In a previous installment on PackChannel, we outlined varying industries’ uses of caps and closures. It should then come as no surprise that there is almost no limit to the varieties of caps and closures on the market today. It wasn’t always this way, though. Today, we’ll explore the beginnings of caps and closures and how these products evolved over time.
The Beginnings
For roughly 100,000 years, humans have been using containers to store food, which is generally regarded as a highly important technological development. Even though crafted with a suitable top cover, these containers were fine for solids or semi-solids, but still couldn’t securely store liquids.
As more advanced materials for storing goods were developed, covers also continued to evolve. Early sealable containers used wood pieces as plugs. Later, cork became an important primitive cap to close in liquids and would remain the primary cap tool for thousands of years.
A Desire For Change
Cork was previously fine for storing most liquids until carbonated beverages came along. Because cork has the tendency to shrink as it dries out, the building pressure from carbonation would eventually pop the cork unless it stayed constantly wet. For this reason, carbonated beverages using cork had to be laid on the side to keep the cork consistently moist and secure.
This was solved in 1859 with an early version of the flip-top closure. Using a small, insertable porcelain piece with a rubber o-ring (for sealing), flip-top closures were held in place by reverse tension wires mounted on the bottle. Many upscale or nostalgic bottling companies still employ this technique today for a throwback look on their packaging.

Though flip-top closures were fully reusable, their production was expensive necessitating a new manner of closure. William Painter achieved this in 1892 with his invention of the crown cork, which is essentially a modern bottle cap.

The simple crown cork was composed of metal, but still utilized a small amount of cork for sealing purposes where the metal contacted the glass. Modern bottle caps no longer utilize a cork piece for the seal. Though only single use, crown corks were almost immediately successful because of their cheap and basic structure. This proved to be something of a watershed moment for the development of caps and closures.

Improving On The Crown Cap
Although the industry was satisfied with metal caps, needs and desires continued to develop as cost reduction and convenience were considered. Users wanted reusability, so the screw cap was created.
In the middle of the 1950’s, plastic became available in a big way. All kinds of containers, packaging products and caps were finally able to take advantage of the flexibility and low-cost material and evolve.
Some of the changes occurred as a need for enhanced convenience, like the sports cap, which requires just an easy pull and push to open and close, or the Snap Capp, which clips directly onto the top of an aluminum can to make it resealable.
Other changes happened as a result of safety, such as the tamper resistant and tamper evident caps and closures that came about to protect people from poisoned medicines and other products. Also designed for safety are childproof caps, which prevent children from being able to open medicines, chemicals and other dangerous products.
  
The Present
Humanity has made amazing developments with caps and closures in some thousands of years, but especially in the last century and a half.
Beyond the practical developments for caps and closures, useful technologies, like injection molding, allow manufacturers to create infinite varieties of shapes, colors, and styles, all depending on a customer’s needs.
Though many changes have occurred since the beginning of container usage, many things have indeed stayed the same. Wine bottles with screw tops can be easily found next to cork closures, and for many different types of carbonated beverages, crown corks (vis á vis bottle caps) are still quite the norm.
When choosing the appropriate type of cap or closure for your product, it’s always best to consult your customers’ preferences. For example, despite the many advantages of plastic, sometimes its flexibility isn’t always appropriate.
So, next time you open a pill jar, pop a champagne cork, or remove a bottle cap, consider how it got there and take a moment to wonder what will come next.