What do you think of when someone says resin? Images of sticky, gummy sap-like substances instantly jump to mind, and most people consider all these plant products to be resins. Not all these sappy liquids are resins, however.
Resins are plant products that are not soluble in water, harden when exposed to air, and are typically aromatic. They have been valued by humans for tens of thousands of years across cultures and continents.
Amber
European amber trade first began in the Stone Age, yet amber had been used ornamentally for hundreds of years before that. The best known amber deposit is from the Baltic Sea in north-central and Eastern Europe. From there, amber trade routes went to the Black Sea and the Mediterranean Sea and beyond.
Amber artifacts have been found in China (from Myanmar deposits) and Central America. Many cultures valued amber as religiously significant, due to its warm tones and ability to preserve life such as insects and plant parts. Other cultures used it to bargain for metal and necessities. Today, amber is still valued for its aesthetic beauty.
Incense
Traditionally, incense was derived from plant resins, commonly from frankincense and myrrh trees. Resin is tapped from the tree and allowed to harden. When it is burned, the hardened resin releases aromatic smoke.
Incense was a valuable commodity. Trade routes began from the southern coast of Arabia to the Mediterranean and Mesopotamia regions, beginning c. 1000 BCE and ending shortly before 500 CE. Both the Maya and the Aztec used resin from the copal tree as incense. Today, incense is made of other plant materials in addition to resin, such as leaves, bark, seeds, fruits, roots, and rhizomes.
Resin in Shipbuilding
Ship builders have used the liquid form of resin for thousands of years. It was used to waterproof rope and tarps, and was made into tar or pitch to seal the seams of wooden ships. The British Empire used resin for its navy, originally buying it from the Baltic region. As sources of resin disappeared along the east coast, manufacturers looked elsewhere in America for resin sources.
Turpentine and Rosin
Resin was also used to make turpentine and rosin. Turpentine was traditionally used in paints, but is now used in the chemical industry as a base to produce solvents, cleaners, fragrances, dry cleaning, and insecticides. It is also used in artificial flavors such as lemon, peppermint, and nutmeg, as well as cosmetics. Rosin was discarded as a waste product until after the Civil War. It was used then as laundry soap but now as a variety of unrelated industrial products, such as adhesives, printing inks, and chewing gum.
Varnish and Lacquer
Varnish is plant resin combined with a solvent and drying oil (also derived from plants) to make it easier to apply to surfaces. It is commonly used for wood finishing and other crafts to provide protection and a glossy finish. Natural lacquer is simply liquid resin. Today, lacquer is a mixture of resin and quick-drying solvents.