Sandblasting is a powerful method used in different industries to clean, smooth, and texture materials. It can help achieve the perfect finish by removing rust, preparing surfaces for coating, or just restoring an old structure.
In this guide, we are going to break down everything you need to know about sandblasting–from what it is, how it works, and its applications. We will also discuss various abrasive media, the difference between sandblasting and shot blasting, and more.
By the end, you will have a clear idea of how sandblasting helps clean and prep surfaces for the perfect finish.
What Is Sandblasting?
Sandblasting is a method of preparing surfaces by spraying abrasive materials against the surface at high speed using compressed air. It is used to clean surfaces and make smooth surfaces rough or rough surfaces smooth.
The sprayed abrasive works like sandpaper and is efficient for removing unwanted coatings like rust and paint, leaving behind a clean and perfectly textured surface. The process is widely used in different industries including construction and automotive repair.
Sandblasting is quite a versatile technique. You can use it to achieve different results depending on the type of abrasive material you choose.
Originally, the sandblasting process involved using sand particles to blast the surface. It has a coarse texture that effectively strips away unwanted imperfections. Today, other techniques and materials are used to get the desired results even though “sandblasting” is the term you will hear in everyday language. Sand might have been the original abrasive but there are other safer alternatives now. So the more correct term would be abrasive blasting.
A Brief History of Sandblasting
Sandblasting was invented by Benjamin Chew Tilghman, an American inventor. He patented the process in October 1870. Sandblasting can happen naturally when the wind blows sand particles over the earth’s surface, gradually changing the shape. The story goes that Tilghman came up with the idea after observing the effect of sand blown against windows by wind in the desert.
The method was quickly adopted in different areas including shipbuilding, glass etching, and metalworking. It drastically changed how different surfaces were cleaned and prepared. Over time, more efficient abrasive blasting techniques came up, thanks to advancements in the materials and equipment used.
Around the mid-20th century, there were health concerns about the effects of silica dust. It is a byproduct of using traditional sand as an abrasive. Exposure to silica dust particles led to cases of silicosis, a serious lung disease. As a result, industries started shifting towards safer alternatives like steel grit and glass beads.
Sandblasting Vs Shot Blasting: What’s the Difference?
Sandblasting and shot blasting are both types of abrasive blasting but they differ in how they work and what they are best suited for.
Sandblasting uses compressed air to blast abrasive materials like glass beads, sand, aluminium oxide, etc. against a surface. The process can remove paint, dust, and other contaminants. It can also create smooth finishes on materials such as glass, metal, and concrete. Depending on the blasting material used it can be aggressive stripping or gentle cleaning.
Shot blasting, on the other hand, is more aggressive and uses a mechanical wheel to spray steel grit or other metallic abrasives. The process is best suited for hard materials like concrete and steel because of how forceful it is. It is commonly used in heavy industrial applications.
Sandblasting Vs. Wet Blasting
Sandblasting (or dry blasting) uses compressed air to propel abrasive media onto a surface. It is fast and efficient and works well on different surfaces including wood, metal, and concrete. The downside is that it generates a lot of dust which can pose health risks.
Wet blasting, on the other hand, propels the abrasive media mixed with water to clean surfaces. This method is gentler on surfaces compared to dry abrasive blasting. It is ideal for delicate materials and situations where proper dust control is necessary.
Why Is Sand Blasting Important?
Sandblasting is an important process in surface preparation and finishing. It ensures a well-textured and clean surface leading to great results.
Preparing surfaces for coatings:
A surface needs to be clean and smooth before applying paint or adhesives. Removing old coatings, paint, and debris prevents peeling or premature failure of coatings. Sandblasting in automotive repair, for instance, is used to prepare the body panels before painting. This results in a flawless and durable finish.
Removing rust and corrosion from surfaces:
Rust and corrosion are common issues with metallic surfaces and they can weaken the structure over time. Abrasive blasting is an effective method of removing scaling and corrosion. It leaves the material looking as good as new and makes it long-lasting. It is especially important in cleaning marine, industrial, and construction equipment as they are exposed to harsh environments.
Removing contaminants and cleaning surfaces:
Dirt, grease, oil, and chemical residues can interfere with processes such as manufacturing and welding. Sandblasting thoroughly cleans surfaces and removes unwanted contaminants. It eliminates the need for harsh chemicals. In the oil and gas industry, for instance, abrasive blasting is used to clean machinery, pipelines, and storage tanks. This prevents buildup which can affect both safety and performance.
Applying cosmetic finishing and texturing:
Other than cleaning and preparing surfaces, sandblasting is also used for decorative and cosmetic finishing. Depending on the pressure and abrasive media, you can create different textures, from a matte or satin finish to an anti-slip surface. You will mainly see these unique surface effects in interior design, architecture, and glass etching.
How Does Sandblasting Work?
The abrasive blasting process works by propelling abrasive media against a surface using a sandblaster.
The sandblasting system comprises an air compressor, which generates high-pressure air. The air is then passed to a pressure vessel or blast pot containing the abrasive media. This mixture of abrasive and compressed air passes through a hose and out through a nozzle, directing it onto the target surface.
When the high-velocity abrasive contacts the surface it changes its texture or strips the outer layer depending on the media and technique used.
A proper sandblasting setup is made up of different elements that work together to deliver an efficient blasting process. A basic abrasive blasting system includes the following:
Abrasive media:
This is the material used for blasting and it varies depending on the type of project and result you hope to achieve. Common abrasive media include silica sand, glass beads, steel grit, aluminium oxide, etc.
