Comprehensive Guide to ABRASIVE Blast CLEANING
Discover everything to know about blast cleaning in our comprehensive guide. Learn what abrasive blasting is, how it works, types of blast material & more.
Guide to Blast Cleaning: What Is It, How It Works & More
When exposed to harsh environments, industrial surfaces may have mill scale and can accumulate rust, compromising the integrity and performance of various substrates. Applying coatings to protect steel, concrete and other materials won’t help slow corrosion if it is applied before achieving the proper anchor profile for the coatings to adhere. Could blast cleaning, also known as abrasive blasting, be a suitable solution to this problem?
Traditional cleaning methods fail to fully remove contaminants, resulting in costly repairs, increased downtime, and reduced operational efficiency. Incomplete surface preparation also affects the adhesion of protective coatings, leaving the surface vulnerable to further damage.
Blast cleaning offers a comprehensive solution for removing surface contaminants, ensuring optimal surface preparation and extending the lifespan of industrial coatings. This guide covers everything you need to know about blast cleaning, from methods and materials, to finding professional blasting services and more.
Key Takeaways
- Blast cleaning effectively removes a wide range of contaminants, ensuring clean and prepared surfaces for various industrial applications.
- There are multiple abrasive blast cleaning methods available, each suited to specific needs and materials.
- Selecting the right abrasive material is crucial for achieving the desired anchor profile and can minimize safety risks.
- Achieving the right anchor profile optimizes the performance of the coating by allowing it to maximize how well it adheres to the surface material and providing a protective barrier from corrosion.
- Choosing the right service provider is key to ensuring quality, efficiency, and compliance with industry standards.
Understanding Blast Cleaning: What is Abrasive Blasting and How Does It Work?
Blast cleaning pressurizes abrasive material into a high-velocity flow to remove debris from durable surfaces, like a fire hose, but with various types of material much harder than water. This process of cleaning is an efficient way to remove visible debris like rust, paint, mill scale, and other stubborn residue on surfaces where small section sanding is impractical or ineffective.
Using an air compressor or centrifugal impellers, small pieces of various materials called media are collectively blasted at a high rate of speed onto the surface. When the blast media hits the surface, it breaks up any loose debris, causing it to disintegrate into the media and fall away from the surface. Blasting can reach surfaces inaccessible to sandpaper, wire brushes, or other tools, making it ideal for thorough cleaning of intricate surfaces, like mechanical assemblies and parts.
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Why is Abrasive Blasting Important to the Industrial Painting Process?
Painting over dirty surfaces compromises the integrity of the protective coating, no matter how high quality the product is. Just like painting over old paint, placing any sealant or coating over dirt and debris will create space between the surface and the overlay. Where coating does not properly adhere to the surface, the product will be ineffective and eventually chip off and fall away. When you hire professional painters to complete a job, you expect high-value work with a lasting finish. A professional can achieve this level of quality by thoroughly preparing the surface before coating the application with abrasive blast cleaning.
Blast Cleaning Methods, Technologies & Equipment
There are as many techniques of abrasive blast cleaning as there are levels of corrosion, types of paint and surface materials. The media and methods of blast cleaning used to achieve the proper surface anchor profile are determined by several factors including surrounding environment, amount of corrosion/mill scale, and underlying surface structure. Thorough surface cleaning is crucial to providing an optimal anchor profile for coatings applications.
Equipment Essentials for Abrasive Blasting
As the leading experts in industrial painting, Conomos maintains many systems to tackle a variety of abrasive blast cleaning methods for surface preparation.
Blasting Systems:
- Pneumatic systems use compressed air to propel abrasive media like steel grit, used in heavy-duty cleaning and delicate tasks across various substrates.
- Mechanical wheel systems, or centrifugal blasters, employ high-speed rotating wheels to throw abrasives onto surfaces for large-scale, continuous operations such as removing rust or scale from metal in manufacturing environments.
- Robotic blasting systems use programmable robotic arms to deliver consistent, high-quality surface preparation for complex geometries and high-precision applications. Robotic systems offer advanced control, safety, and adaptability.
- Innovations in abrasive blast cleaning incorporate unlikely material identified as the most effective and environmentally safe, such as garnet.
Dust Collection and Media Reclaim Systems:
- Dust collectors come in various forms like baghouse or cyclone collectors, each suited to different levels of dust production and types of abrasive media. Designed to capture and filter out fine particles and contaminants generated during blasting, these vacuum-like tools ensure a clean and safe work environment for operators while preventing airborne pollution.
