Bosses, who were men, didn’t care. Womens labour was cheap, so much so that Graham supplemented her meagre income by painting Christmas decorations for the banks windows. The exercise reminded her of something she’d once learned: artists painted over their mistakes rather than erasing them.
And that’s what led Graham to her eureka moment. She realized she could paint over typing errors rather than erase them. She mixed white tempera paint in her kitchen blender and put it in a little bottle. Whenever she made a typo, she blotted it out with a brush, waited a few seconds for it to dry, and typed over it. Marketed as Liquid Paper, the invention became one of the bestselling office supplies of the late analogue age. In 1979 Graham sold her company to Gillette for $47.5 million.
Excerpt from: Head in the Cloud by William Poundstone