Question

Explain the mechanism of a reffil pen..

Answer 1

When you put the nib on paper and drag it along, the ink is pulled down a slit in the center of the nib, and down the feed, by capillary action. That means it's pulled partly by the adhesive forces between the ink and its container (the slit in the nib and the three little channels in the feed) and partly by the cohesive forces between every ink molecule and the ones following on behind it). More ink then flows down the feed from the reservoir to take its place. Think of it this way if you prefer: as each ink molecule hits the paper, it drags on the molecules that are just inside the nib, tugging on them as though they were linked by a chain, and eventually pulling ink from the feed and the reservoir. Air enters the pen at the same time through the slit in the nib, and moves in the opposite direction, gradually filling up the reservoir as it empties of ink.