What is The Difference Between Shot Blasting and Grit Blasting?

The Difference Between Shot Blasting and Grit Blasting?

In simple terms, shot blasting usually uses rounded metallic media to clean or treat a surface, while grit blasting usually uses angular abrasive media to cut into the surface and create a stronger profile for coating adhesion. For industrial steelwork, the main question is not just “which blasting method is best?” but “what surface standard does the coating system need?” If the steel is being prepared for powder coating, hot zinc spray, zinc primer or a protective coating system, the surface must be cleaned and profiled correctly. That is why standards such as SA2.5 blasting and SA3 blasting matter. SA2.5 blasting is very thorough blast cleaning and is commonly used for protective coating preparation. SA3 blasting is a higher standard that cleans the steel to a visually clean metallic finish. At NSP Coatings, we use controlled abrasive blasting because preparation directly affects coating performance

Table of Contents

1. What is abrasive blasting?
2. Why surface preparation matters
3. What is shot blasting?
4. What is grit blasting?
5. Shot blasting versus grit blasting, what is the difference?
6. Why sandblasting is not the right term
7. What are SA2.5 and SA3 blasting standards?
8. Which blasting method should you use?
9. Why NSP uses controlled abrasive blasting
10. FAQs
11. Speak to NSP Coatings

The Difference Between Shot Blasting and Grit Blasting

A coating system is only as good as the surface underneath it. You can use a high-quality primer, a premium powder coating or a specialist protective coating, but if the steel has not been prepared properly, the coating is already at risk before it leaves the factory. Poor preparation can lead to adhesion failure, premature corrosion, rust bleed, flaking paint, costly rework and damaged reputation. That is why understanding the difference between shot blasting and grit blasting matters.

Many people use terms like shot blasting, grit blasting, sandblasting and abrasive blasting as if they all mean exactly the same thing. They do not. The terms are often used loosely, especially when people are asking for prices, comparing quotations or trying to understand what surface preparation they need before coating. This can create confusion and in some cases it can lead to the wrong process being specified.

At NSP Coatings, surface preparation is not treated as an optional extra. It is one of the most important stages in the coating process. Whether the project involves powder coating, hot zinc spray, wet spray coatings, zinc primer or a full long-life protective system, the blasting standard directly affects how well the coating performs.

This article explains the difference between shot blasting and grit blasting, why abrasive choice matters and why correct blasting standards such as SA2.5 blasting and SA3 blasting are so important for industrial steelwork.

What is Abrasive Blasting?

Abrasive blasting is the process of propelling abrasive material at high speed onto a surface to clean, profile or prepare it. In industrial coatings, it is mainly used to remove contaminants and create the correct surface profile for coating adhesion.

Abrasive blasting can remove:

• Rust
• Mill scale
• Old paint
• Dirt
• Contamination
• Oxidation
• Loose coatings
• Surface corrosion

It can also create a mechanical profile on the steel. This profile is important because coatings need something to key into. A surface that looks clean may still be unsuitable if it does not have the correct profile for the coating system being applied.

This is where many coating problems begin. A customer may see a clean piece of steel and assume it is ready for coating. In reality, it may not have been blasted to the right standard, or it may not have been blasted at all.

Why Surface Preparation Matters

Surface preparation is one of the biggest factors in coating performance. If the surface is contaminated, too smooth, poorly blasted or inconsistently prepared, the coating can fail. This is especially important for steelwork exposed to weather, industrial environments, transport handling, moisture or architectural specification requirements.

When steelwork is prepared correctly, the coating has a much better chance of achieving long-term durability. When it is not prepared correctly, even a good coating can fail early.

Common problems caused by poor preparation include:

• Poor coating adhesion
• Rust appearing beneath the coating
• Premature coating breakdown
• Flaking or peeling paint
• Uneven finish
• Reduced corrosion protection
• Failed site inspections
• Expensive rework

For industrial buyers, fabricators, architects and contractors, this is not just a technical issue. It is a commercial one. Failed coatings can mean crane hire, labour costs, site delays, transport costs, removal, re-coating and difficult conversations with customers.

That is why NSP’s wider message is simple: preparation matters. No shortcuts. No hidden compromises.

What is Shot Blasting?

Shot blasting is a type of abrasive blasting where small particles, often steel shot, are fired at the surface at high speed. The process is commonly used to clean steel, remove contaminants and prepare metal surfaces for coating.

The word “shot” usually refers to rounded metallic particles. Because shot is rounder than angular grit, it tends to impact the surface differently. It can clean and peen the surface but may not always create the same sharp angular profile that some coating systems require.

Shot blasting is widely used across industries such as:

• Construction
• Structural steel
• Manufacturing
• Automotive
• Marine
• Engineering
• Agricultural equipment
• Industrial fabrication

In some applications, shot blasting is used to remove rust, scale or paint. In others, it is part of a controlled preparation process before priming, coating or further treatment.

