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Invisible ink, also known as security ink, is a substance used for writing, which is invisible either on application or soon thereafter, and can later be made visible by some means. Invisible ink is one form of steganography. == General Application and Use == Invisible ink can be applied to a writing surface with a specialty purpose stylus, stamp, fountain pen, toothpick, calligraphy pen or even a finger dipped in the liquid. Once dry, the written surface looks as if it were blank, with a similar texture and reflectivity as the surrounding surface. The ink can be later made visible by different methods according to the type of invisible ink used. The ink may be revealed by heat or by application of an appropriate chemical, or it may be made visible by viewing under ultraviolet light. Inks which are developed by a chemical reaction may depend on an acid-base reaction (like litmus paper), reactions similar to the blueprint process, or any of hundreds of others. Developer fluids may be applied using a spray bottle, but some developers are in the form of vaporous, e.g. ammonia fumes used to develop phenolphthalein ink. There are also toy invisible ink pens which have two tips—one tip for invisible ink writing, and another tip for developing the ink. Invisible ink is sometimes used to print parts of pictures or text in books for children to play with, always including a "decoder pen" which is used to show the invisible parts of texts or pictures, thus revealing answers to questions printed in regular ink or completing missing parts of pictures. Security marker pens or UV Markers with fluorescent ink that glows when illuminated with a UV light is often used to invisibly mark valuable household items in case of burglary. There are especially security maker pens formulated for writing on non-porous surfaces such as glass, plastics, metals, etc. The inks that have been applied and can then be identified by using a black light or other UV light source. Security marker pens can be obtained commercially and are widely used as a crime countermeasure. Some commercially available invisible inks glow very brightly, in a variety of colors, under UV light. This makes them suitable for use in readmission such as hand stamping. There some invisible ink types that can only be invisible when applied to certain types of surfaces, but are still visible on others. Some vendors now offer invisible ink for use in computer inkjet printers. Such inks are usually visible under ultraviolet light. Typical uses include printing information on business forms for use by the form processor, without cluttering up the visible contents of the form. For example, some United States Postal Service mail sorting stations use UV-visible ink to print bar codes on mailed envelopes giving routing information for use by mail handling equipment further down the line before delivery. Very rarely, invisible ink has been used in art. It is usually developed, though not always.〔Daniel C. Boyer has had a number of non-decoded invisible ink drawings "exhibited." His works have included ''The Masters at the Point of Spidery Old Age''.〕 There are artists who use the effect in conjunction with invisible and other reactive inks and paints to create a variety of effects when used in conjunction with UV lights. An E2E voting system called Scantegrity II uses invisible ink to enable the voter to obtain a confirmation code only for the voted selection. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「invisible ink」の詳細全文を読む スポンサード リンク
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