Some friend of mine asked me "What it is the invisible ink !?!?" so for that I try to explain him in this post what it's all about. The Invisible ink, also known as the 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 offsteganography.nvisible 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. 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.For practical reasons, the inks are listed here according to their method of development. Any invisible ink can be made visible by someone who is sufficiently determined, but the limitation is generally time available and the fact that one cannot apply hours of effort to every single piece of paper. Thus successful use of invisible ink depends on not arousing suspicion that invisible ink may be present. It must be understood however that some inks - particularly those of organic origin or those consisting of a mixture of several chemicals - may be made visible by several methods. For example, invisible writing with soap water may be made visible either by heat, reaction with phenolphthalein, viewing under ultraviolet light, or by placing the page inside an iodine fume cupboard. So my dear friend, I hope this little review of mine was usefull for you, and now you've got some ideas what the invisible ink is !!!