THE BASIC MATERIAL – POTTERY
Although the original object was to write about sweet wine, since many early wines were likely to have been sweet, some notes on wine in general seemed appropriate. Similarly, because wine has for so long been an important commercial item, and because the packaging directly affects the product itself, some notes on packaging also seemed appropriate.
The very earliest wine was most likely transported in skins, bladders, or some organic material. No one knows with certainty and of course these containers have not survived, but the materials would have been readily available and for carrying small amounts of wine, skin containers remained in use for many centuries – Shakespeare's Falstaff drinks from a wineskin in Henry IV. However, if one has wine to transport, one must have first made it in something, and that something was most likely a stone or earthenware vessel.
In some areas of Europe we can still see tubs for fermentation and storage cut directly into stone and some of these were even used until fairly recent times. The earliest known vessels for wine making however, are clay pots. Pottery making is one of the most ancient of human crafts and the pots would have been logical vessels for wine. Of course, this hypothesis rests on the fact that we have found ancient pottery bearing traces of wine residue. It does not rule out any other material that has not yet, and may never be, found. Nonetheless, the development of pottery seems to have been extremely important in the development of wine making.
Evidence of wine generally means that chemical analysis of the pottery has revealed the presence of some kind of fermented material. Since the wine itself is almost never found, if one finds compounds associated with fermentation and fruit on the inner walls of the container, it argues that wine may have been in the vessel. Confidence in the argument increases if there are grape seeds, wine presses, drawings, or other materials close by that suggest wine making activity. The best argument of all comes if we find similar containers of the same age that still contain wine, which sometimes happens with shipwrecks. The cold and nearly airless seabed has proven to be a wonderful place for wine storage.
The grapes that are used for wine, or at least their ancestors, are believed to have originated somewhere in the eastern part of Turkey or Armenia. This theory even has Biblical support because that area is where Noah supposedly came to rest after the great flood. As everyone knows, one of his first acts was to plant grapes. In addition, until quite recently, the earliest known connection between pottery vessels and wine was thought to have been around 6000 B.C., based on excavations in what is now Georgia, where neolithic pottery was found containing traces of wine. The location tied in nicely with the story of Noah and seemed to coincide with the spread of farming, pottery-making and wine from the Middle East to the west. However, a few years ago the story became more complicated.
Although they have a relationship spanning centuries, pottery making is assumed to be a much older human activity than wine making, The oldest pottery ever discovered was recently found in the Hunan province of China, dating to somewhere around 18,000 BC. Prior to that, Japan had been the record-holder. So the oldest known pottery is not from the Middle East, but from the Far East. Wine is closely associated with pottery, and indeed, the oldest evidence of wine making known today also comes from Northern China where archaeologists have found wine residue in pottery jars from the Neolithic village of Jiahu. Those jars have been dated to roughly 7000 B.C., which is older than anything yet found in Europe or the Middle East. Chemical testing revealed that the Chinese pots had contained a fermented beverage made from grapes, hawthorn fruit, rice, and honey. It may be that both pottery and wine making first arose in the Middle East and Caucasus. But for now, the oldest known examples of both come from China.
Regardless of where wine making originated, if wine was to be stored, early engineers faced at least three major problems in material science – they needed something impermeable, non-reactive, and relatively strong. They also needed something that could be opened and re-sealed, which created another problem because unless the seal was perfect, it compromised the impermeability of the container. Pottery was an obvious choice. It satisfied at least the first two requirements quite well and within reason, also the third.
Clay is a perfect material because it can be formed into countless shapes and sizes. Even better, when dried and fired, the resulting pottery is nearly indestructible, which is why we can still find ancient pots after thousands of years. Once grapes are fermented, the wine could be stored in large clay vessels that could be buried in the ground for temperature control, or it could be placed into smaller clay vessels for easier transportation and carrying. Leather or skin containers are not nearly as versatile. Even if put on a frame, the material likely to stretch and leak and is not viable for long term storage. Rushes or reeds can be woven and sealed with pitch, mud, or clay, but since clay alone will suffice and is not only widely available but also easier to work with, there was no need to search for other materials.
