The Metals Of Antiquity – Lead

Lead Water Pipe In Herculaneum

If you consider the contribution of plumbing to human life, the other sciences fade into insignificance. – James P. Gorman

Plumbing, plumbers and lead go way back. In fact, the profession and its professionals can thank the soft, pliable metal for their name. The Latin word for lead is 'plumbum'. Interestingly, other 'plumb' words like the surveying terms 'plumb bob' and 'plumb line' also derive from 'plumbum'. Plumb bobs are an ancient surveying tool and were used by cultures like the Egyptians and Romans to help build some of their remarkable, and remarkably square/straight, structural creations. The earliest plumb bobs were made from stone and other materials like wood that could be shaped into the desired smooth symmetrical shape but eventually came to be made from heavier materials, notably lead and subsequently bronze. They're still used today, despite the relatively 'recent' invention of the spirit level.

Some Of The Oldest Examples Of Lead Use

Like other metals of antiquity, some of the oldest examples of lead artefacts have been found in what is now Turkey. A lead-containing statue uncovered there has been dated to around 6,500 BC. Some lead beads and various other lead items found in a burial site in Çatal Hüyük date back to 6,400 BC. A lead bangle at Yarum Tepe (northern Iraq) comes from the 6th millennium BC, as does a conical lead piece found near Mosul (Iraq). A bit younger, and dating to the 4th millennium BC, are some lead items found in Turkmenistan.

Lead has been identified as an ingredient in ancient glass, and in pottery glazes, particularly those of Egyptian origin. It was also used to create beads, jewellery, household utensils, ornaments and decorations, statues, and building materials. From the middle of the 2nd millennium BC, the Assyrian and Babylonian Kingdoms in particular used soldered lead sheeting in their buildings, and molten lead to fasten bolts. Gladiators wore a gadget called the cestus AKA lead knuckles during their fights. The ancient Greeks discovered that lead is non-corrosive and used it to coat boat hulls, a practice the Romans also adopted, and one that continues today.

Various lead objects recovered from the cargo of ancient shipwrecks (ie Uluburun) include weights for fishing nets, ingots, and lead-filled hollow cast bronze weights for balancing scales. The scales are believed to have belonged to merchants on board the vessels, and would have been used for measuring out products for sale.

By around 2,000 BC, the Chinese were using lead to forge coins, as were the Greeks and Romans. Examples of lead in bronze artefacts from the Erlitou culture (1,900 to 1,500 BC) have also been unearthed there. Likewise, lead drinking vessels from the Yin/Shang Dynasty dating to the same period have been found, ironically in graves but more about lead toxicity later.

We also know lead and other minerals were widely used in alloys with copper to produce various types of bronze. Bronze objects containing as much as 30% lead have been found, whilst Greek and Roman bronze is known to have contained a lot more lead than that produced in some other cultures. Some alloys were probably unintentional and came about courtesy of natural contamination of the ores used to smelt copper but quickly became intentional as the advantages of these copper alloys over pure copper were recognised.

As an aside, some of the earliest instances of significant environmental lead pollution have been linked to the smelting of lead-containing copper ores 1.

Lead And Silver Also Go Together ….

Although there are reports of a 'lead mountain' on the coast of the Red Sea called Gebel Rosas and various other lead mines throughout Egypt, a lot of early lead production is believed to have been a by-product of silver smelting. Silver was a highly valuable and sought after commodity in the ancient world. Native silver deposits are rare though so the next best option would have been to use an ore that contains significant amounts of silver such as galena. Ancient lead / silver ore mines are scattered across Europe in addition to the ones in Egypt.

Today galena is a major source of lead and one that also produces a lot of silver but in the ancient world, the silver was almost certainly the primary target. Tests on ancient silver artefacts show they have lead concentrations of >0.05%, indicating they were smelted from lead ores like galena. The lead was a by-product but one that quickly became useful in its own right. Unfortunately however where there is extensive lead use, lead contamination and health problems usually follow.

Ancient Lead Pollution

Even 4,000 years ago, lead use was not without its environmental drawbacks! Scientists have found that historically levels of lead in the environment rise and fall in sync with human lead production 2. Notably, two significant peaks (that coincide nicely with periods of intense Roman activity) occurred across Europe in the middle of the 3rd century BC and circa 120 AD. At the height of these peaks, environmental lead concentrations reached levels that were some 10 times higher than background levels!2 Interestingly (but unsurprising given its association with lead ores), researchers have found that antimony levels also increased alongside the lead so inhalation of heavy metals would have been common at the time.

