Metal sculptures, especially those left untreated, are prone to tarnishing due to exposure to moisture, air, and pollutants. To preserve their aesthetic appeal, here are the most effective ways to prevent surface tarnishing:

1. Regular Cleaning: Gently wipe sculptures with a soft, dry cloth to remove dust and moisture. Avoid abrasive materials that can scratch the surface.

2. Protective Coatings: Apply a thin layer of wax or lacquer designed for metals. These coatings create a barrier against oxidation without altering the sculpture’s appearance.

3. Controlled Environment: Display sculptures indoors or in low-humidity areas. If outdoors, use covers or shelters to minimize exposure to rain and humidity.

4. Anti-Tarnish Strips: Place these near sculptures to absorb airborne sulfur and other corrosive elements that cause tarnishing.

5. Avoid Direct Handling: Oils from skin can accelerate tarnishing. Wear gloves when handling untreated metal sculptures.

By following these methods, you can significantly extend the lifespan and beauty of untreated metal sculptures.