HISTORY18 - Wine Containers, Sealants, and Punts

I started out writing an opinion piece about how screwcaps are better than corks for sealing wine bottles, and how punts (indentations) on the bottom of wine bottles are unnecessary.  I began researching wine container sealants and punts and quickly was overwhelmed with history that I didn’t know much about.  So, this article became a history article; I’ll leave conclusions and opinions to the reader.

The first known evidence of wine is from ca. 6,000 BC in the Middle East, but evidence of so-called “fermented grape drinks” dates back to at least 9,000 BC in northern China.

Wine Containers and Sealants

Since the discovery of fermentation, people have enjoyed drinking wine and have looked for ways to keep it fresh, tasty, and portable. 

Wineskins, containers made from animal hide or bladders, are some of the earliest known vessels for storing and moving wine.  It is difficult to say when they originated, since animal hides degrade over time.  Written references go back to Homer’s Odyssey (8^th century BC) and continue through Shakespeare’s plays.

But more permanent storage for higher volumes of wine was also necessary and came in the form of pottery.  From as early as 6,000 BC, in Georgia, east of the Black Sea, large earthenware jars were utilized both above aground for high volume transport as well as partially buried for preservation.  For millennia, these beeswax-coated earthenware jars, called kvevris, were used to ferment, store, and transport wine.  Once the period of primary fermentation was over, the containers were covered with a large stone to create an airtight seal.  To make the containers even more airtight, the Romans applied an inner and outer coating of heated resin.

Earthenware kvevris were used to ferment, store, and transport wine from 6,000 BC to Greek and Roman times.

The ancient world’s standardized way to store and transport wine was in clay vessels called amphorae, that came in may sizes, for bulk transport and individual use, shaped like long, tapered vases, with a pair of handles at the top.   The long, slim neck reduced the surface area exposed to oxygen.  For transport, large amphorae could be strung together by a rope through the handles and carried on ships like a bunch of grapes.  These wax-lined ceramic containers, invented by the Egyptians, were gradually adopted by nearly all drinking/producing civilizations throughout the Mediterranean and Mesopotamian regions – the primary way of storing and transporting wine throughout the known world, from the days of the Greeks until the end of the Roman Empire.

Amphorae were used to store and transport wine from the days of the Greeks to the end of the Roman Empire.

Sealing an amphora was a challenge and the solutions varied over time.  Amphorae were originally sealed with a clay stopper, but these stoppers allowed a good bit of oxygen to enter the vessel, causing early degradation (by oxidation) of the contents.  The Egyptians used materials such as leaves and reeds as seals, both covered in semi-permanent wet clay.  Later the Greeks and Romans experimented with rags, wax, and cork.  Resin adhesives were prized by the Romans for the varied flavors they added to the wine.

As the Roman empire expanded, they countered Gauls who transported beer in wooden barrels - invented by the Celts.  When the Romans realized that wooden barrels, bound together with metal hoops, were stronger, lighter, and more portable than amphorae (they could be rolled and stacked), barrels for wine became the rage, and their use spread throughout the world, dominating the wine storage and transport world for centuries, into the 20^th century. 

The first glass bottles were produced in southeast Asia around 100 BC, and in the Roman Empire around 1 AD.   The trouble was with the method of manufacture.  Glass at the time was hand blown, and bottles therefore varied wildly in size.  Because early glass bottles were so breakable, hand-blown glass couldn’t be made to a standard measure, using bottles as a primary mechanism for storing wine just wasn’t practical.  Glass bottles were used primarily to get the wine from the barrel to the drinking cup.

It wasn’t until the 17^th century that improvements in glass making provided thicker, harder-to-break, bottles than previously.  It became safe to store and transport wine in glass bottles.  In the early 19^th century, professionally-made glass molds of iron or bronze were used to blow glass wine bottles with an almost uniform shape.  The invention of the automatic glass bottle blowing machine in 1880 industrialized the process of making standard-sized bottles.  Early wine bottles had fat bottoms and short necks.  Over time, the neck grew in length, and the bottom slimmed, and by the early 1800s, we see shapes that resemble modern wine bottles.

