Sand Blasting

Sand blasting is a mechanical process in which localised abrasion or colour change on the denim garment is created. The process involves blasting an abrasive material in granular, powdered form at a very high speed and pressure through a nozzle, on certain areas of the garment such as knees and elbows. The treated surface shows distressed/abraded/used look.

The common blasting materials used are sand and metal granules. During sand blasting process, denim garments are first subjected to stone washing to the desired degree of washing and are then sand blasted. A solution of sodium hypochlorite or potassium permanganate is often sprayed on the desired area of the garment in order to obtain the same look. The garment is then neutralised, rinsed, softened and dried. Sand blasting is a water free process and, therefore, no drying is required.

Health problems

Sand blasting removes the dark indigo from a denim garment giving it a popular pre-worn look. This process involves smoothing, shaping and cleaning a hard surface by forcing abrasive particles across that surface at high speeds using special types of sands. These are sprayed onto the selected parts of the denim garments at high pressure through air compressors to remove colour from those areas to create the desired design.

Sand blasting can be done manually or mechanically. The mechanical process encloses the sand and dust particles in blasting cabinets and is–if used correctly–therefore less hazardous for the operating workers. However, manual sandblasting is preferred by factories as it is cheaper because it does not require investment in advanced and expensive industrial equipment. Sand blasting also costs less than other fading methods (like hand sanding) which are more labour intensive. Whilst sandblasting to achieve a worn look on denim is a relatively new phenomenon in the clothing industry, similar methods have been widely used in mining and building industries for many decades and the link between the use of sand blasting and the risk of silicosis has long been acknowledged. It was the high health risks associated with manual sand blasting process that prompted regulation of the technique in the Europe in the 1960s. Sand blasting can expose workers to extreme health hazards and can cause death within months or years of starting work as a sandblaster. Sand blasting using natural sand is especially problematic because workers inhale crystalline silica dust particles during production, causing serious damage to the respiratory passages. These particles are so tiny that they are invisible to the naked eye.

The body is unable to expel the silica particles, causing diseases such as silicosis. The particles penetrate the pulmonary alveoli and the connective tissue, gradually impairing lung capacity and the workers’ ability to oxygenate blood. Symptoms include shortness of breath; as the disease develops, this is common even when resting. This puts additional strain on the heart, eventually leading to death. However, the progress of silicosis can be slowed if symptoms are diagnosed at an early stage.