What should be done if the aluminium materials for doors and windows in coastal areas are prone to rust?

September 01, 2026
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Key points first: Pure aluminium itself does not rust (the red rust known as iron oxide). The white spots, black patches, peeling and blistering visible on aluminium profiles in coastal areas are aluminium oxidation/ white rust caused by salt spray corrosion once the surface coating is damaged. It is the metal hardware fittings that are prone to genuine rust.

High salt spray, high humidity and chloride ions carried by sea winds in coastal areas constitute the primary cause of corrosion for doors and windows. The content is divided into four sections: profile selection, surface treatment, hardware selection, installation and maintenance.

Selection of Aluminum Substrate

Priority 6063-T5/6063-T6 standard aluminum profiles

Do not purchase recycled scrap aluminium or thin-walled non-standard materials. These have more impurities and are more prone to corrosion by salt fog. The recommended wall thickness of the profile should be ≥1.4mm (for exterior doors and windows, it should be ≥ 1.6mm)

Try to avoid direct contact between aluminium and different metals. When aluminium is directly in contact with stainless steel, iron, or copper, and gets damp, it will undergo galvanic corrosion and quickly develop white spots. The gaskets must be separated by using EPDM (ethylene propylene diene monomer) rubber gaskets and nylon isolation gaskets.

Top priority: Surface treatment grade (significant disparity along the coast)

Grade Recommendation (from low to high, low grade techniques will be directly eliminated in coastal areas)

Not recommended: Ordinary powder coating, ordinary anodizing (adequate for inland areas, but prone to corrosion and loss of luster in coastal areas within 1-3 years)

Nearshore (5-15 km from the coast): High-quality durable powder coating

Coastal Line, Sea View Homes (0-5km, facing the sea breeze) : Fluorocarbon-coated PVDF

The PVDF fluorocarbon coating has extremely strong resistance to salt fog. Regular fluorocarbon coatings can withstand over 1000 hours of salt fog tests. It is the preferred choice for coastal doors and windows.

Strictly prohibited for use in coastal areas: Electrolytic champagne regular model, low-priced imitation steel color oxidation, poor resistance to salt spray.

Hardware accessories: The most severely affected area for rusting along the coast.

Aluminium profiles are not prone to deterioration. The hinges, lock points, handles, and sliding supports are the first to rust and become unusable.

Ordinary iron hardware and 201 stainless steel are being directly phased out.

For the offshore area, 304 stainless steel hardware is selected.

One-line sea view, island: Upgraded 316 stainless steel hardware (most resistant to chloride ions, the top choice for those with a sufficient budget)

Minor detail: The screws are uniformly of the same material-stainless steel screws. Do not use stainless steel profiles with galvanized screws.

Sealing strips: We use EPDM (Ethylene Propylene Diene Monomer) rubber strips. PVC strips tend to age and crack quickly at the seaside, and seawater and moisture seeping in accelerate corrosion.

Installation structure design to reduce the chance of corrosion

Outer frame with reserved drainage holes

Rainwater and condensate accumulate inside the profile cavity. The saltwater, after prolonged exposure, causes preferential corrosion of the interior. The drainage holes are unobstructed. An anti-dust and anti-seepage cover can be added to prevent seawater waves from directly flowing in.

The sealant used is a weather-resistant silicone marine-grade sealant. Avoid using ordinary glass glue. It may cause cracking and water seepage in the short term. The internal and external seams are completely sealed to prevent salt spray and moisture from penetrating into the profile cavity.

Avoid having doors and windows facing the unshielded sea wind for an extended period. If conditions permit, install sunshades and canopies to reduce the direct impact of sea spray on the profiles.

Daily maintenance plan (to extend service life)

Regular cleaning (essential)

Clean the surface of the profiles with water and a neutral detergent every 1-3 months, removing the attached sea salt crystals.

The salt on the surface remains in a state of continuous absorption of moisture, causing corrosion throughout the day and night. Even the best coating will gradually deteriorate if it is not cleaned regularly.

Prohibited: Strong acid and alkali cleaners, steel wool polishing (scratching the coating= loss of protection)

If any scratches or dents are found on the coating, immediately apply the corresponding repair paint for reapplication. The exposed aluminium surface will soon develop white rust. Check the drainage holes and make sure they are not blocked by sand or seaweed.

White spots/corrosion have already appeared. How to remedy this situation?

Minor white spots, surface oxidation: Wash with clean water, dry, and apply a thin layer of the same color fluorocarbon paint for repair;

Coating bulging and peeling: Simple repair measure are of limited effectiveness. Corrosion will continue to spread downwards;

If the corrosion penetrates the cavity, in severe cases, it is recommended to replace the profile locally.

What should be done if the aluminium materials for doors and windows in coastal areas are prone to rust?

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