Air compressor:
It supplies the high-pressure air necessary to blast the abrasive media.
Blast pot or pressure vessel:
It holds the abrasive media and regulates its flow into the air stream.
Blast hose:
This is needed to carry the abrasive-laden air from the blast pot to the nozzle.
Blast nozzle:
It directs the flow of abrasive media onto the surface. Different nozzle types affect coverage, speed, and impact. For instance, straight nozzles provide a concentrated and powerful stream for cleaning while venturi nozzles can offer a wider, more uniform spray for covering larger areas efficiently.
Moisture filter/separator:
Removes moisture from the compressed air before it goes into the blasting pot. This prevents clumping of the abrasive media and ensures consistent flow.
Protective gear:
This includes a respirator or blast hood to prevent inhalation of fine particles, eye protection, gloves, and protective clothing.
Types of Sandblasting Media
The choice of media in sandblasting determines how aggressive the blasting will be and the type of finish you will achieve. Different abrasive blasting media have varying levels of impact and hardness. So some are better suited for heavy-duty stripping while others work better for delicate cleaning.
Here are some common sandblasting media and their uses.
Silica sand:
This is the original sandblasting media–hence the name of the process. It was a popular choice because of its affordability and availability. However, it produces harmful silica dust which has been proven to cause silicosis making it unsafe for workers. Because of this, many countries have strict restrictions on its use.
Steel grit:
This is a powerful abrasive used for cleaning and preparing steel surfaces. It is more aggressive and is suitable for removing heavy-duty rust and paint. It is super durable and can be reused multiple times but it requires specialized sandblasting equipment due to its high impact force.
Glass beads:
These are ideal for achieving a smooth, satin or matte finish. Glass bead blasting can polish, lightly clean, and remove surface contaminants without damaging the underlying material. Glass beads are also reusable, making them a cost-effective and majorly safe alternative to traditional sand.
Aluminum oxide:
This is a highly durable and sharp abrasive that works well for preparing metal surfaces before coating. It is effective for removing tough corrosion and creating a surface that allows for strong adhesion. Despite being more expensive than some other alternatives, it is a preferred choice for many industrial applications, mainly because of its efficiency and longevity.
Garnet:
This is a sharp-edged natural mineral that is effective and environmentally friendly. It is used for industrial cleaning, surface preparation, and waterjet cutting. It is a safer choice than most abrasives because it produces less dust. However, it can be quite expensive.
Plastic media:
This is used for more delicate applications, such as removing paint from car bodies, aircraft parts, and fiberglass surfaces. It is soft and can strip coatings without damaging the underlying materials. It is a popular choice in the automotive and aerospace industries.
Walnut shells and corn cob:
These are biodegradable abrasives mainly used in restoring wood, polishing softer materials, and cleaning delicate metal surfaces. They are gentle but still effective and can remove grime without causing surface damage or warping.
Bicarbonate of soda (baking soda):
This is a mild abrasive ideal for gentle cleaning applications. It removes contaminants from sensitive surfaces without causing etching or damage. Soda blasting is commonly used in automotive restoration, food processing equipment, and fire damage cleanup. It is a deodorizer and can remove the burned smell that remains long after a fire.
Shot Media Properties
The properties of abrasive media have a direct effect on the surface finishing results. Below are the key properties of shot media and how they affect performance in different applications.
Hardness:
Measured on the Mohs Scale (1-10), hardness determines how aggressively the media cuts into the surface. Softer media like walnut shells provide gentle cleaning, while aluminum oxide is more aggressive.
Shape:
Media particles come in different shapes. Round particles create a smoother finish while angular particles cut into surfaces and create a rougher profile.
Density:
Denser and heavier media, like steel abrasives, hit the surface with more force and can remove tough contaminants more efficiently.
Size:
Shot media is available in different mesh sizes which affect the final results. Large mesh profiles are ideal for creating a rougher surface while small mesh profiles offer a smoother finish.
Wrapping Up
Sandblasting is a versatile and effective method of cleaning and preparing surfaces for painting, coating, or other treatments. It is widely used in different industries, including manufacturing, construction, and automotive.
Different abrasive media and blasting techniques create different surface textures, from smooth finishes to rough profiles. Traditional sandblasting with silica sand comes with health risks but modern alternatives like garnet, glass beads, and wet blasting are safer.
Because of its ability to restore and refine surfaces, abrasive blasting remains one of the most reliable methods of achieving the perfect finish.
Frequently Asked Questions About Sandblasting
Q: What Is the Purpose of Sandblasting?
A: Sandblasting is used for surface preparation, cleaning, and finishing. It removes rust, paint, and other unwanted contaminants, leaving behind a smooth or textured surface, depending on the intended results.
Q: Why Is It Called Sand Blasting?
A: Originally, sandblasting involved using sand as the primary abrasive to blast surfaces with high-pressure air. Over time, due to health risks associated with silica sand, the industry adopted safer alternative abrasives, but the term “sandblasting” remained widely used.
Q: What Is Another Name for Sandblasting?
A: Another name for sandblasting, which is more fitting, is abrasive blasting since many different abrasive media (such as glass beads, aluminum oxide, and steel grit) can be used.
Q: Why Is Sandblasting Banned?
A: Traditional sandblasting with silica sand is banned (or strictly regulated) in many places due to the severe health risks of silicosis, a lung disease caused by inhaling fine silica dust.
Q: Is Sandblasting Safe?
A: Sandblasting can be safe when operators take the proper precautions. It is important to wear protective gear, work in ventilated areas, and use approved abrasives. Improper sandblasting, especially with silica-based abrasives, can pose serious health risks.