Another engineering problem, not yet satisfactorily resolved, arose when the ancients tried to fashion a closure for their containers. They had learned very early that wine had to be protected from air. A layer of olive oil could be floated on top of the wine to protect it from air, spores, insects, and flies, but if the container were transported, the wine would spill. Some type of plug had to be found. One early closure found in Egyptian sites was quite ingenious. The Egyptians closed their jars with a round piece of pottery of the same material as the jar itself, over which they placed a layer of unfired clay that they could tightly press around the lid and the jar. Being soft, that clay could also be impressed with information such as the contents of the container, the date, the name of the owner, the source of the product, etc. Wine was not the only item stored in jars, so this was a great way to ensure that you didn't come home with what you thought was a jar of wine only to find that you had actually been sold a jar of olives!
Alternative closures included oil-soaked or pitch-covered rags or wooden stoppers that could be forced into the necks of the jars and sealed with a mix of clay and resin. Of course, if the wine were moved, it would splash about in the jar and be flavored by the resin or sealing mixtures. Interestingly, the Egyptians also used cork as a stopper, although it did not become dominant until many centuries later. So the ancients learned to tolerate the flavors imparted by the closures. Or did they?
Even though fired earthenware is tough and good for holding liquids, it can still be porous. Exactly how porous depends on several things, including the temperature at which it was fired, the quality of the clay used, and the glazing, if any. The earliest pots were probably unglazed pottery, similar to the familiar terra cotta flowerpots that everyone knows. This type of pottery is not completely waterproof in that the liquid can soak into the container itself and even leak through. On the other hand, that same trait can make the container act as a simple cooling vessel. The principle is exploited today in the “wine coolers” that are sold in some houseware shops – usually a terra cotta cylinder in which you can place a bottle of wine. By allowing a bit of liquid to leech through the microscopic pores and evaporate, a container of this type can keep the contents cool. Perhaps the ancients exploited the same characteristic.
Because earthenware pots were used to store many things other than wine, including fish, oils, meats, olives, vinegar, to improve impermeability, the inside of a pot might be coated with pitch or resin. This improved impermeability but compromised the non-reactivity of the container because the coating altered the flavor of the item stored. Once again, this “flaw” might not have been a complete disadvantage, as we shall see.
Today people may be familiar with Retsina, the wine from Greece that is flavored with sap from the Aleppo pine or the Cypress trees, but sap from other trees was more commonly used. Pots from present day Iran dating back to 3000 B.C. have been been found with resin from the terebinth tree and that is more likely to have been the common sap used for coating the inside of ancient pottery. Found many places in the Middle East, the terebinth is in the sumac family, related to pistachios, cashews, mangoes and magnolias. Very well-known to the ancients, it was the original source of turpentine and in fact it is also known as the turpentine tree. It can be as large as 2 meters in diameter and can yield a great deal of sap, which in its natural state is not nearly as offensive as turpentine, and which can be used to make a pitch for coating the inside of pots.
Although pitch reduces the porosity of the containers, polyphenols from the wine can enter the pottery even through the pitch. The pitch layer will however, prevent oil from intruding into the pottery, and it is possible that Retsina came about because thrifty ancients re-used their pottery to store different items. The problem with this theory is that in experiments where pitch-coated pottery was exposed simultaneously to both oil and wine, the wine made the pitch less impermeable to the oil. That being the case, another plausible reason for pitch is that it was used for properties other than sealing. As an anti-bacterial agent, it could have been added for medicinal reasons, or to help prevent spoilage bacteria from attacking the wine. It could also have been a way to mask unpleasant or off flavors. In the ages before refrigeration, that might have been a welcome characteristic. In other words, pitch may have been used less for its effect on the container than its effect on the contents. In any event, it was commonly used in early wine storage vessels.
ANCIENT CONTAINER DESIGNBy the time pottery had reached this point, packaging technology was sufficient to allow for storage and transport and the development of extensive trade in wine. Hundreds of pottery jars have been found in various sites in Egypt. Even in their tombs, the pharaohs were buried with many pots of wine for their afterlives, often with traces of resin and herbs that had been added, either for medicinal or flavoring purposes.
As an imported item, wine was far more likely to have been consumed by the aristocracy than by the masses, who were more likely to have had some type of beer. Even so, the quantity of wine indicated by the Egyptian pottery remnants however, was more than Egypt itself was likely to have produced, which means it had to be brought from elsewhere. Tests on the pottery shows that many of the containers and wine originated somewhere other than Egypt. Most likely they were brought in by Phoenicians, who dominated the early wine trade. Phoenician shipwrecks have been found containing hundreds of jars of wine destined for foreign ports.
