What is ink?
Ink according to the Oxford Dictionary is: “a colored fluid used for writing, drawing, printing, or duplicating.” According to Wikipedia: “Ink is a liquid or paste that contains pigments and/or dyes and is used to color a surface to produce an image, text, or design.” Britannica Concise Encyclopedia defines it as a “Fluid or paste of various colors (usually black or dark blue) used for writing and printing, composed of a pigment or dye in a liquid vehicle (solvent).” No matter where you look for a definition, all of them have something in common; the purpose of ink is to deliver a visual image. Inks are found in almost every aspect of human activity.
The first inks used were made of fruit or vegetables juices; blood from some types of animals and bark from trees. The first man made inks were made from animal or vegetable charcoal mixed with glue and it appeared in Egypt about 4,500 years ago. Older style writing inks, such as in fountain pens, use a fluid water-based dye system. But in the 1950s, when ballpoint pens became fashionable, the writing ink industry shifted to paste like oil-based dye systems. The thick consistency allows capillary action to keep the ink flowing well, and the inks generally are no smearing and quicker drying than water-based systems. Dyes tend to be preferred over pigments for writing inks because pigments can't be dispersed minutely enough and tend to clog the pen tip. Water-based dye or pigment systems are still used for markers, highlighters and rollerball pens. A few pen manufacturers, such as Bic (which sells about 3 million pens per day) make their own ink, but most pen manufacturers buy their ink.
There are various types of inks available today, all used for different purposes in the printing market. Newspapers, magazines, photo and book publishers are just a few examples of the paper base industries that use inks in a daily basis. Even the governments use ink to print money. But there are a lot more industries that depend on inks to deliver a message; apparel, beverage and paint industries are some good examples. In today’s developed nations, most residences and businesses have a printing capability and having an inkjet printer is very common in most countries. At home ink is used to print homework, reports, bills or just to print some drawings to keep the kids busy doing some coloring (I’m guilty as charged).
Today's inks are divided into two classes: printing inks and writing inks. Printing inks are further broken down into two subclasses: ink for conventional printing, and ink for digital nonimpact printing, which includes ink-jet and electrophotographic technologies. Inks also contain additives such as waxes, lubricants, surfactants, and drying agents to aid printing and to impart any desired special characteristics. An average size magazine issue of 80 pages requires a total of only about 68 gal of ink to print just more than 150,000 copies. The advent of personal computers, personal electronics, and the Internet may one day replace libraries full of printed books and periodicals with electronic products. Look how many e-books are already in use. But the great paperless society hasn't fully shown itself yet, many industries still rely on paper. And as long as there's paper, then there must be ink.