Craig London, age 10 of Oakland, Calif, for his question:
What exactly is ink?
Even the government is interested in this fluid which we use for writing. A scrap of paper is stolen or lost, this may lead to a tale of trouble and adventure. For the bit of paper is a signed document: The signature makes it important. A signature is a person's name written by himself. The law accepts that document as proof that he read the paper and agreed to it produce the signed document and he can be held to his promise.
There are tales of signatures written in ink which fades and becomes invisible. The law is also interested in this and all matters concerning tricky signatures.. But some signatures have faded through no trickery, The ink was unable to stand the test of time, light or moisture: The law is also interested in this in America, the quality of writing ink is protected by Federal law, if you wish to make and sell ink, your recipe must be government approved.
Standard blue‑black ink may be made from the following ingredients. The fluid base is a liter of distilled water. Dissolved in it are 5 grams of gallic acid crystals, 7.5 grams of ferrous sulphate crystals, 1 gram of tartaric acid and 3.5 grams of soluble blue dye.
The dyes and metallic salts work together to form an ink that will endure. As the air fades the dye it darkens the salts. It writes with a clean, neat line and does not penetrate through the paper, A good writing ink does not cake in the bottle, it does not separate so that you have to shake before using. It will not inure the rubber or plastic parts of a fountain pen. Most ink manufacturers improve on the standard recipe with trade secrets of their own.
There are many inks besides writing ink, Each calls for a special recipe, Laundry ink is made to withstand the water and chemicals in the washing machine. It is often made of silver nitrate and ammonia in water. India ink is made from carbon dust, glue, soap and water. This black, shiny drawing ink is water proof though it often tends to cake in the bottle and eat into metal pens.. There are printing inks and colored inks of all kinds: New recipes are invented as different needs arise,
A new ink was invented when the ball point pen was invented: The dyes and metallic salts of fluid ink were molded into solid sticks. Ink was invented by both the Chinese and the Egyptians. They molded their ingredients into solid sticks and dissolved them as needed. So maybe our new idea is not so new.
The oldest recipes used carbon dust and powdered gum. The gum formed a glue to stick the black carbon onto the paper or papyrus, Some of the old writings stand out clear and black after 4900 years: Our modern inks are even more durable, so read all the words and the fine print before you take pen in hand to sign that important document,
No sensible person will use trick inks to cheat, but here are two recipes to amuse the members of secret societies. Starch and water makes an invisible ink, So does lemon juice and water; The invisible lemon ink will turn brown over a low flames invisible starch ink turns blue in a solution of iodine.