The Heady Heydays of Lead

Lead use was firmly entrenched in ancient society by the time the Romans came along but they were the ones who turned it into a major industry. The 2 noticeable spikes in ancient environmental lead concentrations mentioned above bear silent witness to the Empire's huge increase in lead smelting and lead use. The first spike aligns with a time of Roman expansion and conquest, when lead bullets and balls were slung from slingshots and cannons (lead was too soft for swords and spears), and boiling hot liquid lead was poured down on marauders from fortress walls. The second one dovetails nicely with a huge thriving Roman society in which lead was an all-important commodity.

The Romans were in fact heavily reliant on lead. One of its best-known uses was in the construction of their amazing plumbing and water systems. They created mile upon mile of lead piping that was soldered together with lead-based solder, and used it to transport water and sewage across their empire. Completely intact sections of the pipe and plumbing system still exist today, testament not just to the non-corrosive properties of lead but also the engineering skills of the Romans. Baths were also commonly lined with lead to prevent corrosion, and it was used as a roofing and building material.

Lead and lead-lined vats were standard issue for winemakers of the day because Romans loved the sweetness of their lead acetate infused wine. It leached into the crushed grape liquid during the boiling process, or was added to sitting wine as a flavour enhancer. In contrast, wine made in copper and copper alloy vats was nowhere near as popular because it had a rather 'disagreeable' taste. It would however have been the far healthier option!

Lead and its tin alloy pewter were also widely used to make home wares like drinking vessels, tableware and cooking implements. It was a common additive in cosmetics, paints, enamels, coins, toys, and many other items used in daily life.

In short, lead was one of those 'must-have' commodities that Roman life depended on and by the time the 1st century AD rolled around, the Empire was producing some 80,000 tonnes of it annually. Here's a quick snapshot of how they used it!
  • They drank their lead sweetened wine (and also water supplied via lead pipes) from lead and pewter drinking vessels.
  • They frequently ate lead acetate-sweetened food cooked on lead braziers, served in lead and pewter dishes.
  • They bathed in lead lined bathtubs likely filled with water that had been piped in through lead plumbing.
  • The cosmetics and some of the jewellery they wore often contained significant amounts of lead.
  • Some of their coins had lead alloys in them, or were made from lead itself.
  • Their buildings often contained multiple lead and lead-based components (structural materials, paint, decorations etc).

Etcetera! In fact, you could say many Romans, particularly the more affluent ones, exposed their bodies (inside and out) to rather a lot of lead! Knowledge about, and acceptance of, lead poisoning was clearly a long way in the future!

Speaking of lead sweeteners - the Roman Apician Cookbook contains 450 recipes, at least a fifth of which are enhanced by lead 'flavouring'.

Lead In The Middle Ages

It turns out Romans weren't the only one who liked lead flavoured food; 'sugar of lead' ie lead acetate was a popular culinary additive throughout the Middle Ages too, and beyond.

Other forms of lead use continued into the Middle Ages, including an increasing popularity as a roofing material – a few famous buildings still have lead roofing today. It was also used for framing roof installations, and as a sealant between stone blocks. Lead frames held together the stained glass window panels, and some of the paints used in the stains had lead in them.

Pewter dishes remained popular throughout the period, as did lead-based paints, glass, cosmetics, and a range of other items. When firearms were invented in the middle of the 15th century, it didn't take long for lead shot to become the ammunition of choice. Another 15th century invention, the printing press, used moveable type made from lead.

Lead In The Modern Era

Fast-forward to more recent times and lead still had a wide range of applications. In 1921, a couple of clever chaps discovered that adding tetraethyl lead to petrol produced a fuel that was far kinder to motor vehicle engines. By the end of the decade, all major petroleum companies had jumped on board and were producing leaded petrol. For the better part of the ensuing half-century, lead-propelled motor vehicles around the globe discharged their exhaust fumes into the atmosphere. Finally, by the 1970's awareness of the fuel's toxicity to humans and the environment was common knowledge and the industry was forced to come up with lead-free alternatives. Many countries began phasing out leaded fuel and developing vehicle engines that could use unleaded petrol. By the early 2000's most countries had completed transitioned, and banned leaded fuels. In 2019, the Partnership for Clean Fuels and Vehicles 3 announced that just 2 countries still used leaded petrol but even in those countries, there was progressive switching to unleaded fuel.

