo jeans sharp contrasts. The process was created in Italy and was patented in 1986. This finish provides jeans with sharp contrasts in tonal color. This is also known as acid wash or snow wash. This is achieved by dry tumbling with pumice stones soaked with bleaching agents to produce a ‘snow’ pattern effect on denim. Stones are used to deposit a chemical on garments to strip off the color. This chemical deposit removes color only from the outer surface of the garments and produces a frosted appearance. Indigo and selected sulphur dyes are the most popular candidates for this procedure.
In the case of an ice wash, in which more than half the dye is removed during washing, one can use a lighter shade of fabric, which will cut the process time, chemical consumption and effluent load. It will help the garment processor work more economically and with minimum error.
Working Process of Ice Wash or Snow Wash:
1. Soak stones in solutions of potassium permanganate for 1-2 hours. Concentrations ranging from 1.5% to 5% are being used commercially. (5% to 10% sodium hypochlorite can be substituted.)
2. Stones should be drained of excess liquor. This can be accomplished by placing stones in net or mesh fabric prior to soaking. Then the stones can be removed and the excess drained off. Another alternative is to place the stones in a rotary tumble machine along with “waste” fabric and tumbling for several minutes to remove the excess solution. A third alternative is to use any number of the pre-soaked stones or materials available from suppliers. These are available in many different shapes with varying levels of chemical and other additives that produce different effects. Trials should be conducted to determine the best method for achieving desired effects.
3. Place stones and garments in machine (garments should be scoured and/or desized and dry or slightly damp).
4. Tumble for 10-30 minutes or until desired effects are achieved. Results are dependent upon dyestuff, fabric, concentration of chemicals, stones, additives, and equipment.
5. In some cases, the stones can be reused for another load before resoaking, depending upon their porosity. It is advantageous to transfer the garments to another machine for washing, minimizing the number of machines used for the corrosive process of ice washing.
6. If potassium permanganate is used, manganese dioxide will form (a brown/orange color) and must be removed by treatment with sodium bisulfite, hydroxylamine sulfate, or acidified hydrogen peroxide as the reducing agent. Fill the machine with water and add 1-5 g/l of the reducing agent. Heat to 50ºC and run for 20 minutes. The process is normally repeated twice to ensure complete removal of the manganese dioxide. When sodium hypochlorite is used, the residual chlorine should be removed with sodium bisulfite or hydrogen peroxide. Adding jeans to machine already charged with after washing chemicals will increase contrast.
7. Rinse well.
8. Repeat step 6 if necessary.
9. Apply softener.
10. Tumble dry.
11. Press, if required.
The selection of sodium hypochlorite versus potassium permanganate depends upon the dyestuff and desired effect. Also, consideration must be given to the safety aspects of handling either chemical.
Ice Wash Effect Finishing on Denim Garments:
In this particular finishing, the stones act as vehicles to deposit chemicals on the garments so as to strip the indigo color from the surface of the denim fabric. The surface chemical deposition will remove the color from the outer surface of the garment and deliver an attractive elegant, frosted appearance. Indigo and sulphur-dyed denim fabrics are normally applied for the ice wash effect.
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Founder & Editor of Textile Learner. He is a Textile Consultant, Blogger & Entrepreneur. He is working as a textile consultant in several local and international companies. He is also a contributor of Wikipedia.
