How Does a Ballpoint Pen Work?
Inside a ballpoint pen is a little plastic or metal tube that holds a supply of ink. At the tip of the pen is a tiny ball which fits snugly in a holder. The ball takes the place of the point that is found on a fountain pen. Because its tip is actually a little ball, this pen is called a ballpoint.
As you write, the ink in the tube wets the ball and the ball rolls ink onto the paper. The ball is kept in place — between the ink reservoir and the paper — by a socket; and while it is in tight, it still has enough room to roll around as you write.
As the pen moves across the paper, the ball turns and gravity forces the ink down the reservoir and onto the ball, where it is transferred onto the paper. It’s this rolling mechanism that allows the ink to flow onto the top of the ball and roll onto the paper you’re writing on, while at the same time sealing the ink from the air so it does not dry in the reservoir.
Ballpoint ink is not the flowing kind that is used in fountain pens, but a much thicker type. The color is so strong that the ink can be rolled out in a very thin line and still make a good mark.