However, the motor vehicle industry continues to be one of the biggest users of lead by way of lead-acid batteries. Today these batteries account for around 80% of global lead use. Lead-acid batteries are also used for power storage with renewable energy systems, and as backup emergency power for critical operations ie medical and computer facilities.

Lead compounds like lead oxide are used in corrosion-resistant coatings for steel and iron. Ship's hulls for instance are still coated in it to prevent them corroding. Communication and power cables destined for watery environments likewise are typically coated / sheathed in protective lead coatings.

Adding lead oxide to glass increases the refractive properties of the glass and produces an expensive type of glass called crystal that most people associate with high-end glassware. The higher the lead content, the rarer and thus more expensive the crystal becomes. Most crystal today however contains either far less lead per se or a significant portion of it has been replaced with 'safer' oxides. These types of crystal are called 'crystal glass' or 'crystalline glass' to distinguish them from the higher lead containing crystal. Only a few big name crystal manufacturers like Waterford and Swarovski still produce lead crystal. Research 4 5 shows that certain types of drinks (alcoholic and citrus based liquids) stored in lead crystal for longer than a few hours do begin to absorb lead from the crystal. However, the more the crystal is used, the less lead it leaches 5.  Lead crystal is still occasionally used in optical instruments and camera lenses.

Lead oxide, which is a fairly stable lead compound, is also used in ceramic glazes, rubber vulcanisation agents, plastic stabilisers, and some paints.

Some types of bullets are still made from lead alloys, and lead tin solder is still reasonably common in electronics and other applications not intended to carry water for human consumption.

If you've ever had an x-ray, chances are both you and the attending clinician wore lead shields and/or aprons to protect certain organs from exposure to radiation. However, this practice is now being called into question by a growing group of radiology organisations, who say the lead items don't really provide the protection attributed to them, and may in fact complicate the procedure 6.  Nevertheless, lead is known for its ability to block radiation, and is still used for this purpose in environments where radiation is present.

Lead And The Humble Pencil

For decades many of us assumed the lead in our pencils was made from lead but this is not actually true. Pencils as we know them – that solid tube of soft black 'stuff' encased in wood, have always been made of graphite, and were only invented in 1795 7. However, the use of graphite in writing implements goes back to the mid 1500's after a deposit of a lead-like black mineral was discovered near Keswick in England. This similarity in appearance to lead led to the mineral being called 'black lead' and so began the assumptions about the lead in 'lead' pencils. The fact that the solid mineral core in pencils was also called 'the lead' due to what it was thought to be made of, has compounded the misconception.

Whilst it may not have been used in pencils, lead was definitely used in other types of writing implements in ancient and not so ancient times! Notably the Romans developed a lead stylus that they used to 'write' on clay tablets. The styluses even had their own 'eraser' in the shape of a flattened tip that could be used to smooth over mistakes in the clay.
When writing on sheets of papyrus became the norm, the styluses evolved to write on that medium – the lead left a faint marking on the papyrus. It's thought that the lead stylus was likely preferred over reed pens because they didn't need ink.

During the Middle Ages, lead and silver styluses were used to score straight lines in the parchment to keep the lines of text straight, and to mark out illustrations that would later be painted. The text itself was written using the now popular ink and brush writing implements.

Lead Production

Many lead products like lead-acid batteries and lead sheets are recyclable, and over half of new lead products are in fact made from recycled lead. This makes lead one of the highest recycled materials used today.

Even so, lead mining is still big business with China, Australia, and the USA topping the tonnage production list. For recycled lead, the USA, China and Germany respectively are the top producers. The largest lead producer by far, accounting for over half of all lead production (mined and recycled) is China.

Galena remains the most commonly mined lead ore, not the least because it contains economically viable quantities of silver and zinc as well. Other lead ores being mined are cerussite and anglesite.


References:​

  1. Lake Sediments Record Prehistoric Lead Pollution Related to Early Copper Production in North America
  2. Lead from Roman mines pollutes ancient Alpine ice
  3. Just two countries away from global elimination of lead in petrol
  4. Storing Wine in Crystal Decanters May Pose Lead Hazard. Lawrence K. Altman. New York Times. 19 February 1991
  5. Graziano, P (1991). "Lead exposure from lead crystal". The Lancet. 337 (8734): 141–2. doi:10.1016/0140-6736(91)90803-W. PMID 1670790. S2CID 11508890
  6. No Shield From X-Rays: How Science Is Rethinking Lead Aprons
  7. The Surprising History of the Pencil – Brain Pickings
​Lead Poisoning – An Ancient Problem That Is Still...
​The Metals Of Antiquity – Tin

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