The most critical factor determining the quality of a powder coating result is not the spray gun or the oven — it is surface preparation. Experts say this stage accounts for 70% of the overall process quality.
Why Is Surface Preparation So Important?
Metal surfaces contain invisible contaminants: grease, moisture, oxide layers, and dust. Paint applied over these impurities will begin to blister, crack, and peel in a short time. No matter how high-quality the coating material is, achieving a long-lasting result on an unprepared surface is simply not possible.
Degreasing
The first step is always degreasing. During manufacturing, metal surfaces pick up machining oils, anti-rust sprays, and fingerprint oils. Alkaline chemical solutions or steam degreasing completely remove these residues.
- Surfaces that are not degreased will begin to blister within 6–12 months
- Chemical degreasing gives deeper and more uniform results than mechanical cleaning
- The surface must be rinsed with pure water after treatment
Phosphating
Phosphating is a process in which the metal surface is coated with a very thin layer of phosphate crystals through a chemical reaction. This layer serves two critical functions:
- Corrosion resistance: Slows moisture and oxygen penetration, preventing rust
- Adhesion strength: Significantly improves the bonding of powder coating to the metal
The difference in service life between metal coated without phosphating and metal coated after phosphating can be 3 to 5 times.
Sandblasting
Sandblasting is a process in which abrasive particles are blasted at high pressure onto the metal surface to create a roughened profile. This roughness gives powder coating particles more contact points on the surface.
- It is especially necessary for previously painted or rusty surfaces
- Sa 2.5 or Sa 3 grade sandblasting provides the best adhesion
- Preferred for thick profiles and structures rather than thin sheet metals
Surface Preparation at Teknosan Boya
Serving in Bursa since 1999, we put every workpiece through a complete surface preparation process before coating. With our phosphating line and sandblasting units, we maximize the service life of your powder coating.
For questions, contact us.