- 积分
- 524
- 最后登录
- 1970-1-1
- 阅读权限
- 100
- 积分
- 524
- 帖子
- 精华
|
这是英文原文:
Making ink bulletproof
Ink: Basic ink compositions have remained unchanged for millennia, but some companies think there is still room for improvement
HAVING recognised the fallibility of human memory, people have been keeping records written with ink for over four millennia. Thanks to the durability of those early inks, the thoughts of our ancestors have been preserved. Indeed, civilisation itself could be said to depend on the persistence of the written word.
Early inkmakers mixed fine black soot with resin and water. Water suspended the soot, keeping the ink runny enough to write with. Once the water evaporated, the resin made the carbon particles stick to paper or papyrus. Today this is called pigment ink, and it remains in use in pens and inkjet printers. Another ancient way to make ink is to use dyes, in which the colour is dissolved rather than suspended in its solvent. The existence of two such venerable yet reliable technologies, however, has not prevented a number of companies from trying to make better inks.
When Newell Rubbermaid, an office- and home-supplies company based in Atlanta, began marketing one of its Uniball pens with a gel-based pigment ink as “fraud resistant” in 2005, it was not expecting a higher than normal level of demand. But thanks to the ink’s durability compared with dye-based inks and smooth writing due to the gel’s low viscosity, sales grew by around 25%
a year. Other penmakers followed suit with similar gel inks.
This ink’s durability and fraud resistance arise because the pigment particles are so small that they lodge between the fibres near the surface of the paper, making them impossible to remove without visible damage to the page, says Leighton Davies-Smith, vice-president of research and development at Newell Rubbermaid. Applying solvents like water, acetone or bleach will dissolve most dye-based pen inks, but will not remove the pigment particles. And when it comes to writing cheques or doctors’ prescriptions, an ink’s ability to resist attack is important.
Durability also turns out to have uses in more mundane situations. Nils Miller, a senior “ink and media” scientist at HP, is all too well aware of the irritation caused by the blurring of inkjet ink by highlighter pens. Some of the technology giant’s inks have been modified following discussions with highlighter manufacturers to ensure that one firm’s ink chemistry does not disagree with the other's.
The company with the reputation for the most “bulletproof” of inks, however, is Noodler’s Ink, a small American firm. The permanence of its inks relies in part on dyes that react with the surface of the paper’s cellulose fibres. Once written, they resist a variety of solvents known to be used by forgers, as well as more mundane solvents like water. The firm’s founder, Nathan Tardif, recounts stories of new customers who had handwritten documents rinsed clean in natural disasters, leaving behind sheets of paper covered with illegible, watery ghosts of their original written contents. He also argues that most industrially manufactured modern inks are too weak in both their colour saturation and durability.
The reputation of Noodler’s inks recently caught the eye of Nicholas Masluk, a graduate student at Yale University’s physics department. Mr Masluk, who has been tinkering with lasers since his high school days, thought he could make Noodler’s ink disappear without harming the paper underneath. He found that many of Noodler’s inks, as well as other fraud-resistant inks, could be removed with diligent use of a laser that he built for a few hundred dollars using parts bought on eBay. Although these inks can resist chemical attack, they can be blasted away by the infra-red output from a laser. Ink removal thus becomes a matter of careful aim and delivery of very short, high-energy bursts.
%0 |
|