Which ingredients are used for making ink for pen? What is the function of hole in the middle of the nib of a fountain pen?

Ink is made from two main constituents, viz, colour pigment and liquid which can carry colour pigment via the nib. These constituents of ink are made from various substances. In some countries manufacturers use tincture of a wood known as logwood (such logwood trees grow profusely in Central America, Mexico and the West Indies). Natural colour of logwood is deep red but after long exposure to open air this wood automatically becomes blue-black. The ii pigment of this colour for makig ink is extracted through distillation. It is essential that colour of ink remains fast on paper and does not become blurred. 

In order to infuse this property in ink manufacturers besides mixint43.5 grams pigment in each litre of distilled water add 5.0 gramsAolic acid, 7.5 grams ferrous sulphate and 1.0 gram tartaric acid. The ink of ball pen has to be viscous rather than liquid and should not evaporate like liquid. Therefore, a colourless viscous substance named ethylene glycol is used in manufacture of ball pen ink instead of distilled water. The line drawn by tiny bearing of ball pen is very thin. It does not spread automatically on paper so it does not become bold. To overcome this drawback about 20 times more pigment is used in making ball pen ink as compared with the ink for pen. The reason for a hole in the nib of a fountain pen is quite elementary and can be gauged with some focused reasoning. Just as tiny ball bearing performs basic work of writing in case of ball pen, split nib performs the work of writing by the pen. (See the diagram below). As the nib is placed on paper some light pressure that comes to be applied on it slightly widens the split of nib. This phenomenon brings internally stored ink via serrated feeders on to the split of nib through capillary action—and thus writing on paper commences. It is obvious that as the ink comes out it creates vacuum inside pen. The hole on the nib is the tiny window which lets in air to fill the vacuum. How can writing proceed unless there is equilibrium between internal and external atmospheric pressures?