Sea-Line Epoxy Primer 4:1 Anticorrosion – Red 4:1 Epoxy Metal Primer

Sea-Line Epoxy Primer 4:1 Anticorrosion is a high-performance epoxy primer primarily designed to protect metal structures (steel and aluminum) on yachts and boats from corrosion. Its distinctive red oxide color serves as a visual coverage indicator and a traditional anti-rust pigment. This primer forms a hard, chemically resistant film that adheres strongly to the substrate and acts as a barrier against water, oxygen, and salts – the main culprits of corrosion. Sea-Line 4:1 Anticorrosion Primer is suitable for all parts of a boat made of steel or aluminum: hulls, keels, metal superstructures, tanks, and more. It can be used both above and below the waterline as part of an anti-corrosion paint system (including under antifouling).

• Properties & Benefits: It’s a two-component product – an epoxy resin base and a hardener that are mixed in a 4:1 ratio. Once mixed, the primer has a workable pot life of about 2 hours at 20°C, allowing the application of 2–3 coats before the mix begins to gel. The cured film offers excellent adhesion to properly prepared metal – the primer “bites” into the surface and fills micro-porosity, creating an ideal foundation for subsequent coatings. Anticorrosive performance is achieved through a combination of barrier properties (an impermeable epoxy layer) and active pigments (red oxide) that protect the metal. The dry film has a smooth matte finish and very good intercoat adhesion – no sanding is required between coats if you stay within the re-coating window (min. 4 hours at 20°C, max. 5 days). The cured primer is resistant to seawater, fuels, and oils, ensuring long-term protection.
• Application: The surface should be thoroughly prepped: remove any rust, old flaking paint, and degrease the area. Grit blasting or grinding to Sa 2½ (near white metal) for steel is recommended (or at least St3 power tool cleaning), and sanding plus degreasing for aluminum. Mix Components A and B in a 4:1 ratio (by volume or weight, as directed) and stir thoroughly. Allow ~5–10 minutes induction time (to start the chemical reaction) and then apply the primer by brush, roller, or spray (conventional or airless). For spraying, up to ~5-10% epoxy thinner can be added to achieve proper viscosity. Apply 2–3 even coats of primer, each about 60 μm DFT (dry film thickness) – aiming for ~120–180 μm total dry film for optimal protection. Wait at least 4 hours between coats at 20°C; the primer will become tack-free relatively quickly, facilitating multiple coats in one work day. After the final coat, allow it to cure fully (7 days at 20°C for full cure, or at least 24 hours before overcoating with another product if you plan to topcoat sooner). Note: Do not apply the primer below 10°C or in very high humidity, as such conditions can adversely affect curing and adhesion.
• Coating System & Compatibility: Sea-Line Epoxy Primer 4:1 Anticorrosion integrates well into a variety of coating systems. As the first coat (on bare metal), it provides a transition to other primers and paints. For example, you can apply an additional layer of Epoxy Lightprimer 5:1 on top if you want to build more film thickness or add osmosis protection on composite parts. Above this primer, you can apply two-component polyurethane topcoats (yacht enamels) for topsides or antifouling paints for the underwater body – the primer greatly improves the adhesion of antifouling to steel hulls. On aluminum, Epoxy Primer 4:1 is an excellent base after proper surface prep; for even better bite on aluminum, a wash primer or etch primer can be used beforehand, but it’s not strictly necessary if preparation is good. The primer is pigmented “oxygen red” for easy identification and full coverage on metal surfaces – the red color contrasts with steel, helping ensure no areas are missed during application.
• Available Sizes & Mixing: Sea-Line Epoxy Primer 4:1 comes in a 750 ml set (primer 600 ml + hardener 150 ml) – convenient for small jobs or individual parts, and a 7.5 L set (primer 6 L + hardener 1.5 L) – economical for larger areas or whole-hull priming. The resin can is sized to allow room for adding the hardener and mixing directly in the can (for smaller sets), simplifying the mixing process. Only catalyze the amount you can use within about 2 hours. The ideal application temperature range is 10–30°C; in warmer conditions the pot life will shorten. By following the instructions, this primer will provide a reliable base with long-lasting corrosion protection, preserving the integrity and value of your vessel.

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