The Lingga Wreck contained a large quantity of wrought iron in the form of blades or bars and cast iron in the form of woks or cauldrons. This comes as no surprise. Most documented shipwrecks with a primary cargo of Chinese ceramics also carried iron. The 13th century Java Sea Wreck, a Southeast Asian lashed-lug ship, contained nearly 200 tonnes. The Nanhai No.1 Wreck, a Chinese junk of the same period, carried much more. The iron rusts over time, entrapping sand, coral, and any ceramics that are in contact with it. Eventually the large lumps of iron concretion come to resemble a reef. It is virtually impossible to remove entrapped ceramics from a concretion without causing breakage.
Until the 14th century, China was the only country possessing the technology to manufacture cast iron. This material is not suitable for tools or weapons as it is brittle. However, as a great conductor of heat, cast iron is eminently suitable for cooking vessels.
The wrought iron was often inferior to that made in many parts of Southeast Asia, however the Chinese had mastered a continuous production process which made their product much cheaper to manufacture. From the shipwreck evidence, tapered rectangular bars were usually stacked in conical bundles, wrapped in a coarse fabric or leaves and tied with rattan. There is some evidence to suggest that a lime compound was smeared over the iron bars to limit corrosion. The conical bundles were stacked end-for-end in the ship’s hold. At the final destination the bars were used as stock for blacksmiths, being hammered into swords, spearheads, knives, farming implements, and tools of various types.
The largest iron manufacturing centres by far were at Xingzhou and Zizhou, Hebei province, in the far north of China. Five medium sized centres were situated in the surrounding northern provinces of Henan, Shangxi, Shandong and Jiangsu. There was relatively little production in the south of China. Smaller centres could be found in Yuanzhou in Jiangxi province, and in Yingzhou in Guangdong province. There were ten more southern production centres in Guangdong, Fujian and Guangxi provinces, but their output was not high enough to feature on official receipts of the period (Wagner 2008: 299).
It is hard to say whether iron production in southern China, near key ports such as Guangzhou and Quanzhou, was sufficient to meet domestic and overseas demand, or whether supply had to be supplemented by shipments from the north. With the massive iron cargoes that were being shipped to Southeast Asia, it is quite possible that northern production was tapped.
3.2: Copper Ingots
Several large metal ingots were recovered from the Lingga Wreck. They weigh between 6 and 10 kg each and through chemical analysis, have been found to be 97.5% copper. A sand mould has been used to cast the ingots in a slightly tapered rectangular shape. Chinese characters have been cast onto the upper surface, while some have characters etched into the sides as well.
The cast characters on one ingot have been identified as XX場銅拾X with the first two and last characters being illegible (Tai Yew Seng, personal communication, 2018). The legible characters translate to “copper mine”, "[a certain type of] copper”, and “ten [weight unit]". The primary unit of weight during the Song period was the catty, equivalent to 590 g. Ten catties would be 5.9 kg, very close to the weight of this ingot.
There were at least 27 known copper mines in Guangdong Province, southern China, during the Song period (Tai Yew Seng, personal communication, 2018). Very similar ingots were recovered from the Pulau Buaya Wreck (Ridho 1989: 77). They weighed about 4.6 kg and had a copper content of 99.1%. However, they did not have any cast or inscribed characters on their surface. Another copper ingot of similar shape, weighing approximately 7.2 kg, was recovered from the 13th century Java Sea Wreck (Mathers & Flecker 1997: 87).
3.3: Copper Alloy Artefacts
Copper alloy artefacts include Chinese coins, anklets, and bracelets. With a diameter of 32 mm the coins are larger than typical ‘1 cash’ copper coins, giving them a value of ‘2 cash’. The various types are discussed in detail in Chapter 5 - Dating.
The anklets, or perhaps arm-bands, are up to 90 mm in diameter, and do not form complete circles. This allows them to be spread apart a little to facilitate wearing. Identical anklets were found on the early 12th century Flying Fish Wreck, where they were either loose on the seabed or stored inside stoneware jars. The Flying Fish anklets are almost pure copper, with a content of 99.7 percent (Flecker, forthcoming).
Coils of copper alloy wire, typically with ten loops each, have finer wire wrapped around the outer loops. The primary wire has been wrapped around a mandrel in perfect circles to make what appear to be bracelets. They are too small for adults to wear so may have been intended specifically for children. As the fine wire binding is decorative, they cannot simply be a raw material.
The Lingga Wreck gongs are approximately 42 cm in diameter. There is no central protuberance, or boss. Eight identically shaped gongs were found on the Pulau Buaya Wreck, however they are considerably smaller at 27 to 29.5 cm (Ridho 1989: 79). Many similar gongs of 41 to 43 cm diameter were recovered from the 12th century Tanjong Simpang Mengayau Wreck, a Chinese junk that sunk off northern Sabah (Sjostrand 2006).
According to Dr Tai Yew Seng (personal communication, 2018), there was an edict issued during the Southern Song dynasty strictly forbidding the export of copper or any form of copper alloy, including coins, as the empire was experiencing a deficiency. Li (2007: 110) notes that Emperor Ningzong (1194 to 1224) issued an edict prohibiting all government purchases from being conducted in metal currencies. Trading departments were ordered to use silk, porcelain and lacqerware instead, a huge boon to the ceramics industry in particular.
Bronze gongs were the only exception. They had to be registered by the responsible merchant or captain, with the place and date of registration being inscribed on each one (Dr Tai Yew Seng, personal communication, 2018). Apparently, the gongs were needed for signalling, or as an alarm system for warning of attack or fire. There are no inscriptions on the Lingga gongs however.
A flat bronze gong with an inscription on its rim bearing a date of 1231, coinciding with the Southern Song dynasty, was found during the restoration of Candi Kembar Batu in Muara Jambi, Sumatra. It measures 45 cm in diameter and has two holes on its rim. In a substantive study on Chinese gongs discovered throughout Southeast Asia, Nicolas (2009: 67) notes that this is the last of the flat gongs to be recorded. After the early 13th century, Chinese gongs began to incorporate a central boss.
Several pieces of resin were recovered from the Lingga Wreck. A sample was sent to Dr Pierre Adam, of the Biogéochimie Moléculaire Institut Le Bel in France, for analysis. The chemical distribution comprises mainly sesquiterpenoids and triterpenoids, demonstrating unambiguously that the resin originates from angiosperms and not from conifers. The triterpenoids are typical for Dipterocapaceae, and more precisely are from the dammarane or ursane series that may be associated with the Shorea genus. Shorea species occur throughout India and Southeast Asia, where the sap is tapped to form resin. It is locally referred to as dammar.
Aromatic resin was used for religious and medicinal purposes, especially in China. However, as the Lingga resin was not bound for China, nor did it originate in China, it may have been an important element of the ship’s stores, being used for caulking or hull repair. Small quantities have been found on several Southeast Asian shipwrecks of this era. Sumatra has been a common assumed origin. This may be valid for export cargoes of aromatic resin to China, but for a utilitarian function, the resin could be sourced from most of Southeast Asia.
An anvil-type grindstone is typical of Southeast Asian grindstones used over hundreds, if not thousands of years. Similar artefacts were recovered from the 10th century Intan Wreck (Flecker 2002: 61), and the early 12th century Pulau Buaya Wreck (Ridho 1989: 88). They have also been found at various terrestrial sites in Indonesia and Malaysia.
3.7: Jar of Nails
A single broken stoneware jar was found to contain an iron concretion made up of square-section iron nails. Interestingly, the exposed upper part of the concretion entrapped several candle-nuts, which must have wafted into the jar after the ship wrecked.