Bronze sculptures are renowned for their durability, but surface cracking can still occur due to various factors. One primary cause is thermal stress, where rapid temperature changes cause the metal to expand and contract, leading to fine cracks over time. Improper casting techniques, such as uneven cooling or impurities in the alloy, also contribute to structural weaknesses that manifest as surface cracks.

Environmental exposure plays a significant role—prolonged contact with moisture, salt air, or pollutants accelerates corrosion and cracking, especially in outdoor sculptures. Additionally, mechanical stress from handling, vibrations, or improper mounting can create hairline fractures.

Another overlooked factor is the natural aging of the patina. As the protective oxide layer develops, internal stresses may cause micro-cracks, particularly if the patina was applied too thickly. Lastly, poor maintenance, like using harsh cleaning chemicals, can strip protective coatings and expose the bronze to cracking risks.

Understanding these causes helps collectors and artists take preventive measures, ensuring the longevity of bronze artworks. Regular inspections, controlled environments, and professional restoration are key to preserving these timeless pieces.