when the piston of fountain pen with a nib is dipped into ink and the air is released by pressing it the ink fills in the pen why
Answers
Their are several types of ink reservoirs currently built into fountain pens. The most elaborate tend to be on Italian models. They might require you to draw a piston out far from the backside of the pen, and then fill the pen on the down stroke (assuming the nib and section were immersed in ink)! They might require you to turn a knob several times in one direction without turning it backwards. That is but the tip of the iceberg.
At any rate, the most common types of filling mechanisms at the moment are the ink cartridge and the piston fill. The former usually involves removing the barrel from the section and fingergrip, then pressing a fresh cartridge over a sharpened pipe that lets the ink flow to the tip. To start things up, you wrap a paper towel or hanky (NOT a facial tissue!) around the tip and give the pen one or two vigorous shakes to drive the ink to the nib.
Modern piston fills were patented by Gunther Wagner Pelikan Werke many years ago. There are several varieties. Most commonly, they plug into the pen just like a cartridge. A long turnable knob protrudes from the back. Twisted one way, it lowers a piston down the length of the reservoir. Twisted the other, the piston retracts. To use, twist the knob until the piston is all the way down. Completely immerse the nib until the end of the fingergrip is barely submerged, then turn the knob in the other direction to draw in the ink. Wipe away the excess ink, and the pen is ready to write. On some pens, the piston is operated by a slide rather than a twist. Going even further, many really good pens have the piston built in and have no option for a cartridge. They tend to hold much more ink than a cartridge pen. The knob works just as I’ve already described, except that the first twist elevates the knob a bit so that you can tell that the piston is turned down. The pen may or may not have a transparent area to see if the reservoir is full.
The reason for not using a facial tissue to wipe a pen nib is because it contains tiny glass fibers. Also, a piston is a convenient (if a little slow) way to rinse your pen out with water; you simply draw it back and forth until the water comes out clear.
I prefer not to use cartridges myself. They tend to be a little more expensive for the amount of ink you get, and they have limited color variety. In fact, the only time I use them is on trips, where they’re easier to tote than an ink bottle. Finally, drawing ink back and forth with the converter appears to keep the pen cleaner, even if you don’t rinse it frequently.