Is the whitening of aluminum profiles in humid conditions caused by rusting? An article to distinguish between aluminum corrosion and steel rusting
2026,08,12
Many users in daily life have noticed white powder appearing on outdoor aluminum doors, windows, and aluminum brackets, mistakenly thinking that the aluminum material has rusted. Here is a basic material knowledge correction: strictly speaking, there is no concept of "rusting" in aluminum alloy.
Rust specifically refers to the oxidation of steel to produce reddish brown iron oxide; Aluminum will automatically generate a dense aluminum oxide film upon contact with air, naturally isolating internal metals and possessing basic anti-corrosion capabilities.
White spots appear on the surface of the profile, which can be classified into three types:
The oxide film in salt spray/humid environments undergoes slight hydrolysis, forming white alumina powder, which is commonly found in non fluorocarbon spray profiles along the coast;
Electrochemical corrosion: Aluminum materials come into direct contact with iron and copper hardware, causing the formation of primary batteries in humid environments and resulting in spot white spots;
Strong acid and alkali cleaning agents damage the surface coating, exposing the underlying oxide layer.
Prevention plan: Choose fluorocarbon spraying for outdoor high humidity and coastal areas; Install insulation gaskets on hardware accessories; Only neutral detergent is used to clean aluminum materials, avoiding bleach and strong alkaline cleaners to prevent white spots from occurring at the source.
