What’s the connection between this cache (don’t worry, it’s safe) ,a tasty tropical fruit, a nasty skin rash and Japanese furniture? The answer is urushiol – an oily mixture of organic chemicals found in the sap and other parts of plants such as mangoes, poison ivy and the urushi – or lacquer – tree.
For more than 6000 years, Japanese craftspeople and furniture-makers – as well as those in China and Korea – have used the sap of the urushi tree as a glue and varnish. This urushiol mixture is tapped off from the trunks of the trees. Natural latex is collected from rubber trees in a similar way. Painted on in multiple thin layers, urushiol oxidises and polymerises in conditions of high heat and humidity, creating a shining, solid coating.
Finally, there’s the mango connection. Mangoes belong to the same plant family as poison ivy.