It also results in a solid and uninterrupted line, since the diffusion of the ink through the paper fills small gaps that might otherwise be left by the ball point. Compared to ballpoint pens, which dispense a smaller amount of more viscous ink, the writing by a rollerball pen takes longer to dry on the page and can seep through thin paper such as to become visible on the opposite side. When the tip of a rollerball pen is held against paper, ink leaves the tip continually by capillary action in much the same way as would occur with a fountain pen.