- Media reclaim systems are crucial for cost-effective blasting, as they collect, clean, and recycle spent abrasive media, separating reusable material from dust and debris. These systems can be pneumatic or mechanical, and they help reduce media consumption and disposal costs while maintaining consistent blasting performance.
- Integrated systems combine dust collection, media reclaim, and blasting equipment into a cohesive setup that streamlines the entire blasting process. These systems are ideal for larger, high-volume operations, offering seamless performance, reduced downtime, and enhanced control over blasting parameters. Integrated systems improve efficiency, safety, and sustainability in industrial surface preparation.
Safety Features and Operator Protection:
- Personal protective equipment, or PPE, includes blast suits, gloves, helmets with built-in air filtration, and respiratory protection to prevent inhalation of harmful particles.
- Automated protocols enhance operator safety by incorporating technology to monitor and control blasting parameters, emergency shutdowns, and remote operations. Automation in these areas reduces the risk of human error and exposure to hazardous environments.
- Environmental controls manage and mitigate the impact of blasting activities on both the immediate area and on a larger scale of sustainability. Such controls include dust suppression systems, containment barriers, and proper disposal or recycling of blasting media and waste materials.
Containment Solutions:
- Blast rooms are large, enclosed spaces designed for heavy-duty surface preparation of sizable components, such as structural steel, piping or machinery parts.
- Blast cabinets are smaller, self-contained units ideal for precision blasting of smaller parts or components. They allow operators to manipulate items through glove ports while viewing the process through a secure window, offering a clean and efficient solution for tasks like rust removal or surface finishing.
- Portable enclosures are like mobile blast rooms. The enclosures provide flexibility for on-site blasting projects. Perfect for situations where the workpiece is immobile or too large for a blast room.
Blast Media Delivery
1. Dry Blasting:
- Sand is one abrasive medium that is no longer typically used due to environmental and worker protection concerns. It is ideal for removing rust, paint and scale from surfaces, but can generate significant amounts of dust contributing to health risks.
- Grit blasting employs harder, angular materials like steel grit, which is effective for heavy-duty cleaning and surface preparation. Hard grit creates an anchor profile on the treated surface to aid in the adhesion of protective coatings.
- Steel shot blasting uses spherical steel shots to clean and strengthen metal surfaces, creating a layer of compressive stress on the surface of the material, which strengthens it against cracking and fatigue.
2. Wet Blasting:
- Ultra High-pressure water blasting removes contaminants without abrasive materials, making it ideal for environments where dust suppression is critical. Effective for cleaning concrete, ship hulls and other large surfaces.
- Sponge blasting uses sponge media to create a dust-free blasting method that’s less aggressive, making it suitable for delicate surfaces or environments where dust control is necessary. It is good for surfaces where the sponge can absorb contaminants.
- Slurry blasting mixes water with abrasives to reduce dust and provides a more controlled, less aggressive blast. Use slurry blasting where minimal surface impact is required.
3. Specialized Methods:
- Dry ice blasting uses pellets which evaporate on contact with the surface, leaving no residue and making it ideal for cleaning sensitive equipment in industries like food processing and electronics.
- Soda, or sodium bicarbonate, blasting is perfect for delicate surfaces such as engine parts, glass, or soft metals, as it minimizes damage while effectively removing contaminants.
- Walnut shell blasting is a gentler blasting method using crushed shells, suitable for cleaning softer surfaces like aluminum without damaging the underlying material.
Abrasive Materials Used in Blast Cleaning
Materials for abrasive blast cleaning range in size, shape, and hardness to provide a variety of options for the proper preparation of any surface.
1. Garnet
A naturally occurring mineral with a sub-angular shape and hardness of 6.5–7.5, garnet provides a balance between cutting speed and surface smoothness. It is suitable for medium to high-pressure dry or wet blasting.
2. Sand
A naturally occurring abrasive with a sharp, angular shape and a Mohs hardness of 6-7, sand is traditionally used for removing rust, paint, and scale from steel and concrete surfaces. It is suitable for high-pressure, dry blasting; however, because of health concerns of silica dust exposure, safer alternatives are used.
3. Steel Grit
Angular and a Mohs hardness rating of 6-7, steel grit is available in various sizes and is ideal for aggressive blasting to remove rust, mill scale, and coatings. Best delivered using high-pressure air or wheel blasting systems
4. Glass Beads
Round and smooth, with a Mohs hardness of 5.5-6, glass beads are excellent for peening and finishing surfaces without removing the base material. They are best used in low-pressure blasting for non-aggressive cleaning.
