Innovations and trends that shaped your ancestors' lives. In this issue: adhesives.
When our ancestors needed to glue together broken shards of a pot or even do something as simple as connecting two pieces of paper, they relied on sticky substances from nature. Tar, beeswax, tree sap, egg whites, milk, decomposed animals, cheese and even blood were used for what turns out to be an essential human activity: sticking stuff together.
That all changed 100 years ago with the invention of phenol formaldehyde adhesives for plywood. Though little-heralded at the time, this breakthrough launched the modern adhesives age (as well as the plastics age—phenol formaldehyde would be put to use in Bakelite, the first synthetic plastic). In 1940, 95 percent of the raw materials in adhesives were still derived from natural sources. But by the 1980s, that figure had dropped to 35 percent as chemists custom-blended adhesives out of synthetic polymers.