Many coating failures originate not from poor materials or insufficient thickness, but from invisible defects at the interface between steel and coating. This presentation focuses on surface preparation as the foundation of corrosion control, emphasizing four measurable parameters: surface cleanliness, residual dust, surface roughness, and soluble salt contamination. Corrosion begins when moisture, oxygen, and salts reach the steel surface and create localized electrochemical reactions. Even low levels of residual chlorides or sulfates can cause underfilm corrosion, leading to blistering, adhesion loss, and early failure. These issues cannot be resolved by coating selection alone. Abrasive blasting remains the most effective way to control surface conditions. However, different abrasive materials produce different outcomes. This presentation compares commonly used abrasives such as slag, steel grit, and garnet across performance factors including cleaning effectiveness, dust generation, roughness profile, and salt retention. The aim is to shift the view of surface preparation from a procedural requirement to an engineering decision. When blasting is guided by surface standards and supported by the appropriate abrasive, coating systems can achieve higher reliability, improved long-term performance, and lower total maintenance cost.
