What is the weakness of Corten steel ?

Fencing made of corten steel is an architectural application. Heterogenous colouring caused by atmospheric conditions and oxide stains are some of its disadvantages. "Some circumstances require a solution to the inherent disadvantages of the Corten steel

Corten steel is characterised by its low maintenance, unlike, for instance, a paint coating. Over time, the surface oxide layer of weathering steels becomes more and more stable, unlike paint finishes, which gradually decompose due to atmospheric agents and thus require frequent maintenance.

One common issue with naked Corten steel is that the oxide is water soluble, particularly in the early stages of oxidation. Consequently, the rainwater that washes the steel surface also drags certain contents of dissolved oxide, which result in reddish or rust stains in the water deposition zones.