Outdoor bronze sculptures are prone to surface corrosion due to exposure to weather elements. To effectively repair and restore them, follow these proven methods:

1. Gentle Cleaning: Start by removing dirt and debris with a soft brush and distilled water. Avoid harsh chemicals that may damage the patina.

2. Lemon Juice and Baking Soda: For mild corrosion, create a paste of lemon juice and baking soda. Apply gently with a soft cloth, then rinse thoroughly.

3. Professional Wax Coating: After cleaning, apply a high-quality microcrystalline wax to protect the surface and slow future corrosion.

4. Electrolysis Treatment: For severe cases, consider professional electrolysis treatment which safely removes corrosion without damaging the bronze.

5. Patina Restoration: Skilled conservators can recreate the original patina using chemical solutions matched to the sculpture's age and style.

6. Regular Maintenance: Establish a biannual inspection and cleaning routine to prevent serious corrosion buildup.

Always test any cleaning method on a small, inconspicuous area first. For valuable or historic sculptures, consult a professional conservator to ensure proper treatment that preserves the artwork's integrity and value.