Sandblasting involves propelling an abrasive media (not necessarily sand) towards a surface with the intention of smoothing or cleaning it. You can think of the process as using a high-pressure hose to clean an exterior wall but instead of water, the medium is composed of solid particles and air that are mixed in a chamber and propelled by air pressure.
Unlike smoothing with a sandpaper, corners and nooks will not be a problem when sandblasting. It is, however, similar to sandpapers in that a rougher grit can scratch away more material and a finer grit can be used for polishing.
Different abrasive media used in sandblasting are discussed briefly below.
This synthetic material is a gentle medium that is useful for blasting without causing depression or damaging the surface you are blasting.
Gentle mediums are recommended when you are unsure if the material you are blasting will be destroyed by the blasting medium. This can be used in delicate procedures such as removing paint from soft wood or removing coatings from printed circuit boards.
There are other synthetic materials that can be used as gentle media such as corn starch and magnesium sulphate.
Agricultural waste such as crushed walnut shells are also useful gentle mediums that will not damage the underlying material and are useful when cleaning brick or stone or removing graffiti.
Other agricultural materials are crushed fruit kernels and granular abrasives manufactured from crushing the dense woody ring of a corn cob. These materials are biodegradable and will have a minimal environmental impact.
Silica sand is the most common mineral abrasive. At the microscopic level, these sand particles have a lot of edges that are highly abrasive that can blast any surface. However, it is sometimes too abrasive and destroys delicate materials.
This can also cause lung problems from inhalation of dust released when the sand particles hit the surface and break. An alternative mineral abrasive is garnet which does not produce a lot of dust.
Fine glass beads are very fine materials that polish the surface being blasted. This can be used for matte and satin finishes in cabinets. An alternative to this is recycling glass bottles into crushed glass grit which also does not damage the surface and can be used to clean calcium deposits from pool tiles or remove embedded fungus on walls.
Another recycled material; plastics do not indent, warp or destroy sensitive material so plastic beads are used in aerospace and automotive industries such as sandblasting plane fuselages or car panels. These can be found as acrylic, polyester, urea, or melamine plastic blasting media and are recyclable after use.
Impurities during smelting of copper float on top of the molten metal as slag. When quenched, these produce angular granules that can be used as blasting media. Some process byproducts such as nickel or coal slag can also be used as abrasives.
Metallic media like steel grit are very abrasive because of their sharp edges and cannot only remove paint and rust from metals but also prepare the surface by etching them so paints and other materials can easily adhere.
As the metal hits the surface, the particles lose their edge. These can be reused as steel shot and used for less aggressive blasting.
Silicon carbide or carborundum is an engineered abrasive and is the hardest medium available. This is commonly used for metals because of its polishing effects. This is a highly-abrasive medium because as the particles hit the surface and break, it exposes new sharp edges.
As you can see above, there can be different sources of blasting material such as minerals, process byproducts, and even agricultural waste. Of course, when blasting, the most important factor is the capability of the material to strip the surface or its “cutting action”. Some materials like sand are very aggressive while some like soda are much gentler.
Choosing the right sandblasting medium can be difficult not just because of the many different materials but also other intricacies within the same material. For example, if you opt to use sand you will still have to decide which grade or grit size you will use.
If you do not have any you professional experience in sandblasting, you can experts to do the job. By doing so, you can avoid making mistakes and possibly damaging the surface you plan on.