It was believed that Chinese civilization developed in the Central Plains area of the Yellow River. In the last 50 years, however, major excavation have been undertaken in Sichuan, Shaanxi, Shanxi, Hebei, Shandong, Henan, Chongqing and Hubei, areas thought to be primitive and devoid of historical context. Our understanding of Chinese history and its contributions to the Bronze Age was fundamentally changed with recent discoveries. In China, the Bronze Age was assumed to have started around 1900 BC, although the earliest dated bronze objects in China are from approximately 3000 BC, similar to the time Greece began using bronze. For comparison, the pre-Columbian civilizations of the Americas had bronze technology in 1000 AD.
The high temperatures of the Neolithic kilns used to fire pottery were hot enough to melt metals from stone; pottery kilns found near Xi’an could maintain temperatures at 1400 °C as early as 5000 BC. Casting was a more natural progression for the Chinese who had a long history with pottery and jade carving since the Neolithic period. The Europeans were far more reliant on hammering and working the metal into shape during their Bronze Age. For this reason, scholars believe Chinese artisans were able to develop bronze without the influence of other cultures, suggesting an independent Chinese discovery of bronze.
Bronzes from ancient civilizations provide insight into the cultures of 4000 years ago. There is great appreciation for the progression of metallurgical processing techniques that evolved over thousands of years. The materials and metallurgical techniques can be studied to provide information about material structure and the technology used to manufacture the objects.
Investigations of structure and chemistry are useful for documentation as well as for preservation and restoration, establishing better estimates about timelines, place of origin and probable use. Several of the artifacts in the Tseng collection were examined in the Advanced Materials Laboratory at California State University Northridge (College of Engineering). Most of the samples were too large to directly place in the chamber of a Scanning Electron Microscope, so analysis was done on surface deposits removed with carbon tape. The Chinese objects included a bronze vessel with jade dragon handles and a copper/gold lid, a bronze guang with animal characteristics, and a bronze ding.
For each sample, micrographs were taken, spectrum analyses were obtained and elemental compositions were calculated. Actual bronze alloy percentages vary significantly in the amounts of copper (90% – 50%), tin (10% – 50%), lead, silver and iron used for ancient bronzes. Many of the artifacts demonstrate thin walled casting and unique surface decoration. The ancient Chinese developed a most unusual casting method called the piece mold process where surface decoration could be made by carving into the mold or into the model. The Tseng collection provides possibility for metallurgical examination and collaboration with archaeologists and conservators from other institutions on a cultural and scientific level, giving an unprecedented opportunity to explore the art, material culture and spiritual life of ancient China. Read The Fall White Paper