However, the phrase shot blasting is often used as a broad everyday term for blasting. Many customers will ask for shot blasting services even when the process being used is technically grit blasting with angular abrasive. This is why it is important to focus less on the name and more on the required surface standard, abrasive type and final coating system.

What is Grit Blasting?

Grit blasting is also a form of abrasive blasting, but it normally uses angular abrasive particles rather than round shot. These angular particles cut into the surface and create a rougher profile. This makes grit blasting especially useful when preparing steel for protective coatings.

Common blasting media can include:

• Steel grit
• Chilled iron grit
• Aluminium oxide
• Garnet
• Glass media
• Other specialist abrasives depending on the substrate and required finish

Unlike rounded shot, grit has sharper edges. This means it can remove corrosion and old coatings effectively while also creating a more defined surface profile. This profile helps primers, zinc coatings and paint systems bond properly to the surface.

For protective coating work, grit blasting is often the better description when the aim is to prepare steel to a recognised standard such as SA2.5 or SA3.

At NSP Coatings, abrasive blasting is used as a controlled preparation process. The aim is not simply to make the steel look clean. The aim is to prepare the surface correctly for the coating system that follows.

Shot Blasting Versus Grit Blasting, What is the Difference?

The main difference between shot blasting and grit blasting comes down to the abrasive media and the surface profile created.

In simple terms, shot blasting is often associated with cleaning and impact treatment. Grit blasting is more commonly associated with creating a surface profile for coating adhesion.

That said, terminology varies across industries. Some companies use “shot blasting” to describe all types of blasting. Others use “grit blasting” when they want to be more specific about angular abrasive preparation. The safest approach is to define the required preparation standard and coating system rather than relying on a general phrase.

For example, “blast and paint” is not enough information. A proper specification should consider:

• Existing steel condition
• Contamination level
• Rust grade
• Required blasting standard
• Surface profile
• Coating system
• Environment
• Required durability
• Inspection and QA requirements

Why Sandblasting Is Not the Right Term

Many people still use the word “sandblasting” when they mean abrasive blasting. It is a common phrase, but it is not usually the correct term in modern industrial coating work.

The use of sand or other substances containing free silica for blasting articles is prohibited under UK COSHH regulations, as HSE guidance explains. This is because respirable crystalline silica can create serious health risks when inhaled.

So when people say “sandblasting”, they are often using an old-fashioned name for a modern abrasive blasting process. In professional industrial coating work, the correct process normally involves controlled abrasive media, appropriate extraction, PPE, process control and safe working procedures.

This matters because language affects expectations. If a quote simply says “sandblast”, it may not clearly explain what abrasive is being used, what surface standard is being achieved or whether the preparation is suitable for the required coating system.

What Are SA2.5 and SA3 Blasting Standards?

For steel coating projects, blasting standards are critical. The most common standards used in protective coating specifications include SA2.5 and SA3. These relate to the visual cleanliness of the steel after blast cleaning.

According to steel construction guidance, the standard grades under BS EN ISO 8501-1 include Sa 1, Sa 2, Sa 2½ and Sa 3. Sa 2½ is described as very thorough blast cleaning, while Sa 3 is blast cleaning to visually clean steel.

In practical terms:

• SA2.5 blasting is very thorough blast cleaning. It removes mill scale, rust and coatings to a high standard, allowing only limited staining or shadows.
• SA3 blasting is a higher standard where the steel is cleaned to a visually clean metallic finish.

The right standard depends on the coating system and the project requirements.

At NSP Coatings:

• CoreCoat includes SA2.5 blasting as part of a cost-conscious industrial coating option.
• ProLine includes SA2.5 blasting with optional hot zinc spray, transport, QA documentation and a more complete service package.
• Ultra60 uses SA3 blasting, hot zinc spray to specified microns, controlled coating thickness and full QA documentation as part of a premium long-life system.

This is an important point when comparing quotes. A cheaper quote may not include the same blasting standard. It may not include hot zinc spray. It may not include the same level of QA. It may not include the same packaging, transport or documentation.

That is why NSP often says customers are comparing “eggs with apples”. The headline price is only useful if the process behind it is the same.

Which Blasting Method Should You Use?

The right blasting method depends on the substrate, the surface condition and the coating system being applied. There is no single answer that suits every project.

You may need abrasive blasting if the steel has:

• Rust
• Mill scale
• Previous coatings
• Surface contamination
• Poor adhesion risk
• Exposure to weather
• A protective coating specification
• A requirement for zinc primer, hot zinc spray or powder coating

If the project involves structural steel, external metalwork, industrial components, railings, architectural steelwork or fabricated metalwork, the preparation method should be selected carefully.

