Avocados have become popular in restaurants and homes because, in food-science terms, they act as a "covalent bond" with other ingredients.

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Locklin and his colleagues sprayed the substance onto materials and exposed them to ultraviolet light, which causes a covalent bond with the host material.

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They performed this trick, as they explain in the journal Langmuir, using a substance called phenyl azido, which readily forms covalent bonds with its neighbours when exposed to ultraviolet light.

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Accordingly, Dr Lin and his colleagues tried to build up covalent bonds between the layers of a water-repellent, or hydrophobic, material called cellulose acetate butyrate, which is used to make water-resistant fabrics.

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