Blast profile, also known as surface profile, is the roughness or texture created on the steel surface after abrasive blasting.
Abrasive blasting is a process used to prepare surfaces, often steel, before applying a protective coating. It involves forcibly propelling abrasive materials against the surface. This process not only removes contaminants like rust, mill scale, and old paint but also imparts a specific texture to the substrate. This texture is the blast profile.
Understanding the Blast Profile
The characteristics of a blast profile include:
- Peak Height: The distance from the bottom of a valley to the top of a peak.
- Peak Density: The number of peaks within a given area.
- Surface Roughness: The overall irregularity of the surface.
These characteristics are influenced by several factors during the blasting process:
- Type of abrasive material used (e.g., grit, shot, slag).
- Size and shape of the abrasive particles.
- Velocity of the abrasive impact.
- Angle of the abrasive stream.
- Hardness and type of the surface being blasted.
Why is Blast Profile Important?
According to the provided reference, abrasive blasting creates a profile that "promotes effective coating adhesion." This is a critical function:
- Mechanical Anchoring: The peaks and valleys of the profile provide a greater surface area and create microscopic anchors that the coating can grip onto. This mechanical interlocking significantly improves the adhesion of paints, coatings, and linings to the steel surface.
- Surface Area: A rougher surface (higher profile) generally has a larger surface area compared to a smooth one, allowing for better physical contact between the coating and the substrate.
- Uniformity: A consistent and appropriate blast profile across the entire surface helps ensure uniform coating thickness and performance.
Without the correct blast profile, coatings may not adhere properly, leading to premature peeling, blistering, or failure, compromising the long-term protection of the steel from corrosion.
The required blast profile is usually specified by coating manufacturers or industry standards, often measured using instruments like profile gauges or comparator plates.
