Though powder coatings provide a durable, visually appealing finish, the surface may experience abrasions and marks over time. When this happens, painting over powder coating can repair damage and restore a pristine appearance.
How can you paint over powder coatings to extend their lifespan? This guide will provide the tips and best practices you need to achieve the perfect professional result.
Considerations Before Painting Over Powder Coating
First, ensure you use the appropriate preparation methods and paints. Powder coating materials predominantly fall into two categories — thermoset and thermoplastic. UV curable is a lesser-used third powder coating material you might also encounter.
- Thermoset powders: Thermoset powders are the most prevalent powder coating due to durable and versatile chemical elements like epoxy and polyester.
- Thermoplastic powders: Components of thermoplastic powders, like polyamide, polythene and PVC, form a layer that does not bond to the substrate. Their melting properties make recycling easier.
- UV curable powders: These powders cure quickly under ultraviolet lights. They tend to follow infrared or convection heating stages, which allow them to melt down.
- Curing: The curing process ensures the powder doesn’t wipe off immediately. Blasting parts prepares them for coating by ensuring the surface is smooth enough for the adhesive.
- Adhesion challenges: A thick, coarse surface will produce an uneven coating, while an overly smooth one will lack the necessary keying for adhesion.
- Coating compatibility: Metals with low melting points, such as tin or lead-based alloys, may not be compatible with the heat needed for curing. Likewise, nonconductive materials like wood or plastic will inevitably repel powder coating.
How to Prepare a Powder-Coated Surface for Painting
To ensure maximum adhesion, you must have a dry, clean surface before painting over powder coating.
1. Prepare Your Surface
Scrape debris or failing material off with a bristled brush. To ensure a deep clean, apply a dirt and grease cleaner to the brush. Finally, rinse the surface and let it air dry.
2. Sand and Clean
Sanding your powder coat roughens the surface and increases its adhesion, allowing the paint to bond to it. Be sure to use a lighter grade of sandpaper and finish with solvent cleaner. This careful, thorough approach will remove excess dust from the powder coat.
3. Select Your Primer
Priming is essential for painting over powder coating. For improved adhesion, apply one full coat of primer according to the instructions on the container. Always choose a primer that bonds with rough surfaces and can seal various surfaces.
What Primers and Paints Work Best Over Powder Coating?
Choose a high-quality primer designed for strong adhesion and durability to achieve the best results when painting over powder-coated surfaces. Look for a water-based, universal product that bonds well to challenging surfaces like metal and resists rust formation. Fast drying times and a short recoat window — ideally, within an hour — will streamline your workflow. A good bonding primer will also support even coverage and long-term finish integrity, especially on materials like iron and steel.
After your primer selection, choosing paints compatible with powder-coated surfaces can be challenging. Follow the guidance below.
- Epoxy paints are ideal for high-traffic surfaces because they are chemical and abrasion-resistant.
- Acrylic paints work best for outdoor surfaces, as their UV stability can stop cracks.
- Polyurethane paints are highly durable and work well in outdoor applications that need heavier protection.
- If you’re painting over powder-coated metal, remember to choose paint designed for metal.
Powder Coating Maintenance and Repair
Despite powder coating’s durability, sun, wind and rain will always affect surfaces exposed to the elements. Regular powder coating maintenance and care will protect your surface from these external influences.
Care
Powder coating requires regular maintenance. Avoid harsh commercial cleaners containing solvents that can degrade the finish, leaving it vulnerable to staining, dullness or other damage.
Cleaning
Cleaning your powder coating with warm filtered water and an emulsifying soap is simple and highly effective. Clean critical areas at least every other week. Pressure washing is a more thorough method of cleaning powder coating large commercial exterior surfaces. This approach requires filtered water and a low-pressure setting.
Stain Prevention
Filtered water is vital for regular powder coating maintenance. Standard unfiltered water, which may include fluoride and chlorine, can leave noticeable stains on the coating’s surface.
Powder-Coated Surface Repair
Mild surface damage to your powder-coated surface may be repairable. You can apply touch-ups to small scratches, but be realistic about the extent of the damage. Considerable chipping or rust that’s beyond repair may require a complete coat removal.
Powder Coating Warranty Considerations
Reliable powder coating requires quality that meets or exceeds modern requirements. Factors like environmental conditions, material defects and workmanship can all potentially void a powder coating warranty. Consider the following when reviewing your warranty:
- Is your coverage level understandable?
- Does the warranty reflect the environmental conditions your surface will encounter?
- Does it adhere to strict standards like those from the American Architectural Manufacturers Association?
- How long is the coverage?
Keystone Koating provides a warranty of up to 20 years on projects approved by AAMA 2605. KEYCOAT20 is an ideal choice for architectural metal applications as an eco-friendly alternative to wet paint.
Powder Coating Solutions From Keystone Koating
Keystone Koating has provided quality powder coating services in Pennsylvania for over 30 years. Our skilled team members have developed tailored solutions to achieve rapid turnaround times on orders of any volume to deliver finished products.
Do you have a commercial powder coating request? Get a personalized quote today and find out how we can solve your coating needs!