5. Crushed Glass
Angular and relatively soft Mohs hardness 5.5-6, crushed glass is ideal for general-purpose cleaning and paint removal. It is best used in medium pressure blasting with minimal surface damage.
6. Coal Slag
Coal slag has a Mohs hardness rating of 6-7 and is efficient at cutting through thick surface coatings such as rust and paint. It is angular in shape with sharp edged particles that come in a variety of sizes.
7. Copper Slag
Copper slag has a Mohs hardness rating of 6-7. The use of copper slag is ideal for detail work (such as on an intricate bridge) as this media produces sharp, clean edges when blasting and creates minimal dust. Copper slag is able to be used repeatedly which also makes it environmentally friendly.
8. Aluminum Oxide
Sharp and angular with a high hardness of 9, aluminum oxide is effective for fast-cutting and heavy-duty surface preparation, including paint and rust removal. Suitable for dry or wet blasting at medium to high pressures.
9. Plastic Media
Available in various shapes and sizes, with a lower hardness of 2-3, plastic media is gentle and ideal for delicate surfaces, like aluminum or composites. It works well in low-pressure, dry blasting environments.
10. Walnut Shells
Biodegradable and angular, walnut shells have a Mohs hardness of 3-4 and are perfect for removing paint and coatings without damaging the underlying surface. They are best used in low-pressure, dry blasting systems.
11. Baking Soda (Sodium Bicarbonate)
Soft and angular with a Mohs hardness of 2.5, baking soda is excellent for cleaning delicate surfaces or removing grease and oil. Ideal for low-pressure dry or wet blasting, especially in dust-free environments.
12. Steel Shot
Round and hard (Mohs hardness of 7), steel shot is used for peening and creating a polished finish on metal surfaces. It is most effective when delivered using wheel blasting systems.
13. Corn Cob
Soft and angular, with a low hardness of 4-4.5, corn cob is ideal for cleaning wood, brick, or delicate surfaces without etching. Best used in low-pressure, dry blasting settings.
How to Choose the Right Abrasive Material
Your industrial paint professional takes many factors into consideration when preparing surfaces for a coating application. The most important factor is the type of surface being prepped and the nature of the contaminants needing to be removed. These details inform the technology, method of delivery, and the type of media required to prep the surface adequately for coatings.
Abrasive Blast Media Chart
| Industrial Surface | Common Contaminants | Abrasive Blasting Technology | Method | Media Type | Media Hardness (Mohs Scale) | Notes |
| Steel | Rust, mill scale, oil | Dry blasting, wet blasting | Pressure blasting | Garnet, steel grit, coal slag, copper slag | Garnet: 6.5–7.5, Steel Grit: 6-7 Coal Slag: 6-7 Copper Slag: 6-7 |
Dry for rust/mill scale, wet for oil removal |
| Concrete | Mold, mildew, old paint | Dustless blasting, shot blasting | Low-pressure wet blasting | Crushed glass, steel shot | Crushed Glass: 5.5-6, Steel Shot: 7 | Avoid over-aggressive media to prevent damage |
| Aluminum | Oxidation, grease | Wet abrasive blasting | Low-pressure water jetting | Glass beads, plastic media | Glass Beads: 5.5-6, Plastic Media: 2-3 | Non-ferrous media to avoid surface damage |
| Galvanized Metal | White rust, oil residue | Vapor blasting | Medium pressure | Aluminum oxide, glass beads | Aluminum Oxide: 9, Glass Beads: 5.5-6 | Low abrasion to prevent removing zinc coating |
| Stainless Steel | Scale, tarnish, oil | Wet blasting | Low to medium pressure | Glass beads, aluminum oxide | Glass Beads: 5.5-6, Aluminum Oxide: 9 | Low aggression to maintain surface finish |
| Iron | Rust, mill scale | Dry blasting | High-pressure air blasting | Steel grit, aluminum oxide | Steel Grit: 6-7, Aluminum Oxide: 9 | High abrasion to remove heavy rust and scale |
| Copper | Oxidation, patina | Wet abrasive blasting | Low-pressure wet blasting | Walnut shells, plastic media | Walnut Shells: 3-4, Plastic Media: 2-3 | Non-abrasive to avoid damaging surface |
| Fiberglass | Old paint, marine growth | Soft abrasive blasting | Low-pressure dry or wet | Baking soda, plastic media | Baking Soda: 2.5, Plastic Media: 2-3 | Gentle cleaning to avoid damage to surface |
| Wood | Old paint, mold | Soft abrasive blasting | Low to medium pressure | Crushed glass, walnut shells | Crushed Glass: 5.5-6, Walnut Shells: 3-4 | Use gentle media to prevent wood grain damage |
Abrasive Blasting Industry Standard & Compliance
Conomos takes pride in their industry compliance designations. Because of the inherent safety concerns of abrasive blast cleaning, there are multiple regulatory agencies dedicated to ensuring standards of quality, safety, and sustainability of this practice.
