Characteristics of ballpoint pens

Compared to rollerball and fountain pens, ballpoints require more pressure to write. Ballpoints lack the free flowing supply of ink that other types have, requiring the writer to apply more pressure to the page. As a result, the ballpoint pens are less likely to leak. Their robustness makes them suitable where a firm press is required, namely for carbon copy-type forms where a layer of carbon paper transfers the writing, but not the ink, to subsequent copies. In such use other types of pens are quickly damaged beyond usability[citation needed].

Normal ballpoint pens are widely believed to be unusable in microgravity, e.g. in earth orbit, but that is reported to not actually be the case [11]. They have difficulty writing on surfaces with low adherence (such as plastics, shiny surfaces, and wet or oily surfaces)[12]. Due to the pen's reliance on gravity to coat the ball with ink, most ballpoint pens cannot be used to write upside down; however, there are special pens that do work upside-down.