Which Scottish chemist invented the waterproof fabric used in Mackintosh coats?

The Scottish chemist who invented the waterproof fabric used in Mackintosh coats was Charles Macintosh.

In the early 1820s, Macintosh developed a fabric made by sandwiching a layer of natural rubber dissolved in naphtha between two layers of cloth. He patented the material in 1824. The naphtha was produced from coal tar, linking the invention to the chemical industries developing during the Industrial Revolution.

The resulting garment became known as a Macintosh or Mackintosh, with the spelling containing a k eventually becoming common. Early coats were genuinely waterproof but had drawbacks: they could smell strongly, feel stiff, and deteriorate or soften in hot conditions. Charles Macintosh later worked with rubber manufacturer Thomas Hancock, whose improvements helped make the material more practical.

The inventor is often confused with James Syme, who published work on dissolving rubber in a coal-tar solvent. However, Macintosh's distinctive contribution was applying the rubber solution between layers of fabric to create a waterproof textile. The modern raincoat name preserves his surname.