Surface Preparation Standards
AMPP, the Association for Materials, Protection and Performance was formed by combining two industry standards organizations: The Society for Protective Coatings (SSPC) and the National Association of Corrosion Engineers (NACE). AMPP and the International Organization for Standardization (ISO) define surface preparation standards to ensure substrates are adequately cleaned for coating applications. AMPP standards, primarily used in North America, define cleanliness with specific criteria for rust, mill scale, and old coatings removal. ISO standards, used globally, provide equivalent cleanliness grades. Each organization outlines specific inspection criteria, including visual assessments, surface profile measurements, and contamination checks, using tools like replica tape and comparators to ensure consistency and adherence.
The key differences among these entities lie in regional usage, terminology, and the depth of inspection requirements. While AMPP provides detailed guidance on inspector certifications and specific inspection techniques, ISO offers broader, internationally recognized criteria. Despite these differences, the standards are often cross-referenced to facilitate global consistency, with a common goal of achieving optimal surface cleanliness and profile for effective coating adhesion and long-term performance.
Health and Safety Regulations
Occupational Safety and Health Administration (OSHA) regulations focus on protecting workers from hazards, such as inhalation of dust and toxic substances, exposure to high noise levels, and physical injuries. OSHA standards mandate the use of appropriate PPE. Employers must also implement engineering and administrative controls to ensure the safety of their employees. Mandated safe operation procedures, such as ensuring equipment is properly maintained and inspected, also prevent accidents and ensure worker safety.
The National Fire Protection Association (NFPA) provides guidelines on dust control and fire prevention to minimize the risks in abrasive blasting operations. These guidelines ensure proper ventilation, regular cleaning, and the use of fire suppression systems. NFPA standards require grounding and bonding of equipment and the use of non-sparking tools to prevent static discharge, which can ignite dust. Emergency protocols and personnel training further manage fire risks effectively.
Environmental regulations for abrasive blasting operations, governed by entities like the Environmental Protection Agency (EPA) and local regulatory bodies, focus on minimizing the environmental impact of blasting waste and emissions. Best practices for waste management include using recyclable blasting media, containing and properly disposing of spent media and hazardous materials, and employing dust suppression techniques to reduce air pollution. Facilities must comply with regulations regarding the handling, storage, and disposal of waste to prevent soil and water contamination.
Abrasive Blast Cleaning FAQs
What is the difference between sandblasting and abrasive blasting?
Sandblasting is often used as a general term, but it originally referred to using sand as the abrasive media. Due to health hazards associated with silica dust, sand is no longer used. Today, abrasive blasting is the more accurate term and includes a range of safer media like steel grit, glass beads, and garnet, each chosen for specific cleaning needs and surface finishes.
What materials can be cleaned using abrasive blast cleaning?
Abrasive blast cleaning can clean materials such as steel, concrete, aluminum, stainless steel, fiberglass, wood, and copper, removing rust, paint, mill scale, and other surface contaminants.
Is abrasive blasting environmentally friendly?
Abrasive blasting can be environmentally friendly if it uses recyclable media, proper dust collection systems, and containment measures to manage waste and reduce air pollution. Adherence to regulations and best practices minimizes environmental impact.
What is commercial blast cleaning?
Commercial blast cleaning is a surface preparation standard where visible contaminants like rust, mill scale, and old coatings are removed, except for slight stains, to achieve a uniform, clean surface suitable for coating.
What If I Need Professional Blast Cleaning Services?
Professional blast cleaning services are essential to the surface preparation and high performance Conomos provides in their industrial coating services and are not completed as a stand-alone service. We adhere to industry compliance standards to ensure high-quality results, using abrasive blasting solutions when necessary for optimal coating adhesion and performance.
When you contact Conomos for your next tank lining, fireproofing, industrial painting, or protective coating project, we will take all the necessary steps to ensure your surfaces are prepared to the highest standards for maximum coating longevity. If you think your coating job requires abrasive blast cleaning, contact one of our experts who will give you an honest assessment and point you in the right direction for the best possible solution. Conomos recognizes each project is unique and relies on its more than 125 years’ experience when partnering with their customers to determine how to proceed.
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