When customers specify a custom color finish or need additional environmental protection, a common question comes up: Can you paint over Unistrut's Perma-Green channel & fittings?
The short answer is yes — but proper preparation and coating selection matter if you want long-term adhesion and durability.
According to guidance from Unistrut engineering, Perma-Green channel already has a high-quality factory finish similar to an automotive coating, which means it behaves differently than bare steel when applying a topcoat.
What Is Perma-Green Finish?
Perma-Green is a factory-applied protective coating designed to provide corrosion resistance and durability. Because the finish is already smooth and sealed, paints do not naturally bond to it as easily as they would to raw metal.
That means surface preparation is critical before applying any additional coating.
Best Topcoat Options
According to the engineering memo, the preferred methods for topcoating factory-painted channel are:
- Liquid coating systems
- Powder coat finishes
These are considered the best-performing options because they are thermoset finishes that provide strong adhesion and long-term durability over the existing Perma-Green coating.
For industrial or architectural applications where appearance and longevity matter, powder coating is often the most durable solution.
Using Air-Dry Paints Over Perma-Green
If a project requires an air-dry paint instead of powder coating or liquid thermoset finishes, the surface should be properly prepared first.
The recommended preparation process includes:
1. Lightly Sand the Surface
The goal is to remove the gloss from the finish — not strip it down to bare metal.
A light tack sanding creates a better mechanical bond for the paint.
2. Clean the Surface
After sanding, remove all dust and debris. If a damp cloth is used, allow the surface to fully dry before painting.
3. Apply the Paint
The memo lists the following air-dry paint systems in order of likely performance:
- Acrylic urethane
- Polyester
- Alkyd
Important Performance Consideration
One important note from the engineering guidance: air-dry paint systems applied over factory-painted channel had not been formally tested at the time of the memo. The recommendations are considered best-practice guidance rather than validated performance data.
Because of this, testing a sample section before full-scale application is a smart move — especially in demanding environments or exterior applications.
Final Thoughts
Painting over Perma-Green channel can absolutely be successful when the right preparation and coating system are used. For the best durability and adhesion:
- Use powder coat or thermoset liquid coatings whenever possible
- Properly abrade the surface before painting
- Choose high-performance coating systems
- Test compatibility before large-scale production
For critical applications, consulting with both your coating supplier and your strut system provider can help ensure long-term performance. Click here to download the technical bulletin on painting Perma-Green Channel from Unistrut Engineering.