Cork saw its most significant increase in use in the late 19th and early 20th centuries. At the time, almost every home contained some form of cork. Cork residential uses ranged from seals and gaskets to soda bottles, corkboards, and more! Outside of the home, cork had an even more outsized role in shaping the modern world through its industrial and military uses.
During the early 20th century, cork emerged as the material of choice for sealing applications. Its ability to create a secure seal and its practical and cost-effective nature in a pre-plastic era made it the preferred option. Cork's role in manufacturing, particularly as gaskets in machinery producing a wide range of goods from automobiles to children's toys, was significant. Its importance was further highlighted during the world wars, especially the Second World War when the Allied Forces ramped up industrial production. Cork's intrinsic properties and practicality made it indispensable for war materials, from canteen stoppers to shipbuilding and munitions. Using cork gaskets and sealers facilitated the secure fitting of imperfect parts, improving production speed.
Vintage bottle “crowns” with cork interiors which were frequently used on soda bottles in the 1900s
In addition to its sealing properties, cork's insulating capabilities were crucial for the war effort. Starting from World War I, cork was used inside the pressurized hulls of submarines, serving a dual purpose. It effectively stabilized the extreme temperatures within the vessel and reduced condensation, enhancing the crew's comfort and minimizing the risk of electrical shorts and grounds. Because of its exceptional insulative properties, cork was also used as an insulator in non-refrigerated cold storage areas on land and naval vessels.
Cork's natural ability to float was also utilized in the war effort. There are several reports of a cork being used on netting to allow for a sizeable, easy-to-hold flotation device in the event of sinking. However, the most intriguing use of cork may be the British Navy's Q-Ships. These Q-Ships were "secret service" ships manned by Royal Navy Sailors in disguise like their ships. These ships were made to look like cargo ships, complete with deck cargo, but the cargo was hiding a deadly surprise - deck guns and ammunition. These decoy ships aimed to lure German U-boats out into the open by convincing them they had discovered an unescorted cargo ship. To help protect against torpedo hits, the cargo hold of the Q-Ships was filled with buoyant material, frequently cork, for added buoyancy.
The need for cork was so great that efforts were made in the United States to plant a domestic cork oak forest. The remnants of this endeavor can still be seen in cork trees across the United States. After the end of the Second World War and with the rise of plastics, there was a reduction in domestic production of cork goods, which was of great concern to the War Department and other National-Security focused branches. Cork's intriguing properties made it a prime material for the new frontier - space, making ready access to the material all the more critical.