Picking Grit Size For Sandblasting

 

When it comes to sandblasting, selecting the correct grit size is crucial for achieving the desired results. Different projects require different grit sizes to effectively remove surface contaminants or prepare a surface for coating. But how do you know which grit size to choose for your sandblasting project?

What is Grit Size?

Grit size refers to the size of the abrasive particles used in the sandblasting process. It is typically measured in microns or mesh size. The higher the grit size number, the finer the abrasive particles.

Factors to Consider

When determining the appropriate grit size for your sandblasting project, consider the following factors:

Surface Material

The material of the surface being blasted will influence the grit size selection. Softer materials may require a finer grit size to prevent damage, while harder materials may need a coarser grit size to effectively remove contaminants.

Project Goal

Consider the goal of your sandblasting project. Are you looking to remove rust, paint, or scale? Or are you preparing the surface for a new coating? Different goals may require different grit sizes for optimal results.

Speed vs. Precision

Finer grit sizes are ideal for achieving precision and detail, but they may take longer to complete the job. Coarser grit sizes, on the other hand, are more aggressive and can work faster but may be less precise.

Common Grit Sizes

Common grit sizes for sandblasting range from 20 to 1200 mesh. Here are some general guidelines:

  • 20-50 mesh: Heavy-duty cleaning and surface preparation
  • 60-100 mesh: Removing paint, rust, and scale
  • 120-200 mesh: Surface finishing and light cleaning
  • 220-1200 mesh: Fine detail work and polishing

Consult with Experts

When in doubt, it's always best to consult with sandblasting experts or suppliers. They can provide guidance based on your specific project requirements and help you select the right grit size for optimal results.

Remember, choosing the right grit size for sandblasting is essential for achieving a successful outcome. By considering the surface material, project goal, and desired level of precision, you can ensure that your sandblasting project is completed efficiently and effectively.

 

How do you pick a grit size?
A quick and simple answer is to pick a maximum grain size that is about equal to the thickness of the coating being removed.  So if what you are trying to remove is 1.6 mm thick (.063 inch), you would choose a 12 grit.  A bit finer size is often used as well, because you get better coverage as the finer particles fil into grooves, cracks, voids in the surface that the larger particles will not fit into.
A more detailed answer involves selecting a grit size based on the surface profile you are attempting to achieve on your substrate.  A quick guide can be found here.
Keep in mind that the more rounded a particle is, the more contact area it has with your substrate, and this can speed up cleaning rates.  Glass bead is a good example of a cleaning abrasive, whereas the more angular and blocky aluminum oxide particle is useful for actual surface preparation.  (Where you want the abrasive to leave a surface profile for a future coating).