Microprinting is the production of recognizable patterns or characters in a printed medium at a scale that requires magnification to read with the naked eye. To the unaided eye, the text may appear as a solid line. Attempts to reproduce by methods of

photocopy A photocopier (also called copier or copy machine, and formerly Xerox machine, the generic trademark) is a machine that makes copies of documents and other visual images onto paper or plastic film quickly and cheaply. Most modern photocopiers ...

image scanning An image scanner—often abbreviated to just scanner—is a device that optically scans images, printed text, handwriting or an object and converts it to a digital image. Commonly used in offices are variations of the desktop ''flatbed scanner'' ...

, or

pantograph A pantograph (, from their original use for copying writing) is a mechanical linkage connected in a manner based on parallelograms so that the movement of one pen, in tracing an image, produces identical movements in a second pen. If a line dr ...

typically translate as a dotted or solid line, unless the reproduction method can 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 widespread digital methods. While

microphotograph Microphotographs are photographs shrunk to microscopic scale.

y precedes microprint, microprint was significantly influenced by Albert Boni in 1934 when he was inspired by his friend, writer and editor Manuel Komroff, who was showing his experimentations related to the enlarging of photographs. It occurred to Boni that if he could reduce rather than enlarge photographs, this technology might enable publication companies and libraries to access much greater quantities of data at a minimum cost of material and storage space. Over the following decade, Boni worked to develop microprint, a micro-opaque process in which pages were photographed using 35mm microfilm and printed on cards using offset

lithography Lithography () is a planographic method of printing originally based on the immiscibility of oil and water. The printing is from a stone (lithographic limestone) or a metal plate with a smooth surface. It was invented in 1796 by the German a ...

. (, ) This process proved to produce a 6" by 9" index card that stored 100 pages of text from the normal-sized publications he was reproducing. Boni began the Readex Microprint company to produce and license this technology. He also published an article ''A Guide to the Literature of Photography and Related Subjects (1943)'', which appeared in a supplemental 18th issue of the Photo-Lab Index.Alt URL
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Usage

Currency A currency, "in circulation", from la, currens, -entis, literally meaning "running" or "traversing" is a standardization of money in any form, in use or circulation as a medium of exchange, for example banknotes and coins. A more general ...

commonly exhibits the highest quality (smallest size) of microprint because it demands the highest level of counterfeiting deterrence. For example, on the series 2004

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territori ...

$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 place the characters ''MP'' next to the signature line of the check; these characters represent ''microprint'' and indicate that the signature line or other check features are actually microprinted characters. The microprinted characters are used as an anti-counterfeiting feature due to their difficulty in being reproduced while the prominent MP serves as an overt deterrent warning that the item employs microprint. While microprinting at some scales may be readable to the human eye without microscopy, there is no differentiation between microprinting at these different scales. The first US postage stamp to incorporate microprinting was the American Wildflower Series introduced by The

United States Postal Service The United States Postal Service (USPS), also known as the Post Office, U.S. Mail, or Postal Service, is an independent agency of the executive branch of the United States federal government responsible for providing postal service in the U ...

in 1992. It was also the first

commemorative stamp A commemorative stamp is a postage stamp, often issued on a significant date such as an anniversary, to honor or commemorate a place, event, person, or object. The ''subject'' of the commemorative stamp is usually spelled out in print, unlike defi ...

wholly produced by offset lithography. The USPS has since issued other stamps with more complex microprinting incorporated along with dates, words, and abbreviations such as ''USPS'' and even entire stamp designs composed of microprint letters. There was passing interest in microprinting as a solution to book storage in libraries in the 1940s. Librarian Fremont Rider championed microprinting over micro-film for its reduced cost. He also suggested that entire books could be printed on the backs of library catalog cards, which are generally blank, replacing the storage of full-sized books on library shelves.

Production

Microprint of the smallest scale is only producible by hand using engraved offset printing plates or some other method of

Intaglio (printmaking) Intaglio ( ; ) is the family of printing and printmaking techniques in which the image is incised into a surface and the incised line or sunken area holds the ink. It is the direct opposite of a relief print where the parts of the matrix that m ...

Digital microtext printers utilize specially designed fonts and ink for the purpose. The ink used is most commonly

MICR Magnetic ink character recognition code, known in short as MICR code, is a character recognition technology used mainly by the banking industry to streamline the processing and clearance of cheques and other documents. MICR encoding, called the ' ...

(Magnetic Ink Character Recognition) toner particles but may also be polyester based toners and

styrene Styrene () is an organic compound with the chemical formula C6H5CH=CH2. This derivative of benzene is a colorless oily liquid, although aged samples can appear yellowish. The compound evaporates easily and has a sweet smell, although high concen ...

acrylate polymer An acrylate polymer (also known as acrylic or polyacrylate) is any of a group of polymers prepared from acrylate monomers. These plastics are noted for their transparency, resistance to breakage, and elasticity. Acrylate polymer is commonly use ...

based toners. The ink is not limited to

grayscale In digital photography, computer-generated imagery, and colorimetry, a grayscale image is one in which the value of each pixel is a single sample representing only an ''amount'' of light; that is, it carries only intensity information. Graysc ...

only, but may also use color toners or even more specialized toners containing dyes sensitive to

ultraviolet Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiation ...

infrared Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...

radiation and producing

fluorescence Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation. It is a form of luminescence. In most cases, the emitted light has a longer wavelength, and therefore a lower photon energy, tha ...

when exposed to those radiations.

Microtext and microfonts

Microprint of the scale capable by other printing methods cannot 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.

Xerox Xerox Holdings Corporation (; also known simply as Xerox) is an American corporation that sells print and electronic document, digital document products and services in more than 160 countries. Xerox is headquartered in Norwalk, Connecticut (ha ...

was acclaimed for developing a microtext font they claimed could produce characters 1/100 of an inch tall; 1/100 of an inch is equivalent to 0.72 points. In April 2015, Videojet Technologies released their 1650 High Resolution (HR) and 1620 HR Continuous Inkjet (CIJ) printers, said to be capable of printing sub-pixel size characters as small as 0.6 mm in height (equivalent to 1.70079 points). The printers use a 40-

micron The micrometre ( international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American spelling), also commonly known as a micron, is a unit of length in the International System of Un ...

nozzle that outputs more than 100,000 drops per second of ink. While these printers make microprinting faster and easier to produce digitally, they still have not reached the true sub-pixel size of less than 1 point. The smallest scale microtext a laser printer can produce is 0.5 pt.

Microstructures

Using gold

nanoparticle A nanoparticle or ultrafine particle is usually defined as a particle of matter that is between 1 and 100 nanometres (nm) in diameter. The term is sometimes used for larger particles, up to 500 nm, or fibers and tubes that are less than 10 ...

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 nano-particle ink suspension was heated using a gaussian laser; as it heated, the glass would expand due to the

thermal conductivity The thermal conductivity of a material is a measure of its ability to conduct heat. It is commonly denoted by k, \lambda, or \kappa. Heat transfer occurs at a lower rate in materials of low thermal conductivity than in materials of high thermal ...

of the gold nano-ink. In further experiments, they were able to fuse the nano-particles together into a tighter formation a continuous conductive line. Such experiments did not directly include font characters but could translate to such usage.

References

External links