1. Incomplete or inadequate drying (High risk)
Air drying at room temperature: After surface moisture evaporates, residual moisture inside or at weld seams can cause pitting corrosion within 2-4 hours.
Ambient humidity > 60%: Even if the surface appears dry, visible rust spots may appear within 6-12 hours.
Rainy weather or coastal areas: Rust may quickly reappear within 1 hour, especially in air containing chloride ions, where electrochemical corrosion is more likely to occur.
2. Proper drying but without anti-rust coating (Medium risk)
Hot air drying (120-170℃/15min): Completely evaporates moisture, preventing rust in the short term (24-72 hours).
Storing in a dry environment (humidity < 50%): Can maintain rust prevention for 3-7 days.
Exposure to ordinary air: Due to the high surface activity of metals, moisture begins to be absorbed after 3 days, gradually leading to oxidation.
3. Drying + Rust Prevention Treatment (Low Risk, Recommended)
Spraying water-based rust inhibitors or quick-drying rust-preventive oils: After forming a protective film, it can effectively prevent rust for 1-3 months;
Sealing with VCI volatile rust-preventive paper/bags: Under sealed conditions, the rust prevention period can reach more than 6 months;
Brushing with a rust-preventive primer (such as iron oxide red rust-preventive paint): Not only prevents rust, but also converts trace amounts of residual rust, providing long-term corrosion protection, suitable for reuse or long-term storage.
✅ Key Recommendation: Cleaned metal cans should be dried and rust-prevented within 6 hours to avoid accelerated corrosion from alternating dry and wet environments. The recommended combination of "hot air drying + spraying water-based rust inhibitor + sealed packaging" has achieved a rust prevention success rate of over 99% in the industrial recycling field.
