RESIST EFFECTS IN BALL BLAST FINISH FOR GARMENTS

Uno Specialities Pvt. Ltd.
A-123, Amar Gian Complex, L.B.S. Marg, Thane (W)- 400601

By
R.Y.Churi & Suyash Sule

Garment processing industry, as it is driven by fast changing fashions and styles, has to be highly dynamic and flexible in working. A processor is constantly on look out for novel results in his products.

Denim goods can be decolorized locally or all over to various degrees for fancy effects. This is feasible primarily due to two reasons: a) The dyes used are easily subjected to fading) The dyes are present mostly on the surface part of fibers, (Ring dyed effects.).

The required decolorization can be achieved by various means such as:
1) Mechanical abrasion, eg.by sand blasting, or tumbling along with pumice stones.
2) Chemical discharging through oxidation by hypochlorite or potassium permanganate
3) Enzymes- By reducto-oxidation of indigo, eg through laccase, or by surface etching of fibers,by action of Cellulase.
4) Thermal- action of laser beams.

In practice, often combinations of these means may also be employed to achieve various effects through constant improvisations. Ball Blasting as known in local trade is one of such processes. It is currently very popular one giving certain fashion styles highly in demand.

It involves surface application of sodium hypochlorite slurried with calcium carbonate powder, using thermocole spheres as mechanical medium.

The final visual effects can be varied by changing diameters of balls, concentration of chemicals, conditions or time of treatment. Over and above this, localized application some hypochlorite resisting agents such as KNOVEL R can generate attractive patterns. The desired patterns can produced either by application by brush or by spraying or by screen-printing. The drying of goods after this is somewhat critical as the film has to adhere firmly onto the surface. Excessive atmospheric moisture or inadequate drying can spoil the effects, due to bleeding or smudging. Sometimes to overcome the uncertainties, mild tumble-drying is resorted to after preliminary drying at room temperature.

The thermocole balls are available in dia 3 mm to 58-65 mm .For overall uniform effects, 3mm dia balls are preferred. Sodium hypochlorite should be with around 120gpl active chlorine; calcium carbonate could be of commercial grade.

Denim garments, trousers etc, in lot size of 40 pieces are first desized using 0.5% (w/w) UNODESIZE at 500 c, 20 min, at pH 5.5. This is followed by biopolishing treatment with BIOZYME 0.5 –1.0% at pH 4.5 for 45 min at 50-550c, using normal drum washers.

The required application of KNOVEL R is carried out in predetermined patterns on well-dried garments as described earlier.

Finally the ball blast treatment is given in a wooden drum rotating at 30-35 rpm. In first stage, 4-5 kg thermocole balls of 3mm dia, 2 ltr of sodium hypochlorite bleach and calcium carbonate powder 1.5 kg are mixed so as to form uniform coating of chlorinating slurry on surface of balls. The garments pretreated as above and dried are then introduced; whole mass is rotated for 30-40 min at room temperature.

At the end, the goods are washed with water, dechlorinated with a mild hydrogen peroxide treatment and washed thoroughly preferably in presence of a peroxide killer like NEUTRASCAN PK 0.1%.

The garments are to be finished on the basis of customers’ requirements which can change from time to time .As a broad outline, it may be mentioned that for dry waxy feel, products like EXSOFT 1.0%-1.5% (OWG) and for internal, body breaking softness, INNERSOFT 1.0%-1.5% (OWG) would give satisfactory results.

The products mentioned above are from M/S Uno Specialities Pvt. Ltd. The information given herein is only introductory in nature. For further details, please contact our Technical Service Department.
Email: unospecialities@vsnl.net
Phone: 022 25471822