Media blasting is a widely used surface preparation technique across industries such as manufacturing, automotive restoration, construction, and aerospace. It involves the use of abrasive materials—known as blasting media—to clean, smooth, or roughen surfaces. One of the most critical factors in achieving the desired results is selecting the appropriate grit size.
Understanding grit size is essential for ensuring efficiency, surface quality, and cost-effectiveness in media blasting projects. In this guide, we’ll break down what grit size is, how it affects the blasting process, and how to choose the right grit size for your specific application.
What is Grit Size in Media Blasting?
Grit size refers to the particle size of the abrasive material used in media blasting. It is typically measured in mesh size, which indicates the number of openings per linear inch in a sieve screen. The higher the mesh number, the smaller the abrasive particles. Conversely, a lower mesh number indicates larger particles.
For example:
- 16-24 mesh: Coarse abrasives, suitable for heavy-duty stripping.
- 50-80 mesh: Medium abrasives, used for general-purpose cleaning and surface prep.
- 120-200 mesh: Fine abrasives, ideal for polishing and delicate applications.
Different materials—such as aluminum oxide, glass beads, or garnet—come in various grit sizes, each designed for specific applications.
How Grit Size Affects the Blasting Process
1. Surface Finish and Texture
The size of the grit determines the roughness of the finished surface.
- Coarse grits (lower mesh numbers) create a rougher texture, ideal for applications requiring strong adhesion, such as coating and painting preparation.
- Fine grits (higher mesh numbers) result in smoother surfaces, often used in polishing and finishing applications.
2. Material Removal Rate
- Larger grit particles remove material faster but can also cause more surface damage.
- Smaller grit particles remove contaminants more gently, making them better for delicate materials like aluminum, stainless steel, and fiberglass.
3. Efficiency and Media Consumption
- Fine grit sizes tend to break down faster, meaning they may need to be replaced more frequently.
- Coarse grit sizes are more durable but may require higher pressure to achieve the same level of cleaning as finer abrasives.
Selecting the right grit size helps balance efficiency, cost, and surface quality in your blasting operation.
Common Grit Sizes and Their Applications
| Grit Size | Common Media Types | Best Used For |
| 16-24 | Steel Grit, Aluminum Oxide | Heavy rust, thick paint removal, industrial surface prep |
| 30-40 | Garnet, Crushed Glass | Coating removal, aggressive cleaning, general surface prep |
| 50-80 | Glass Beads, Plastic Media | Automotive parts, light rust removal, cleaning delicate metals |
| 100-200 | Walnut Shells, Soda Blasting | Soft metals, historical restoration, fine surface cleaning |
Each type of blasting media is available in various grit sizes, making it crucial to choose the right combination based on the material, surface condition, and desired finish.
Choosing the Right Grit Size for Your Application
1. Consider the Material Being Blasted
- Steel and Iron: Can withstand coarser grit (16-40 mesh) for heavy-duty cleaning.
- Aluminum and Stainless Steel: Require finer grit (50-120 mesh) to avoid pitting or excessive roughness.
- Wood and Soft Metals: Best cleaned with fine or non-abrasive media like walnut shells or soda (100+ mesh).
2. Determine the Level of Surface Preparation Needed
- For deep cleaning and rust removal: Coarse abrasives like steel grit (16-30 mesh) are ideal.
- For preparing surfaces for painting or coating: Medium abrasives like garnet (30-80 mesh) create the right texture for adhesion.
- For polishing or finishing work: Fine abrasives (100+ mesh) ensure a smooth, refined surface.
3. Assess Efficiency and Cost Factors
- Coarse abrasives work faster but may be more aggressive, requiring additional refinishing.
- Fine abrasives last longer but may require higher pressure or more time to achieve results.
By selecting the right grit size, businesses can improve efficiency, reduce media waste, and enhance surface quality.
Grit Size in Different Blasting Methods
Different blasting techniques require specific grit sizes for optimal performance.
1. Dry Ice Blasting
- Does not use traditional abrasive grit, but rather solid CO₂ pellets that sublimate upon impact.
- Ideal for delicate surfaces, electrical components, and food processing equipment.
2. Laser Cleaning
- No abrasive grit is used; instead, laser pulses remove contaminants without altering the surface texture.
- Used for precision applications like automotive restoration and aerospace cleaning.
3. Media Blasting
- Uses grit-based materials to physically remove coatings, rust, and debris.
- Requires careful grit size selection based on the material and desired finish.
The Importance of Grit Size in Coating and Painting Applications
One of the most important uses of media blasting is preparing surfaces for painting, powder coating, or other protective finishes. The right grit size ensures proper adhesion and durability.
- Too coarse of a grit may create an overly rough surface, leading to excessive paint absorption.
- Too fine of a grit may leave the surface too smooth, reducing adhesion strength.
Industry standards, such as SSPC (Society for Protective Coatings) and NACE (National Association of Corrosion Engineers), provide guidelines for grit size selection to achieve the correct surface profile.
Common Mistakes When Selecting Grit Size
1. Using Grit That’s Too Aggressive
- Can damage delicate materials like aluminum or thin metals.
- May leave an excessively rough surface that requires further refinishing.
2. Choosing Grit That’s Too Fine for the Job
- Slows down the blasting process, increasing labor costs.
- May not effectively remove stubborn contaminants like thick rust or heavy coatings.
3. Ignoring Equipment Compatibility
- Not all blasting equipment can handle ultra-fine or ultra-coarse grit sizes.
- Ensure proper nozzle size and air pressure settings for optimal performance.
Avoiding these mistakes ensures better results, lower costs, and extended equipment lifespan.
Final Thoughts on Grit Size Selection
Grit size plays a crucial role in the effectiveness, efficiency, and safety of media blasting. Whether you’re removing rust from industrial equipment, preparing a surface for painting, or restoring delicate materials, selecting the right grit size is key to achieving the best results.
By understanding how grit size affects surface texture, material removal, and overall cost-efficiency, businesses can make informed decisions and improve the success of their media blasting operations.
For expert advice and professional media blasting services, contact Interstate Blasting today. Our team can help you choose the best grit size and media for your specific project needs.
