Microprinting is the production of recognizable patterns or characters on a printed medium at a scale which requires magnification to be read. To the unaided eye, the text may appear as a solid line. Attempts to reproduce by methods of photocopy, image scanning, or pantograph will be translated as a dotted or solid line to the reproduction machine which cannot identify and recreate patterns to such scale. Microprint is predominantly used as an anti-counterfeiting technique due to its inability to be easily reproduced by digital methods.
Microprinting is employed as an anti-counterfeiting feature under the assumption that it would be exceptionally difficult for an individual to reproduce accurately without access to resources which are not readily available to the general public.
Currency commonly exhibits the highest quality (smallest size) of microprint because it demands the highest level of counterfeiting diterince. For example, on the series 2004 United States $20 bill, microprint is hidden within the border in the lower left corner of the obverse (front) side as well as the Twenty USA background.
Bank cheques as well as various other items of value may also commonly leverage microprinting methods, but generally not of such extreme size. For example, personal bank cheques commonly denote the characters MP next to the signature line of the check; these characters represent microprint and are used as a anti-counterfeiting feature due to their difficultly in being reproduced and simple deterrent as a warning that the item employs microprint.
Digital microtext printers utilize specially designed fonts and ink for the purpose. The ink used is most commonly MICR (Magnetic Ink Character Recognition) toner particles but may also be polyester based toners and styrene acrylate polymer based toners. The ink is not limited to grayscale only, but may also use color toners or even more specialized toners containing dyes sensitive to ultraviolet or infrared radiation and producing fluorescence when exposed to those radiations.
Microtext and Microfonts
Microprint of the scale capable by other printing methods can not be produced by a digital printer regardless of the resolution of the device . Some digital fonts are designed specifically for the purpose of microprinting. These pseudo-microprint fonts are referred to as microtext.
The smallest scale microtext can produce on a laser printer is 0.5pt.
Using gold nanoparticle inks on a glass substrate, scientists concluded that it was possible for them to control the production of print patterns to a scale of 2 microns. After printing, the nanoparticle ink suspension was heated using a gaussian laser, as it was heated, the glass would expand due to the thermal conductivity of the gold nano-ink. In further experiments, they were able to fuse the nanoparticles together into a tighter formation a continuous conductive line. Such experiments did not directly include font characters but could translate to such usage.
- Trimm, Harold H (2005). Forensics the Easy Way. Barron's Educational Series. p. 276. ISBN 0-7641-3050-1. Retrieved 2015-10-05.
- US patent 7270918, "Printing system, process, and product with microprinting", issued 2007-09-18, assigned to Eastman Kodak Company
- "Xerox Scientists Develop Microtext Font; Digitally Printing Tiny Words And Numbers Will Help Make Documents More Secure". Xerox Corporation. Retrieved 2015-10-05.
- This article incorporates public domain material from the National Institute of Standards and Technology document "Conversion Factors for Science, Engineering, and Industrial Terms" (retrieved on 2015-10-05).
- "A Comparison of Laser Printed Microprint Fonts and Practical Considerations for Use in Prescriptions" (PDF). 16 Jan 2009. p. 3. Retrieved 2015-10-05.
- Bieri, Nicole Renée (2004). Transport Phenomena in the microprinting and laser annealing of Gold Nanoparticle Inks (PDF) (Ph.D.). Zurich, Switzerland: Swiss Federal Institute of Technology. p. 167. Retrieved 2015-10-05.