The short answer is: it depends, but generally, it's not recommended without some form of protection. While modern steel outdoor furniture is often designed to withstand the elements, leaving it completely unprotected will shorten its lifespan significantly.
The primary enemy of steel furniture is rust. Even "weather-resistant" steels like some stainless steels or powder-coated carbon steel are not entirely immune. Constant exposure to rain, snow, humidity, and sun will eventually compromise protective coatings. Moisture can seep into tiny scratches or joints, starting the corrosion process from within. Sunlight can degrade and fade powder coatings over time, making the steel vulnerable.
For urban settings, additional factors like acid rain, pollution, and bird droppings can accelerate wear and corrosion. Furniture left on a balcony or rooftop faces these intensified elements.
To maximize the life of your steel urban furniture, consider these protections:
1. Use High-Quality Covers: A breathable, waterproof cover is the simplest protection from rain and sun.
2. Apply Protective Wax/Oil: For untreated or lightly treated steel, periodic application of a protective wax or oil can create a water-repellent barrier.
3. Choose the Right Type: Opt for furniture made with 304 or 316 grade stainless steel or with a thick, high-quality powder-coated finish for better inherent resistance.
4. Perform Regular Maintenance: Clean furniture regularly with mild soap and water. Inspect for chips or scratches in the coating and touch them up immediately with matching paint to prevent rust spots.
In conclusion, while you *can* leave steel furniture outside, doing so without any protection is a gamble. Proactive care and simple protective measures are crucial investments to preserve its appearance and structural integrity for years to come.