Stencil Hand stencils , made by blowing pigment over a hand held against a wall, have been found in Asia and Europe dating from over 35, years ago, and later prehistoric dates in other continents. Stencils may have been used to colour cloth for a very long time; the technique probably reached its peak of sophistication in Katazome and other techniques used on silks for clothes during the Edo period in Japan. In Europe, from about they were commonly used to colour old master prints printed in black and white, usually woodcuts. In China seals were used since at least the Shang dynasty.
BBC - Future - Why printers add secret tracking dots
Discover more of our picks. They had spent the last two days investigating a top secret classified document that had allegedly been leaked to the pres s. Shortly after a story about the leak was published, charges against Winner were made public. They discovered something else of interest: They were barely visible to the naked eye, but formed a coded design. After some quick analysis , they seemed to reveal the exact date and time that the pages in question were printed:
Data can be like that. But there comes a time when you have to decide…are you going to make a commitment to this data? Are you willing to make decisions and plan out long term strategies and goals using this data? Think about that date with the man or lady who seemed a little off kilter.
All of this is also available with quick drying ink to permit printing on surfaces such as metal and plastic. In addition to number, date, time and text, this device can also print graphics and barcodes. With the MP ink, it is also possible to print on non-absorbent surfaces such as metal and plastic.