Radium. It was a wonder element; everyone knew that.
Each dial-painter had her own supply. She mixed her own paint, dabbing a little radium powder into a small white crucible and adding a dash of water and a gum arabic adhesive: a combination that created a greenish-white luminous paint, which went under the name “Undark.”
Even as she watched, little puffs of it seemed to hover in the air before settling on the shoulders or hair of a dial-painter at work. To her astonishment, it made the girls themselves gleam.
“We put the brushes in our mouths,” Katherine said, quite simply. It was a technique called lip-pointing, inherited from the first girls who had worked in the industry, who came from china-painting factories.