Untreated metal sculptures are prone to oxidation, which can tarnish their appearance and structural integrity over time. Fortunately, several effective methods can help prevent surface oxidation and preserve these artworks.

1. Wax Coating: Applying a thin layer of wax, such as microcrystalline or beeswax, creates a protective barrier against moisture and air. This method is non-toxic and easy to reapply.

2. Oil Treatment: Regularly coating the sculpture with mineral oil or WD-40 can repel water and slow oxidation. This is ideal for outdoor sculptures exposed to the elements.

3. Clear Sealants: Using a clear acrylic or polyurethane sealant provides a durable, invisible shield. Choose a UV-resistant formula for outdoor pieces to prevent yellowing.

4. Controlled Environment: Displaying sculptures indoors with stable humidity (below 50%) significantly reduces oxidation risks. For outdoor pieces, consider covered areas or shelters.

5. Regular Cleaning: Gently removing dirt and pollutants with a soft brush and mild soap prevents corrosive buildup. Avoid abrasive tools that could scratch the metal.

6. Anti-Corrosion Sprays: Commercial anti-rust sprays offer quick protection, especially for intricate designs where manual coating is challenging.

For long-term preservation, combining these methods—such as cleaning followed by wax or oil application—yields the best results. Always test treatments on a small area first to ensure compatibility with the metal type.

By implementing these strategies, artists and collectors can maintain the original beauty of untreated metal sculptures for years to come.