How Sandblasting Media Affect the Anchor Pattern on Metals

Sandblasting service contractors use various media. The choices among sandblasting media include stone, plastic, silicate, metal, or organic materials. Why are there are so many options? A sandblasting medium gives a different effect on the surface. The particles’ density, hardness, size, and shape affect the result. In addition, the anchor pattern determines how well paint sticks to the surface.

What is the anchor pattern?

Before_blast_Rust_Grade_One crucial result of sandblasting is the anchor pattern. The anchor pattern is the valleys and peaks forming on a surface. It describes the roughness of the metal surface.

As you probably know, each coating material has a desired anchor pattern. The pattern allows for best coating adherence. A shallow anchor pattern will cause poor paint adhesion. You will need to apply more layers of paint to get the result you want. On the other hand, holes may develop if the anchor pattern is too deep.

How do the abrasive particles affect the surface?

The blasting medium affects the metal surface. The impact of the medium can form small craters that are invisible to the naked eye. If the cavities are very deep, the ridges of the depressions may poke through the surface of the coating. The deeper recesses will expose tiny parts of the metal underneath. If this happens, these small ridges can cause rust to develop.

Sandblasting contractors understand what a project need. They also know the anchor pattern each sandblasting medium makes.

This guide will let you know the abrasive properties of different sandblasting media. You will also learn how they affect the anchor pattern. Ready?


The shape of the sandblasting medium affects the anchor patterns. For example, round particles are less abrasive. On the other hand, a coarse medium with sharp angles may cut deeply into the metal surface. Why? Because the sharper particles can dig deeper into a metal surface than rounded particles of the same size.

Shapes can be round, sub-rounded, sub-angular, and angular. Crushed glass and coal slag are some of the coarsest media. They are angular. Plastic, garnet, and olivine are less sharp, falling into the sub-angular category. Staurolite and walnut shells are under the sub-rounded category. Silica sand and glass beads are in the rounded category.


The sandblasting industry measures the particles by their mesh size. Mesh is the number of evenly spaced holes in one square inch of screen or sieve. The industry standard gives the particle’s mesh size range of 30/60. Ninety-five percent of the particles will pass through a 30 mesh in this range. But the particles will not pass through the 60 mesh. Why is this so? Particles with smaller numbers are coarser. The higher number indicates the fineness of the particles.


The hardness of the medium affects the depth of the dent or etching on a surface. Softer media will not create any mark. Otherwise, it will only produce a slight anchor pattern. But some sandblasting contractors often use extremely harsh abrasives. This approach can get the job done faster. However, harder abrasives can be brittle. As a result, they can break on impact. When this happens, the medium reaches the surface with less energy. The consequence? The process must be repeated.


Density is very critical in sandblasting. Dense particles result in higher pressure upon impact. Therefore, the particle will push deeper into the surface. In addition, the thicker materials transfer more kinetic energy. Thus, using a denser medium ensures better cleaning.

On the other hand, less-dense particles can compress when they hit another object. In this case, the medium absorbs the impact of the collision. When this happens, the cleaning becomes less efficient.


Velocity has an impact on the anchor profile. But did you know that the sandblasting contractor controls the speed? The contractor can adjust the acceleration or speed of the medium. They can also change the pressure according to the surface they will clean.

Now you know the effect of a blasting medium on the anchor pattern. You can use this guide anytime. It will help you choose the suitable abrasive material for the job. Keep this in mind: the anchor pattern the particles make on the metal surface determines how well the coating will adhere.