Think ink!

If you think ink is no big deal, think about this: How would you like to carry a backpack full of stone books to school every day? Before ink was invented, people wrote pretty "heavy" messages to each other. They carved pictures and letters into stone or pressed them into wet clay.

The earliest known writing consists of drawings carved into cave walls. These showed important events such as a hunting trip or planting season. Then, thousands of years ago, the Greeks began to use a writing stylus, made of bone, metal, or ivory, to scratch marks into tablets coated with wax. Writing was still a lot of work, but at least you could move it from place to place, which you couldn't do with cave walls.

About 5,000 years ago, the Chinese began using ink for writing. The ink was a mixture of soot from pine smoke and lamp oil, thickened with gelatin from animal skins and musk. It was first used for blacking the raised surfaces of pictures or letters carved into stone. Later it was used to form the letters themselves, without carving them in stone first. A Chinese philosopher, Tien-Lcheu, who lived around 2700 BC, developed a form of ink that was in common use by 1200 BC.

Other cultures developed inks from berries, plants, and minerals available in their areas. These inks were different colors, which could indicate different meanings. In ancient Egypt, red ink was used for people's titles and to write the names of the gods.

As inks improved, paper was developed and improved. Early Egyptians, Romans, Greeks, and Hebrews soon were using paper made from the papyrus plant and parchment made from animal skins. The earliest known papyrus writing is the Egyptian "Prisse Papyrus," which dates back to 2000 BC.

Ink consists of a colorant and a liquid or paste to carry the color and bind it to the paper. Crushed berries make a lasting color, as do bark and certain plants. Some minerals can be ground to powder for color. Carbon from soot makes a deep black ink.

Around AD 300 the Chinese developed a solid ink that could be stored as a stick or cake. When you wanted to do some writing, you shaved some ink off the stick and mixed it with water. This type of ink is still used today through East Asia. In the United States, these sticks are often called Chinese ink or Japanese ink. Black ink made from carbon is often called India ink in the US, even though it was developed in China.

About 1,600 years ago, a popular ink recipe was created. The recipe was used for centuries. Iron "salts," such as ferrous sulfate (made by treating iron with sulfuric acid), was mixed with tannin from gallnuts (they grow on trees) and a thickener. When first put to paper, this ink is bluish-black. Over time it fades to a dull brown.

Scribes in medieval Europe (about AD 800 to 1500) wrote on sheepskin parchment. One 12th-century ink recipe called for hawthorn branches to be cut in the spring and left to dry. Then the bark was pounded from the branches and soaked in water for eight days. The water was boiled until it thickened and turned black. Wine was added during boiling. The ink was poured into special bags and hung in the sun. Once dried, the mixture was mixed with wine and iron salt over a fire to make the final ink.

Writing with ink requires using a pen or brush. The earliest pens were probably pointed sticks or the like dipped into ink. People gradually learned how to make a pen that could hold more ink so it didn't have to be dipped so often. They would sharpen the point of a bird's feather and cut a shallow trough to hold the ink. The Romans made pens from the stems of marsh grasses, including bamboo. The tubelike stems could hold a small amount of ink, and the end could be cut to a point to make a finer line. Squeezing the reed forced ink in the stem to flow to the nib. It was the earliest kind of fountain pen, perhaps.

For more than 1,000 years, beginning around AD 700, the quill pen was the favored writing instrument. The finest ones were (and still are) made from one of the five flight feathers from the left wing of a domesticated goose. Swan feathers were more expensive because they were harder to get. Crow feathers were good for making fine lines. Quill pens must be resharpened often, using a special knife - a pen knife, in fact. A quill pen lasted about a week.

Inventors tried to make more durable pens that could hold more ink. The oldest known example of a pen with an ink reservoir (an early fountain pen) was created by Frenchman M. Bion about 1702. Early fountain pens were prone to spills and breakdowns.

An American 19th-century insurance salesman named Lewis Waterman became determined to improve the fountain pen when a leaky pen ruined an important sales contract. He added an air hole in the nib and put grooves inside the mechanism that moved the ink to the point. He patented the pen in 1884.

19th-century American inventor Thomas Edison also focused some of his creative energy on writing instruments. He developed an electric pen, an early example of a copy machine. At that time, if people wanted a copy of a document, they had to recopy it by hand. Stencil copying was also an option. First a drawing or manuscript was made by making tiny pinpricks through a piece of paper. Ink was pressed through the holes in the paper onto a paper underneath to make an image. Several copies could be made from one stencil.

Edison's electric pen had a battery-powered motor to move a sharp stylus up and down through a hollow tube. A writer could guide the pen to form letters for a stencil at high speed. About 60,000 electric pens were sold, but other stencilmaking technologies evolved that were less expensive. The typewriter - and the carbon copy - made stencils obsolete in the 20th century.

Ink, on the other hand, is far from obsolete. As mechanical copying and printing became more popular, new inks were developed. A special green ink was invented in 1857 by American chemist Thomas Sterry Hunt. It resisted attack by acids, bases, and other chemicals. It couldn't be reproduced accurately in a photograph - and so was used to print US currency.

Printing ink is greasier than ink used for writing. Printer's inks are designed to work with specific kinds of printing equipment to form the clearest image without accumulating in the machinery.

Now you can walk in a store and choose from a rainbow of inks in pens of all shapes and sizes. They may not improve the quality of what you write, but they do make it easy and fun.

• To learn how to make your own "invisible ink," visit chemistry.about.com.