Conducting trade in any volume is always facilitated by standardization of measures and quantities. To meet that challenge, the engineers of the day eventually developed the container that the Greeks called an “amphora”, which was a long vase, tapered at the bottom, with two handles at the top. These could be set into the ground or into stands made specifically to hold them.
Both the Phoenicians and the Greeks were shipping nations. They transported a variety of goods far from their homes. Extremely large clay pots filled with vinegar, wine, oil, salt, or meat would be heavy to load and if broken, would result in the loss of much valuable cargo. For shipping, smaller containers made sense. On the other hand, it is less efficient and more labor-intensive to load many small containers than a few large ones, so if they were to be smaller, the containers had to be easy to load in quantity. Even with slave labor, time is money.
Thus, the unique shape of the amphora. A rope could be passed through the handles of several at once and they could then be hoisted together, resembling a bunch of grapes. The long shape and tapered bottom made them easy to fit into stands or packed into ships. When the customer received his amphora, the same shape made it easy to pour from, in the same way a bottle is easier to pour from than a round or bulbous container. It could be rested on the ground and tipped forward to pour the contents into smaller containers for consumption. The long narrow neck would both accommodate any pressure from gases in the container and would also minimize the area that was exposed to oxygen. The tapered bottom concentrated sediment and made it easy to sink the amphora into the earth for storage and cooling, and to pull it back out.
Amphorae were designed to address the logistical needs of the time and they resulted from the same reasoning that would be used to design packaging today. Economical to produce, transport, and manipulate, they are great examples of material science in the service of package design. The product was so successful it remained in use for many centuries until finally sidelined by barrels and bottles.
All amphorae are not precisely identical. Their different shapes and features correlate to where they were made, their intended contents, and their year of production. They were however, locally standardized sufficiently to be used to measure both ship capacity and vineyard yields, which were referred to in terms of potential amphorae.
Unfortunately, the word “amphora” is used to refer to many types of containers of different sizes. This can be very confusing. For example, in the ceramics world, generally, a dolium refers to a large round earthenware container, not necessarily of a fixed size. An amphora is frequently a two-handled, tapered container that held about six gallons and a cadus is a smaller version that held about half as much as an amphora. Those sizes make sense because a gallon of water or wine weighs about 8.34 pounds so that would put the weight at about 50 pounds, plus the weight of the container itself, and that is about the limit of what a single man could still comfortably manipulate. But there is no rigorous agreement on this issue and apparently never has been. Columelle and Pliny spoke of a large earthenware container called a cadus, for storing wine. Some writers refer to a cadus or an amphora interchangeably. Some writers refer to any small container as an amphora.
The amphora improved over time. While glazing had been discovered sometime around 1500 BC, and was even used for tile or bricks, most famously in Persia, glazed pots only started to appear with frequency in the first century BC. To make a glaze, some glass-forming minerals are mixed with a thin layer of clay or some other agent in which they can be suspended. The fire needs to be hot enough to melt them and if it is, the result is a water tight container. In some cases the ancients may also have been poisoning themselves. The earliest glazes were some kind of alkali, probably from ash, mixed with lime and silica. They tended to crack as they shrunk on to the pot. Adding a metal oxide helped to prevent cracking. Lead oxide produces glazes that melt at some of the lowest temperatures of any metal oxide, so it is quite useful.
There is much speculation regarding lead poisoning and the Romans. One theory implicates their pottery but on the other hand, they also used lead-lined pots to boil and concentrate the unfermented grape must. Some of the aqueducts that had been lined with lead may also have contributed, but cold water does not dissolve lead to the same degree as acidic fruit juice or wine, especially if it is boiled. Although some type of glazing had been known for many years, the Romans introduced, or re-introduced, lead oxide glazes to their pottery. Much Roman pottery was rougher and simpler than that of the Greeks and it would have been the aristocracy that used the finer glazed pottery. The issue is likely to remain unresolved but for whatever reasons, the remains of some Roman aristocracy have revealed lethal amounts of lead in their bones.
The irony is that having been used for storing and transporting wine and liquids since the dawn of time, pottery was finally perfected only just before it was replaced. Although Roman pottery is not as revered as that of the Greeks for its beauty and elegance, the Romans synthesized the learning of all who had gone before. They knew glazing and the importance of different temperatures during firing, they established efficient workshops or factories for manufacturing, and they had systems in place for accounting and shipping. After many centuries, the relationship between pottery and wine was unquestioned. That was shortly to change.