The bronze drums of Dongson - Alloying and casting technologies

By Pham V. Huong, Arts and Literary E-Magazine,
No. 478, 22 August 1999

After the fourth century BC, other drums of bronze continue to be manufactured. One finds several of them even in Ngoc-lu and at other regions of the Southeast-Asia, attesting the blossoming of this culture that archaeologists later call Dongson culture.

3.1.5. Bronze drums of Post-Dongson period

After having seen the ties existing between the metallurgy science of the period meadow-Dongson and the one of the Dongson period as well as the casting technique, it would be interesting to examine bronze drums of the post-Dongson period in order to follow their evolution.

The results of the micro-analysis of the X-ray spectra concerning a bronze drum of the fourth century of our era are given in the next table.

We can notice that the tenure of Lead is weaker than in the drum of Ngoc-lu. One also note that the decorations on the drum are a lot simpler and especially much less fine. Let's recall that this geographical area underwent from the beginning of the second century BC a crushing influence Han coming of the center of continental China.

One would be able therefore to deduce that a tenure of lead around 16% in atomic percentage in the alloy, as the one used at the dongsonian time, would facilitate the thin motive casting in relief.

On the other hand, the absence of Iron can be noticed. This absence could be owed to the absence of Ion foulness in the ores of origin, either to a more worked out alloying science, due to the knowledge in the 4th century of purification and obtention of pure metals Copper, Tin and Lead before their recombination in alloy. We bend toward this second explanation.

In this optics, an alloy containing equal parts in weight of the three metals Cu, Sn and Pb, without Fe, would be therefore adequate for the casting of objects with fine decorations in relief.

3.2. Bronze drums and geographical variances

When one examines bronze drums overdrafted in different regions since Mianmar until Indonesia, while passing by the south of China and Vietnam , one notes no without surprise that the drums carry all same motives of decoration 21. On the center of the eardrum there is always a stellar motive being able to represent the place of percussion with radiuses symbolizing directions of resonant propagation. Men and women carrying clothes and long feather hats are represented on crowns of the eardrum. Birds with long beak and long tail follow each other on other crowns. These motives are strangely the same whatever is the geographical origin of the drums.

Besides, many drums carry on the periphery of their eardrum toads by group of four either superimposed of four are called MALE DRUMS everywhere (tro^'ng in Vietnamese). Those not carrying a toad are said FEMALE DRUMS.

This identity of the visible decorations on the outside contrasts with the difference of the chemical compositions of the alloy (inside) of the drums, according to the geographical regions as we already saw it above. This fact could explain himself by the nature of the cultural exchange between peoples of the Southeast-Asia of the proto-history 22-28. If the apparent decorations were easily transferable, the metallurgy science was certainly kept in secret by smelters craftsmen of every region. MANUFACTURES OF BRONZE DRUMS WERE THEREFORE LOCAL.

4. Conclusion

X-ray Micro-spectroscopy and Raman Micro-spectroscopy were used to the studies of bronze drums of the first millennum before our era, and overdrafted in Southeast-Asia. The analysis of the results permitted to understand the alloying science and the casting technique of these hollow objects of big sizes and including particularly thin motives of decoration. The study also reflects a particular nature of the cultural exchange at the proto-historic time between peoples of this region. The undertaken analytic procedure would be perfectly applicable to some other problems that can raise by archaeology.

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