PRESSURE
SANDBLASTING GUIDES
Sandblasting creates the surface profile a paint or coating needs in order to key on; done wrong, the coating lifts within a short time. This section covers abrasive selection, the equipment decision, surface profile measurement and operator safety.
5 guides · from the USEL engineering team
Why surface profile is measured
The purpose of sandblasting is not to clean the surface but to create a measurable roughness profile. Paint keys mechanically into the peaks and valleys of that profile. If the profile is too shallow the coating will not hold; if it is too deep the peaks break through the paint film and corrosion starts there.
ISO 8503 defines that profile through peak-to-valley height (Rz) and grades it with a comparator as coarse, medium or fine; Ra is a separate parameter used in general roughness measurement and is not part of ISO 8503. The coating manufacturer gives the target Rz range on the technical data sheet — sandblasting is carried out to hit that figure, not to run "until the surface looks clean".
The main variable that sets the profile is the type and grain size of the abrasive. Garnet, silica sand, aluminium oxide and glass bead leave completely different profiles at the same pressure; substituting one for another changes the result.
Capacity and safety
The most common mistake in sandblasting systems is choosing a compressor smaller than the air the blast gun consumes. When pressure drops the profile becomes shallower, the job takes longer and the result turns inconsistent. Compressor capacity has to be calculated from the nozzle diameter of the gun.
The cabinet versus portable decision, in turn, is about part size. A cabinet reclaims the abrasive on repetitive small parts and keeps the dust under control. A portable system is the only option on site and on large structures, but dust management and PPE discipline are critical there.
When working with silica-bearing abrasives, respiratory protection is not negotiable. Silicosis is an irreversible occupational disease and the exposure only shows itself years later.
PRESSURE SANDBLASTING GUIDES
Surface Profile Ra and Rz — A Guide to the ISO 8503 Standard
The critical concepts in surface preparation before painting, coating and bonding. The difference between Ra (average roughness) and Rz (peak-to-valley roughness), measurement methods, and which profile suits which coating.
Choosing an Air Compressor for an Industrial Workshop
The right compressor for sandblasting, CNC and waterjet machines — capacity, pressure, receiver size, oil-free versus lubricated, screw versus piston. An undersized compressor reduces workshop output to nothing.
Cabinet Blasting or Portable Blasting? — A Decision Guide
The differences between enclosed cabinet blasting and portable (site) blasting machines. A comparison in terms of production volume, part size, working conditions, PPE and waste management.
Restoration and Antique Sandblasting — Surface Preparation for Works of Art
Sandblasting in the restoration of historic buildings, sculpture and heritage objects — choosing a gentle abrasive, low-pressure techniques and the approach that protects the historic fabric.
What Is Pressure Sandblasting? A Surface Preparation Guide
Portable pressure sandblasting machines, abrasive types (silica sand, garnet, aluminium oxide), pressure setting, PPE and silicosis protection — the industrial guide to surface preparation.
Explore portable pressure sandblasting systems by capacity and field of use.
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