Glass wine bottle evolution.

For a while, glass stoppers were used to seal wine bottles, but they didn’t keep out oxygen very well because it was difficult to make a tight fit with two pieces of hard glass.  Also, once sealed, it was sometimes difficult to remove glass stoppers from the bottle.

Corks became the wine bottle sealer of choice because it was quickly discovered that compressible corks were capable of keeping enough oxygen out of the bottle to vastly extend the practical life of most wines, thus allowing wines to age and evolve slowly over time in long-term storage. 

An easy-to-use corkscrew, to remove corks from wine bottles, was created for the wine lover or tavern owner in the late 1700s.

Cork comes from the bark of a type of oak tree known as Quercus suber. The trees are not properly viable for cork production until they are between 15 to 25 years of age.  Once grown, the bark is stripped from the trees.  This harvesting process does not injure the trees and the bark regrows.  It can take a decade before a cork tree is ready for another harvest. Consequently, cork harvesting is a long-term process. Trees are carefully marked and accounted for.  Each tree is an investment for the future of the companies and farmers that tend to them.  Italy, France, Portugal, Spain, and North Africa hold the majority of the world’s cork tree forests.

In 1889 Dan Rylands of Barnsley in the UK invented the screwcap for bottle and jar closures, but it wasn’t until the late 1960s and early 1970s that a French Company, Le Bouchage Mecanique, developed effective screwcaps for wine bottles.  Screwcaps consist of a metal cap with a liner inside the top of the cap that attaches to the bottle lip for its seal.  Screwcaps provided a tighter seal than corks, allowing virtually no air into the wine after bottling.  The practice of using aluminum screwcaps to seal wine bottles began in earnest in Australia and New Zealand in the 1970s and has expanded worldwide since then.  But, since their introduction, screwcaps have been fighting the stigma of being associated with lesser quality wines. 

Alternatives to wooden barrels and wine bottles for transport began to be appear in the 1960s.  Giant plastic bladders were developed to transport wine in large quantities, taking advantage of the weight-volume advantage over heavy wine barrels and cases of wine bottles.  Other transport vessels that have come into use are metal tanks and aluminum kegs.

Also, in the 1960s, alternatives to glass wine bottles for packaging wine for consumers were introduced.  The first of these was the invention of a plastic bladder in a cardboard box - the birth of so-called box wines.  Other packaging alternatives were developed for greater consumer convenience - by providing serving sizes appropriate to the moment or event, and greater durability - providing packaging that doesn’t shatter (easily), and can be served in places where glass is not permitted. Other alternatives to glass wine bottles include aluminum cans, aluminum bottles, plastic bottles, flexible plastic pouches, and single-serving plastic wine glasses.

Common wisdom in the wine industry is that 70-90% of all wine bought is enjoyed within 24 hours of being purchased.

Glass wine vessel makers have responded with alternative size (larger and smaller) wine bottles, crown cap (like beer) closed bottles, and even “test tubes,” small glass tubes of wine samples.

Glass bottles are still the preferred wine container, as they have excellent oxygen barrier properties and can protect wine nearly indefinitely.  Glass continues to dominate the wine container market, accounting for about 85% of the global total in 2015.

According to an article in “The Drinks Business,” a British trade website, out of 18 billion bottles of wine marketed worldwide in 2016, 11.5 billion, or 64 percent, were sealed by cork, with 4.5 billion, or 25 percent, under screwcap.  Plastic corks and other closures accounted for the remaining 11 percent, but were declining in market share, while corks and screwcaps were increasing.

Corks vs Screwcaps

So, let’s take a closer look at corks and screwcaps as wine bottle sealers.

Both corks and screwcaps have proven that they can preserve wine for many years, allowing wine to age and evolve slowly over time.  Some winemakers have argued that corks permit wine to intake a little oxygen over long storage times to enhance the aging process for complex and fine red wines.  Other winemakers and wine educators say that any sustained oxygen influx after bottling is harmful (hastens oxidation of the wine), that the need for “breathing” corks is a myth that has largely been debunked, and that screwcaps that allow virtually no oxygen into the wine after bottling are the better sealant.