For example:

• If the aim is general cleaning, a lighter blast may be suitable.
• If the aim is coating adhesion, a controlled profile will be required.
• If the aim is long-term corrosion protection, blasting standard and coating system become even more important.
• If the project involves a high-performance system, SA3 blasting may be required.

A common mistake is assuming that all blasting is the same. It is not. The abrasive, pressure, profile, cleanliness standard and handling after blasting all affect the final coating.

Why NSP Uses Controlled Abrasive Blasting

NSP Coatings uses abrasive grit blasting as part of a controlled coating process. The aim is to prepare steel correctly before applying the right protective system.

This matters because NSP is not simply offering blasting as a standalone cleaning service. Blasting sits within a wider process that can include:

• Grit blasting 
• Hot zinc spray
• Zinc primer
• Powder coating
• Wet spray coatings
• Intumescent paint systems
• A2 standard fire-rated powder coating systems
• QA documentation
• Transport and logistics

Because NSP has dedicated blasting, wet spray, powder coating and QA teams in-house, the process can be managed from preparation through to final inspection. This gives customers better control, clearer accountability and fewer gaps between suppliers.

For fabricators and contractors, this is valuable. Sending steel to one supplier for blasting, another for priming, another for powder coating and another for transport creates more handling, more risk and more room for mistakes. NSP’s in-house process helps reduce that risk.

Why Cheap Blasting Can Become Expensive

Blasting is sometimes treated as a line item to be stripped back to reduce cost. This can be a false economy.

A cheap quote may look attractive, but it may leave out vital parts of the process. For example:

• The steel may not be blasted to the correct standard.
• The surface profile may not suit the coating system.
• Rust or mill scale may remain.
• The coating may not bond properly.
• The job may need reworking later.
• The customer may face delays, site costs and reputation damage.

This links directly to NSP’s Never Sacrifice Performance price promise. If a job comes down to a genuine price difference and the processes being quoted are the same, NSP will review and match like-for-like quotations on CoreCoat and ProLine systems.

The key phrase is “like-for-like”. Same preparation. Same coating process. Same specification. Same finish requirement. Same level of service.

If one quote includes SA2.5 blasting, zinc primer, QA documentation and transport, and another simply says “blast and coat”, they are not the same thing.

FAQs About Shot Blasting and Grit Blasting

Is shot blasting the same as grit blasting?

Not exactly. Both are forms of abrasive blasting, but shot blasting usually refers to rounded shot media, while grit blasting usually refers to angular abrasive media. Grit is often used where a sharper surface profile is needed for coating adhesion.

Is sandblasting still used in the UK?

The term is still used casually, but blasting with sand or substances containing free silica is prohibited for blasting articles under UK COSHH guidance. Modern industrial blasting uses safer and more controlled abrasive media.

Why does blasting matter before powder coating?

Blasting removes contamination and creates the correct surface profile. Without proper preparation, powder coating may not bond correctly, which can lead to early failure, corrosion or peeling.

What does SA2.5 blasting mean?

SA2.5 blasting is a very thorough blast cleaning standard. It is commonly used in industrial coating specifications where steel needs to be cleaned and prepared to a high standard before coating.

What does SA3 blasting mean?

SA3 blasting is a higher blast cleaning standard where the steel is prepared to a visually clean metallic finish. NSP uses SA3 blasting as part of its Ultra60 premium coating system.

Which is better, shot blasting or grit blasting?

It depends on the job. For coating preparation, angular grit is often preferred because it creates a stronger surface profile. For general cleaning or peening, shot may be suitable. The right answer depends on the substrate, coating system and required specification.

Can blasting remove old paint and rust?

Yes. Abrasive blasting can remove old coatings, rust, mill scale and contamination. The level of removal depends on the abrasive, pressure, technique and specified blasting standard.

Why should I use a professional blasting company?

Professional blasting ensures the correct abrasive, profile, cleanliness standard and process control are used. This reduces the risk of coating failure and helps ensure the finished system performs properly.

Speak to NSP Coatings About Shot Blasting and Grit Blasting

The difference between shot blasting and grit blasting is not just technical language. It affects coating adhesion, corrosion protection, long-term durability and the true cost of a project.

At NSP Coatings, we prepare steel properly before coating. Our team can advise on the right blasting standard, the correct coating system and the best route for your project, whether you need SA2.5 blasting, SA3 blasting, hot zinc spray, zinc primer, powder coating, wet spray coatings or a full protective coating system.

With in-house blasting, coating, QA and transport, NSP gives customers a controlled process from start to finish. No shortcuts. No vague specifications. No cutting out preparation to make a quote look cheaper.

To discuss your next project, call NSP Coatings on 01474 363719 or email sales@nspcoatings.co.uk.