Sandblasting Alloy Wheels: A Refurbishing Guide

Sandblasting alloy wheels is a process that can be used to remove factory paint or primer, corrosion or grime, or to get down to the plain metal surface to polish the wheels. There are different methods of sandblasting, including dry blasting and wet blasting, and different media that can be used, such as glass beads, sodium bicarbonate, or walnut shells. It is important to choose the right media and blasting method to avoid damaging the alloy wheels. Sandblasting alloy wheels can be done by professionals or as a DIY project, but it is important to take the necessary precautions to ensure the integrity of the wheels is not compromised.

Sandblasting aluminium wheels vs other surfaces

Sandblasting aluminium wheels is a process that can be used to remove paint, corrosion, grime, or clear coats from the wheel's surface. Aluminium is not as commonly sandblasted as other surfaces, like steel, but it can be necessary at times. When sandblasting aluminium, it is crucial to consider the choice of blast media, sandblast pressure, and the completion of a small spot test.

Choosing the Right Blast Media

The choice of blast media is critical when sandblasting aluminium. Steel-based media, such as steel shot or steel grit, should be avoided as they can impregnate the aluminium surface and lead to corrosion. Suitable blast media options include glass beads, sodium bicarbonate (baking soda), walnut shells, aluminium oxide, and crushed glass. Glass beads or soda are ideal if the goal is to achieve a polished look, while aluminium oxide or crushed glass are better for creating an anchor profile for repainting.

Sandblasting Pressure for Aluminium Surfaces

Aluminium panels are often thinner than those made of other materials, making them susceptible to warping during the sandblasting process. To prevent warping or creating indentations, it is recommended to start with a low pressure of 50 to 60 PSI and gradually increase as needed. Testing a small section of the surface first can help determine the appropriate pressure and ensure the desired results.

Sandblasting Aluminium Wheels vs. Other Surfaces

Sandblasting aluminium wheels differs from sandblasting other surfaces primarily due to the unique characteristics of aluminium. Aluminium is softer than other metals, and its panels are often thinner, requiring adjustments in the sandblasting process to avoid damage. While sandblasting aluminium wheels may be effective in improving their appearance, it is crucial to consider the potential risks and take the necessary precautions.

In comparison, sandblasting other surfaces, such as steel or iron, may not require the same level of caution regarding media choice and pressure settings. However, each material has its own unique properties that need to be considered when determining the appropriate sandblasting technique. For example, steel surfaces may require more aggressive media and higher pressures to achieve the desired results.

Additionally, the size of the object being sandblasted can also influence the choice of equipment. For larger surfaces, such as automobile exteriors or boat hulls, an outdoor pressure pot sandblaster may be the best option. On the other hand, smaller objects like aluminium wheels, rims, or parts may benefit from using a vapor blast cabinet or a slurry blasting cabinet, which reduces blasting time and eliminates the need for a separate polishing step.

Choosing the right blast media

Media Type

The type of media you choose will depend on the specific task at hand. For removing paint, corrosion, or contaminants from alloy wheels, glass beads, crushed glass, or aluminium oxide are effective options. These media types are also suitable for creating an anchor profile for re-powder coating or re-painting. If your goal is to achieve a smooth polished surface finish, glass beads or soda are recommended. For a less aggressive approach, walnut shells or soda can be used.

Media Size

The size of the media particles also plays a role in the blasting process. For example, using a finer grade of media, such as 80 or 100 mesh glass beads, can create a smoother finish. On the other hand, a coarser grade, like 40/70 mesh crushed glass, may be chosen for more aggressive stripping.

Media Compatibility with Alloy

It is crucial to select a media type that is compatible with the alloy material. Some media, like aluminium oxide, can be too aggressive for aluminium wheels and may alter the texture or cause dimpling. Plastic media is recommended for alloy wheels as it is less likely to damage the relatively soft cast aluminium.

Media Compatibility with Equipment

Consider the type of blasting equipment you are using and choose a media type that is compatible. For example, a wet blast cabinet, which is commonly used for alloy wheels, typically uses media mixed with water. Glass beads, crushed glass, or aluminium oxide are suitable options for this process.

Environmental Considerations

If you are concerned about dust or mess, a wet blasting process using a slurry blast cabinet can eliminate dust and reduce the amount of airborne media. This method also reduces prep time compared to dry blasting. However, keep in mind that wet blasting requires a quicker coating process to prevent oxidation.

Safety

Always prioritise safety when choosing blast media. Avoid using media that is harder than the alloy, such as steel shot or steel grit, as it can create a surface profile that leads to corrosion. Additionally, ensure you have the appropriate safety equipment, such as a respirator, to protect yourself from any harmful particles or chemicals during the blasting process.

