Question

the ink get sucked in the
fountain pen because of



​

Answer 1

Answer:

the ink in a pen is viscous and slow-moving because of the nature of the dynamics in the design. Therefore, you have no obstacle above the ink…but there is the ink ‘plug’ that offers resistance when you blow into the tube.

Answer 2

It is easier for a fluid to flow through a tube that has a narrow opening at the intake end and a wide opening at the outtake end than it is to flow in the opposite direction (from wide to narrow).

The fountain pen has a device upstream from the nib called a collector. Its purpose is to prevent ink from running out of the ink tank or cartridge and flooding the nib. It provides a slow, controlled flow of ink. The reason that it is called a collector is that it acts as a sort of holding tank right behind the nib (actually, the pen point; the whole assembly in front of the section is the nib). It does that as part of its job as a flow control device.

So how does this help us to understand the difference in ink flow rates going into the pen versus coming out of the pen?

The method of filling the ink reservoir from a bottle involves drawing ink up into the internal reservoir or ink sac through the nib using some suction-inducing mechanism (which varies with different brands). The ink is first drawn into the feed (the external extension of the collector) and then into the collector itself. Once it has saturated this structure it flows directly into the reservoir.

There is no (or much less) restriction of ink flow on the end of the collector that faces the ink reservoir, which only makes sense. You want the ink to flow freely into the reservoir as you are filling the pen, so there is little to impede it at that end. All of the flow control is at the downstream end which at the moment is flooded because it is totally immersed in a bottle of ink. So the reservoir inside the pen fills rapidly when ink is sucked into it, which is exactly what you want to have happen.

But as described earlier, the flow of ink back out of the pen is restricted by the action of the collector and the feed. Again, this is exactly what you want to see happen. You want the ink to be fed down to the point in a nice, even and very controlled rate as you write.

So the answer to the question is: the pen has that observed differential flow rate by design, because it is necessary for it to be able to operate correctly. The addition of controlled ink flow without skips (too little flow) or blobs (too much flow) is what finally made a workable fountain pen successful after centuries of failed efforts. A device or feature inside the pen is what is responsible for this difference in ink flow rate between uptake and release and it is an essential part of the pen.