How does a fountain pen only consume the ink it needs and does not leak?
In: Engineering
Surface tension. The cohesion of the ink to itself and the outside edges of its tip keep it in place. Like how small drops of water will stick to your fingers. But because ink is thicker, it can stay in something like a pen tip until it finds something more binding, like paper.
It’s the same as putting you finger on a Straw to get the water out you glass I’m sure
Hmm… I will need to look that up lol
If you look at the ball in a microscope, it has little pores in it that hold a tiny amount of ink. The clearance between the ball and its holder is small enough that the ink doesn’t leak through the gap. That little trick works because all liquids have a quality known as viscosity. You know that honey is very viscous: when you try to pour honey it just oozes slowly. Well, it turns out that all liquids have some amount of viscosity, even ones we think of as not “viscous” like honey. Ballpoint ink is specifically formulated to be just viscous enough to not leak through the gap between the ball and the housing, but able to flow into the little holes in the ball. The ink also acts as a lubricant between the ball and the housing, allowing the ball to spin. If the ink dries out, the ball doesn’t turn, which is why you sometimes have to scrub the ball around a bit to get an old pen to work.
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