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Innovations in Shot Blasting & Painting Techniques

If you want to maintain the structural integrity and enhance the longevity of metal work, it’s essential that you protect it as much as possible against abrasion and corrosion. However, before you get to work and apply any protective coatings such as paint, you should ensure the surface of the metal is prepared thoroughly through steel shot blasting.

Not sure what this entails? Take a closer look at this technique and discover what it does and how it works.

What is shot blasting?

If you’re wondering, “What is shot blasting steel,” you’re about to find out. This process is an essential part of preparing materials for use or for additional manufacturing processes. Used in almost every industry that requires the use of metals or other hard materials, the process sees metal shot applied to the relevant substance to help improve its qualities, toughness, and aesthetics.

Steel shot blasting strips away elements you do not need or want on your chosen material. While the process itself is simple, performing it successfully is complex enough to require a skilled team that knows how to achieve maximum effectiveness, minimise wastage, and understands the risks involved.

How does shot blasting work?

The shot blasting process involves the deployment of a high-quality abrasive at high force against the material. For example, if you are thinking about painting galvanized steel, you should first prepare it by shot blasting.

The tiny abrasive elements are directed at the metal abrade (strip) the metal’s top layer. This removes rust, cosmetic damage, dirt, and imperfections, prepping the metal for follow-on treatments or for use. If the metal was painted previously, steel shot blasting will remove the old paint. You can increase the efficiency and productivity of peening, cutting, and other surface preparations by increasing the hardness of the abrasive.

Modern shot blasting systems are comprised of six key components. These are:

  • Shot Delivery System: This system, which uses either compressed air or an enclosed centrifuge, controls how the shot is applied to the metal.
  • Material Recovery System: This system allows for constant cleaning by capturing fallen shot, returning it to the blasting equipment, and filtering it internally to remove contaminants before it is reused.
  • Air Filtration System: This system usually uses baffles, replaceable cartridges, or both to act as a dust collector that prevents contaminants and particle fragments from entering the air in the workspace.
  • Blasting Area: The actual steel shot blasting takes place in the blasting area, which usually is known as a blast cabinet. The cabinet is made from hardened materials that cannot be penetrated by high velocity shot. Blasting areas can be sealed to prevent contaminants from entering the workspace and to reduce air pressure.
  • Transport System: The transport system is used to ensure the material being blasted is correctly and safely secured, preventing it from being damaged and protecting the operator from the risk of injury.
  • Control Unit: The operator uses the control unit to start, stop, and manage the shot blasting process.

Shot blasting techniques

There’s more than one shot blasting technique that you can use to prepare for painting galvanized steel or for using industrial steel paint. Let’s take a quick overview of them.

  • Micro-abrasive blasting: This dry technique uses a small nozzle to direct a fine stream of abrasive material at a specific area.
  • Bead blasting: This technique uses glass beads to remove surface deposits such as paint, calcium, and fungus.
  • Wheel blasting: In this airless technique, centrifugal force is used to shoot abrasive material against a surface – no propellants are involved.
  • Hydro/water blasting: In this technique, a high-pressure water jet is used to remove chemicals, debris build-up, or paint.
  • Wet abrasive blasting: This steel shot blasting technique uses cold or hot water to remove dust, grease, and hazardous materials. Detergent may be added to the water.
  • Dry ice blasting: This technique uses dry ice and air to decontaminate surfaces while removing debris from them.
  • Bristle blasting: In this technique, a high-carbon rotary steel brush is used to prepare the metal’s surface.
  • Vacuum blasting: This technique uses dry blasting methods, and it collects blast media during the process, minimising dust and spills.

Painting industrial steel

While painting steel isn’t absolutely necessary after shot blasting, the paint stops the metal from rusting, and it provides a cleaner finish. If you do not paint steel after shot blasting, the metal can begin to rust again soon after the process.

Shot blasting is an essential if you want to coat steel products with industrial steel paint effectively. The scratching and etching of the metal surface that occurs during the shot blasting process makes it easier for the paint to bond and stick to the metal, reducing the possibility of the paint chipping easily.

When preparing steel items for painting, we shot blast them to SA2.5, which refers to the degree of the metal’s cleanliness after the blasting process. After blasting, we paint the item in one continuous spray before drying the item on a rack prior to cutting it.

Is painting galvanized steel possible?

Painting galvanized steel is not advisable. Firstly, there’s no need to paint galvanized steel, as the layer of zinc on the metal created by the galvanization process protects the metal from corrosion. Secondly, the zinc layer rejects paint. Regardless of the number of layers of paint you apply to galvanized steel, the zinc layer will cause the paint to peel and shed.

How is steel painted?

After steel products have been through the shot blasting process, we put them in a painting machine with a double-headed painter. One head is positioned above the steel, while the other is positioned below it. As the steel passes through the machine, the paint is evenly distributed on both sides in one continuous spray.

Once the products have been thoroughly coated in industrial steel paint, they are dried on racks. When dry, the products on the racks are sorted according to the machines that will be used to cut them.

What industrial steel paint is used?

The industrial steel paint we use at IMS is Dacrylate Aquadac 180. Available in red oxide and grey, this water-based blast primer is free of lead, cadmium, and chromium VI compounds, and it offers temporary protection against corrosion for steel constructions and cast iron.

Furthermore, the paint is fast drying, offers fast recoatability, and is resistant to mineral oils. Steel items coated with Aquadac 180 are weldable up to 25-30 microns dry film thickness.

Professional shot blasting and painting services

The basic process of steel shot blasting is easy but ensuring that it’s done safely and effectively requires significant skill and expertise. Here at IMS, we can deliver your product unpainted (shotblast only) to SA 2.5, or finish it in a choice of red or grey paint.

Contact us for more information about our shot blasting and painting services.

Posted by Craig Silvain
16th August 2023

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