The biggest issue associated with corks is “corked wine,” wine that has been infected via the cork with a bacterium called TCA for short, that produces unpleasant flavors reminiscent of moldy cardboard or wet newspaper and can absolutely ruin even the most beautiful of wines.  Corked bottles of wine are a serious problem for the wine industry with as much as 5-10% of the wine undrinkable.

Another downside of corks is cost.  Corks are 2-3 times more expensive than screwcaps to produce, and the extra cost is passed down to the consumer.  Part of the comparatively high cost of cork stoppers is due to the long production process.

After harvest, the cork material has to dry on clean surfaces - takes between one to six months, depending on the moisture and density of the cork material.  Then the cork is boiled in water in large, stainless steel tanks.  Boiling cleans and sterilizes the cork, as well as softens it, allowing the cork to eventually be reshaped, into the bottle enclosures.  From there, the best quality corks are punched out of the cork bark.  Lesser quality corks are manufactured from pressed shreds of cork bark.  After being cut, the corks are once again washed, cleaned, sterilized and dried. Some corks are lightly coated in wax at this point. Next, the corks are sorted by quality, bagged, and shipped to bottlers and wineries.

Commercially corked wine bottles typically have a protective sleeve called a foil covering the top of the bottle, the purpose of which is to protect the cork from being gnawed away by rodents or infested with the cork weevil, and to serve as collar to catch small drips when pouring.  The foil also serves as a decorative element of the bottle's label.  Foils were historically made of lead, but research showed that trace amounts of toxic lead could remain on the lip of the bottle and mix with the poured wine, so lead foil wrapping was slowly phased out, and by the 1990s, most foils were made of tin, heat-shrink plastic (polyethylene, PVC), aluminum or polylaminate aluminum.

Screwcapped wine is much easier to open than wine bottles with corks.  Foil cutters and corkscrews are not required.   There are no corks broken off in the bottle, no cork particles dropped into the wine, and no more scratches trying to manipulate corkscrews on difficult corks.  And it’s easy to recap the bottle.

The one thing corks have going for them is tradition and romance - the ritual of presenting the wine, artfully extracting the cork, hearing the special popping sound, and inspecting the cork.

Punts

Not every wine bottle has a punt, but most do.  

The punt is an historical remnant from the era when wine bottles were hand-blown using a blowpipe, leaving something similar to a tiny icicle (called a punt) at the bottom of the bottle. This would hinder the bottle in standing upright, could also scratch the furniture, and might cut people handling the bottle.  So, glassmakers shaved off the icicle and pushed the punt scar up into the bottle a little.

Over the years, with the use of glass bottle molds and automatic glass-blowing machines, punts evolved to symmetrical dimples of varying sizes and depth, depending on the whim of winemakers for their particular type of wine.

Punts survive today with some so-called wine experts espousing their supposed value:

a.         Punts add to the structural integrity of the wine bottle, enabling sparkling wines like Champagne and Prosecco to withstand more pressure.  (Applies to a low percentage of wine bottles.)

b.         Punts catch sediment, allowing solids to settle evenly in a tight ring around the punt, stopping the sediment from blending back into the wine as it’s poured.  (Most modern wines contain little or no   sediment.)

c.         The punt makes it easier to hold the bottle.  (How many people have you seen hold a wine bottle with their fingers or thumb inside the punt?)

d.        The punt consumes some volume of the bottle, allowing the bottle to appear larger for the same amount of wine, which may impress the purchaser.  (Are they kidding!)

e.          Punts make your wine flash-chill quicker, because of the increased surface area at the bottom of   the bottle, allowing more ice to come into contact with it.  (Maybe we should indent our beer   bottles too.)

Today, the punt serves no general purpose at all.  It’s simply a design mark that has survived the years and become part of the folklore and tradition of wine bottling.

Note the sizable punt at the bottom of this wine bottle.

This punt extends deep into the wine bottle.