Абразивоструйная очистка: всё, что нужно знать

Abrasive blasting has been used for surface preparation for well over a century and is still the reference method for cleaning steel before coating. It also has well-known drawbacks, from silica dust to containment and waste. This article explains what abrasive blasting is, what it is used for, its health risks, and when MontiPower® power tools are a practical alternative for spot repair and maintenance.

What is abrasive blasting?

Abrasive blast cleaning is the process of propelling abrasive particles at a part or surface at high speed. Most often the particles are carried by compressed air (dry blasting) or by air and water (wet or vapor blasting); centrifugal wheel blasting throws the media mechanically instead. Blasting is used to clean, treat or texture many kinds of surfaces, most of all steel and other metals.

The process is often called sandblasting, because silica sand was historically the most common abrasive. Strictly, sandblasting is only one type of abrasive blasting. Today a wide range of media is used instead, such as steel grit and shot, garnet, mineral and metal slags, glass beads and plastic media. The term grit blasting usually refers to blasting with angular media such as steel grit or garnet. Broadly speaking, all these methods work the same way: the medium strikes the surface with great force. Our overview of the 10 types of abrasive blasting compares them by profile, media and containment needs.

What is abrasive blasting used for?

The impact of the abrasive removes a layer from the surface. This hammering effect removes rust, mill scale, paint and other coatings. It not only cleans the object but also roughens the surface, creating the anchor profile a new coating needs to adhere. That is why abrasive blasting is the method the main cleanliness standards are written for: ISO 8501-1 Sa grades and the AMPP (SSPC/NACE) blast cleaning standards such as SSPC-SP 10 (near-white metal) and SSPC-SP 5 (white metal).

Blasting is fast on large, open areas and remains the right choice for new-build steel in a blast shop or yard. Its cost and complexity lie in the set-up: compressor and blast pot, abrasive supply, containment, cleanup and disposal of spent media mixed with removed coating.

What are the health risks of abrasive blasting?

The use of sand in blast cleaning has declined because of its health risks. When silica sand is blasted against a surface, the grains shatter into very fine particles. The finest fraction, respirable crystalline silica, is small enough to reach deep into the lungs, where it can cause silicosis, a debilitating, irreversible and sometimes fatal lung disease, and it is also linked to lung cancer.

For that reason several countries restrict or ban silica sand as a blasting medium:

• In the Netherlands, blasting with a material that contains more than 1% quartz or other free crystalline silica is prohibited (Working Conditions Decree, article 4.61).
• According to NIOSH, using sand for abrasive blasting has been outlawed in the United Kingdom since 1949.
• In the United States, NIOSH has recommended since 1974 that silica sand be banned for abrasive blasting, and OSHA's construction silica standard (29 CFR 1926.1153) sets exposure limits and control requirements for work that generates silica dust.

Silica-free media reduce the silica hazard but not every risk. Blasting old coatings can still release lead, chromates and other hazardous dust, and the operator works with high-pressure equipment, noise and a large volume of spent media. More on this in what are the dangers of sandblasting?

Alternative tools to abrasive blasting: the Bristle Blaster® and MBX®

The Bristle Blaster® and MBX® from MontiPower® are hand-held rotary tools with patented wire bristle belts. For smaller and hard-to-access areas, they remove the need for loose abrasive altogether: no blast pot, no media supply and no spent abrasive to collect. The two tools serve different jobs:

• Bristle Blaster®: for steel surface preparation before protective coating. The bristle tips strike the surface and create an anchor profile comparable to blasting: in documented tests, cleanliness comparable to ISO 8501-1 Sa 2½ / SSPC-SP 10 and a 65–85 µm Rz (2.6–3.3 mil) profile on standard steel. Results vary with steel grade, rust grade, belt and technique.
• MBX®: for removing rust, paint, underseal, sealants and adhesives from car body panels and similar thin substrates, without heat or warping. MBX® coarse and medium belts leave a finish similar to sandblasting on body panels, but MBX® is not designed for preparing structural steel to a coating specification.

Grit-free does not mean dust-free: the rust and coating removed from the surface still become particles, so extraction and appropriate respiratory protection are still required. See the alternative to sandblasting for a direct comparison.

How do MontiPower® bristle tools work?

The Bristle Blaster® and MBX® are hand-operated tools fitted with a rotating belt of specially designed wire bristles. On the Bristle Blaster®, the hardened, forward-angled bristle tips are briefly held back during each rotation by the accelerator bar. Released from behind the bar, the tips strike the surface with kinetic energy comparable to grit blast media and immediately rebound. That combination of impact and retraction removes corrosion and leaves the characteristic crater-like micro-texture of a blasted surface.

Speed is controlled rather than maximised: the Bristle Blaster® Ultimate Cordless, for example, runs at 2,200 rpm, and the MBX® drives idle at 3,200–3,500 rpm. If a bristle tool runs too fast, the tips scrape across the surface instead of striking it and fail to generate the required roughness. The grit blasting vs bristle blasting comparison shows how the results compare on cleanliness, profile and containment.

Alternative to blasting in different sectors

Because no loose abrasive is used, the tools suit work where containment or cleanup would dominate the cost of blasting: spot repairs, weld seams, flanges, in-service equipment and confined spaces in the maritime and industrial sectors. Public infrastructure is a good example. Blasting bridges, rail and highway structures is time-consuming and labor-intensive, often under pressure from traffic closures, and exposes workers to fine particles and possibly hazardous old coatings. For local repairs on such structures, bristle blasting avoids the blast set-up altogether; see bridges, rail and infrastructure. For large, continuous areas, abrasive blasting usually remains the faster and more economical choice.

Frequently asked questions

What is the difference between sandblasting and abrasive blasting?

Sandblasting is one type of abrasive blasting that uses sand as the medium. Abrasive blasting is the general term and covers many media, such as steel grit and shot, garnet, slags, glass beads and plastic. Because silica sand creates respirable crystalline silica dust, its use for blasting is banned or restricted in a number of countries.

Is sandblasting with silica sand banned?

In several countries, yes. In the Netherlands, blasting with any material containing more than 1% quartz or other free crystalline silica is prohibited under the Working Conditions Decree. NIOSH reports that using sand for abrasive blasting has been outlawed in the United Kingdom since 1949, and has recommended a ban in the United States since 1974.

What is abrasive blasting used for?

To remove rust, mill scale, old coatings and contamination from steel and other surfaces, and to create the anchor profile a new coating needs to adhere. The required cleanliness is specified as a blast grade, such as ISO 8501-1 Sa 2½ or SSPC-SP 10, and the profile is set by the coating data sheet.

Is bristle blasting dust-free?

No. Bristle blasting uses no loose abrasive, so there is no blast media to contain, recover or dispose of. The rust, scale and coating removed from the surface still become particles, though, so extraction where available and respiratory protection based on the site risk assessment remain necessary, especially on old coatings that may contain lead or chromates.