Abrasive (Sand) Blasting

Abrasive (sand) blasting is the process of forcibly propelling a stream of abrasive material against a surface under high pressure to smooth or polish a rough surface, roughen a smooth surface, shape a surface, or remove surface impurities. It consists of pressurized fluid, typically compressed air, that is used to propel a high-velocity stream of blasting material, often called the media, to clean or etch the surface. Abrasive blasting is commonly known as sand blasting since silica sand was originally the only used material as the abrasive; however, there are now various media used in the process, some more abrasive than others. The most common include:

Silicon sand or silica dioxide: This was a commonly used method of smoothing, shaping, and cleaning a hard surface, because sand particles are nearly identical in size and the edges of the particles are sharp, making this type of grit efficient in abrasive blasting. However, this kind of abrasive blasting is no longer a popular choice as respirable dust from silica sand and other abrasive materials pose a risk to the lungs.

Soda: A much milder form of abrasive blasting that uses baking soda or bicarbonate of soda in the blasting process. It’s a non-destructive method that is ideal on delicate materials that may be destroyed by tougher abrasives.

Steel grit: A variation of abrasive blasting that, as its name suggests, uses steel to leave a smooth finish. Steel grit is often preferred due to its fast cutting nature.

Glass bead: Applied at high pressure, fine glass beads are used to remove surface deposits and create a matte and satin finish. This is because this grit has very fine materials that polish the surface of the object being sandblasted.

The type of blasting media used depends on the desired effect. Because blasting media come in a wide variety of density, hardness, shape, and particle size, it’s important to match the right type of abrasive media to both the job at hand, and the method of delivery.

Abrasive (sand) blasting is used in many industries, since the varying media can be applied to a range of hard surfaces, including metal, stone, concrete, wood, tile, glass, and more. When surfaces such as metal are blasted to desired effect, they are often refinished or treated after the blasting to prevent rust and add a protective coating.

Abrasive (sand) blasting has two dominant cleaning standards, ISO 8501 and the SSPC/NACE. ISO 8501 is a pictorial standard showing the appearance of different rust grades at various levels of cleanliness, although it also contains text descriptions of the cleanliness levels. ISO 8501 ranks cleanliness levels in order of increasing work required. The SSPC standards are text descriptions, not pictorial, although they are accompanied by visual guides with photo references. SSPC/NACE numbers them in reverse order, by increasing surface cleanliness.

Abrasive (sand) blasting can present potential risks for operators’ health and safety. Some abrasives like silica sand can have varying degrees of hazard, while the operation itself can cause possible injury. In the U.S., the Occupational Safety and Health Administration (OSHA)  mandates engineered solutions to potential hazards. There is a wide range of National Institute for Occupational Safety and Health (NIOSH) guidelines and OSHA regulations addressing many aspects of abrasive blasting in order to consistently perform the task safely.


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