A ballpoint pen contains a metal ball housed in a socket that dispenses ink onto paper as the ball turns. A roller point pen, or roller ball pen, also uses a rolling ball but utilizes free-flowing ink for smoother writing.
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Ballpoint pens hit the U.S. market in 1945 and were an instant success. Roller point pens were introduced after the 1950s.
Low cost, availability and reliability make the ballpoint pen a popular choice. Various colors and styles help sales of the roller point pen, despite its higher cost.
Designed to dry quickly on paper, ballpoint pens use a thicker, oil-based ink that allows a slower flow of ink to the paper and is absorbed quickly. Roller point pens use a water-based ink that absorbs on paper faster than ballpoint ink.
To understand how the roller point pen works, Jeff Elder of the Charlotte Observer newspaper suggests looking at roll-on antiperspirant: “Works the same way: The ball is in a socket that allows it to roll, constantly picking up the liquid behind it.”
More than 146 million BIC Cristal ballpoint pens are sold each year in the United States, according to BIC Consumer Products USA. The ball at the tip of a roller point pen can roll up to 2,500 rolls per minute, according to Leighton Davies-Smith of Newell Rubbermaid.