How to protect a metal surface, such as a car, with 2K epoxy primer

Painting metal surfaces requires the right steps and careful preparation to achieve a durable and clean finish. This guide walks through how to properly use epoxy primer when painting metal (such as a car), covering everything from surface cleaning and rust removal to paint application and drying.

Watch a short video or read the instructions for using 2K epoxy primer

In this 26-second video, you’ll see how we use 2K epoxy primer as a car primer. After the video, you’ll find general written instructions for using 2K epoxy primer. You can easily find the products used in the article at the end of the page!

Why use 2K epoxy primer on a metal surface?

Maston 2K Epoxy Primer (2-component) is an excellent base coat for steel surfaces, as well as acid-resistant steel, zinc, and aluminium. It forms a highly durable and dense protective film that improves topcoat adhesion and significantly extends the service life of the entire coating system.

The product withstands heavy mechanical wear and exposure to oils, greases, and various solvents and chemicals (as splashes), making it an ideal choice for demanding applications.

2K Epoxy Primer also provides excellent corrosion protection and is suitable for both indoor and outdoor use. Thanks to its fast drying time and easy application, working with it is smooth and efficient.

Required tools and materials

• Maston 2K Epoxy Primer, Thinner, and Hardener
• Cleaning tools
• Maston Degreaser
• Sanding equipment (P180–P240 sandpaper, wire brush, flap disc)
• Brush, roller, or spray gun
• Rust Remover (if needed)
• Masking tape / paper (if needed)
• Maston Thinner for stain removal

Steps for a successful application

1. Preparation

• Choose a suitable workspace for painting.
• Mask off areas you do not want to treat, if necessary.

2. Rust removal

If there is any rust on the surface:

• Remove it mechanically (sandpaper, wire brush, flap disc)
• Use a rust remover for difficult areas if needed

Important: Epoxy does not stop active rust, so the metal surface must be completely clean.

3. Surface cleaning (very important)

Once rust is removed:

• Thoroughly clean the surface using a degreaser (Maston Degreaser)
• Wipe with a lint-free cloth
• Do not touch the cleaned surface with bare hands (skin oils will contaminate it)

Poor cleaning at this stage may cause paint failure later.

4. Sanding before painting

• Light sanding (P180–P240) improves adhesion
• Remove all sanding dust carefully (compressed air or clean cloth)

5. Mixing the 2K epoxy primer and hardener

Accuracy is essential here:

• Mix Maston 2K Epoxy Primer + Hardener according to instructions
• If mixing the full amount, pour the hardener directly into the primer can and mix thoroughly
• Alternatively, use an 80% primer / 20% hardener ratio
• Add thinner if needed (10–30% for spray gun application)

Important:

• Pot life is limited – use within 2 hours after mixing
• Only mix as much as you can apply in time

6. Application (painting)

Can be applied with:

• Spray gun (best finish)
• Roller
• Brush (for small areas)

Application guidelines:

• Apply 1–2 thin coats (maximum 2 coats total)
• Allow flash-off/drying between coats

Drying between coats:

• Recoatable with itself after 4 hours at +23°C
• With PU topcoats after 1 day
• At +10°C: 8 hours for self-coating, 1 day for topcoats

Epoxy forms a sealing layer – too thick a coat may crack or cure poorly.

7. Drying and curing

• Touch dry: 2 hours
• Handle dry: 6 hours
• Fully cured: 8 days
• Topcoat can be applied after 24 hours if needed

8. Overcoating (if required)

Epoxy is not UV-resistant long term, so it should be topcoated:

• Lightly sand (P320–P400) once fully cured
• Apply topcoat directly (e.g. acrylic or 2K Paint)

9. Common mistakes to avoid

• Painting over rust
• Poor degreasing/cleaning
• Applying too thick layers
• Incorrect mixing ratio
• Working in too cold conditions (< +10°C)

Tips for best results

• Always work in a well-ventilated area to avoid inhaling fumes
• Test the product on a small, hidden area first
• Take your time at each step to ensure a high-quality finish

By following these instructions, you can successfully paint vehicle parts and extend their lifespan. Applying a high-quality primer is a cost-effective and relatively simple way to protect old metal surfaces.

Maston products outside of Finland: please check your local retailers. Retailers are found all around Europe!