Sandblasting pressure for aluminium surfaces

Sandblasting aluminium alloy wheels can be a great way to remove factory paint, primer, corrosion, or grime. It can also be a precursor to repainting or powder coating the wheels. However, it is important to select the right sandblasting pressure to avoid damaging the thinner panels of aluminium alloy wheels.

The recommended sandblasting pressure for aluminium alloy wheels is generally within the range of 40-80 psi (2.8-5.5 bar). This range effectively removes paint, primer, corrosion, or grime without causing excessive surface damage. Starting at a lower pressure, around 50-60 PSI, and gradually increasing is advisable to avoid warping and creating indentations.

For contained blasting, such as in an abrasive blast cabinet, the size of the cabinet and blast nozzle will affect the required PSI. Larger nozzles require more air pressure to achieve effective blasting.

Before blasting the entire surface, it is essential to test a small section to ensure the chosen pressure and blasting media achieve the desired results without causing any damage.

Additionally, the choice of blasting media is crucial when sandblasting aluminium. Glass beads, sodium bicarbonate, or walnut shells are commonly used for blasting aluminium surfaces. Steel shot or grit should be avoided as they can create corrosion.

The pros and cons of wet and dry blasting

Sandblasting alloy wheels is a popular method of removing dirt, grease, corrosion, grime, paint, and powder coating. There are two main methods of sandblasting: wet and dry blasting.

Wet Blasting

Wet blasting, also known as vapor blasting, uses a mixture of water and abrasives to clean alloy wheels. This method has grown in popularity due to its ability to reduce dust and provide a cleaner surface. It is also beneficial for surfaces that require a thorough wash with water. The addition of water to the media stream can also help reduce the amount of media used. Furthermore, wet blasting is less sensitive to outside conditions and eliminates the need for a separate polishing step.

However, one of the biggest disadvantages of wet blasting is the higher initial cost, as it requires both a sandblast pot and a water injection system. It can also result in flash rusting, leaving less time to apply a protective coating. Containment of blast media can be challenging, and users may not be able to stop blasting for extended periods without causing issues. Additionally, wet-blasted surfaces must be dried properly to prevent rusting, and the blasted surface must be coated quickly to prevent oxidation.

Dry Blasting

The traditional method for blasting aluminum surfaces is dry blasting, followed by polishing and painting or coating. Dry blasting is suitable for larger surfaces like automobiles or boat hulls and is typically done outdoors with a pressure pot sandblaster.

One advantage of dry blasting is that it does not require the same level of drying and coating speed as wet blasting to prevent rusting or oxidation. However, dry blasting generates a significant amount of dust, which can be challenging to dispose of.

Both wet and dry blasting have their pros and cons, and the choice between the two depends on the specific requirements and constraints of the project. Wet blasting is advantageous for its dust reduction, cleaning capabilities, and reduced media use, but it is more expensive and requires prompt drying and coating to prevent rusting. On the other hand, dry blasting is a more traditional method suitable for larger surfaces but produces more dust and requires an additional polishing step.

How to avoid structural damage

Sandblasting alloy wheels is a great way to strip away old paint, powder coating, rust, or grease. However, if not done properly, it can cause structural damage to the wheels. Here are some tips to avoid structural damage when sandblasting alloy wheels:

Choose the Right Blast Media:

Avoid using steel shot or steel grit as they are harder than aluminum and can create a surface profile that leads to corrosion. Instead, opt for glass beads, sodium bicarbonate (baking soda), walnut shells, or crushed glass. These media are effective in removing coatings without causing harm to the surface.

Control the Sandblasting Pressure:

Alloy wheels often have thinner panels, making them susceptible to warping during blasting. To prevent this, start with a low pressure of around 50-60 PSI and gradually increase as needed. This will help avoid warping or creating significant indentations on the wheel's surface.

Test on a Small Area First:

Before blasting the entire wheel, test a small section to ensure the chosen media and pressure settings are suitable. This will allow you to adjust your technique and avoid potential structural damage.

Use a Wet Blasting Technique:

Consider using a wet blast cabinet, which combines direct pressure blasting with water to eliminate dust and reduce the risk of embedded media particles. This method is more efficient and effective than traditional dry blasting and polishing methods.

Protect the Wheel Surface:

If there are machined or delicate areas on the wheel, use duct tape or other protective coverings to shield them from direct blasting. This will help prevent any unintended damage to those areas.

By following these guidelines and consulting with professionals, you can effectively sandblast alloy wheels while minimizing the risk of structural damage.

Frequently asked questions