View source for Microprinting

{{Short description|Printing at a small scale}}
{{For |the archival film processing technique that reproduces images of documents |Microform}}
{{multiple image|perrow = 1|total_width=250
| image1 = USD100-microprint USA.jpg
| image2 = Usdollar100front.jpg
| footer = Close-up of microprint incorporated on US$100 paper currency, hidden in the collar of Franklin's shirt
}}
'''Microprinting''' is the production of recognizable patterns or characters in a printed medium at a scale that typically 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]], [[image scanning]], or [[pantograph]] 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 [[counterfeit|anti-counterfeiting]] technique, due to its inability to be easily reproduced by widespread digital methods.

While [[microphotograph]]y precedes microprint, microprint was significantly influenced by [[Albert Boni]]<ref name=price>{{cite journal |last1=Price |first1=Miles |title=The Microcard Foundation |journal=American Bar Association Journal |date=April 1953 |volume=39 |pages=304–305 |url=https://books.google.com/books?id=VSQMvwRpV_8C&q=microprint+originally+invented+by&pg=PA304 |access-date=9 October 2015 |publisher=American Bar Association |issn=0747-0088}}</ref> 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]]. ({{US patent |2260551A}}, {{US patent |2260552A}})  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|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.<ref name=metcalf>{{cite journal |last1=Metcalf |first1=K. D. |title=The Promise of Microprint: A Symposium Based on The Scholar and the Future of the Research Library |journal=College & Research Libraries |format=PDF |date=1945-03-01 |volume=6 |issue=2 |pages=170–183 |issn=2150-6701 |doi=10.5860/crl_06_02_170 |url=http://crl.acrl.org/content/6/2/170.full.pdf+html |archive-url=https://web.archive.org/web/20140625082645/http://crl.acrl.org/content/6/2/170.full.pdf+html |archive-date=2014-06-25 |access-date=2015-10-08 |doi-access=free |hdl=2142/35340 |hdl-access=free }} [https://www.ideals.illinois.edu/bitstream/handle/2142/35340/crl_06_02_170_opt.pdf?sequence=2 Alt URL] {{Webarchive|url=https://web.archive.org/web/20151121065946/https://www.ideals.illinois.edu/bitstream/handle/2142/35340/crl_06_02_170_opt.pdf?sequence=2 |date=2015-11-21 }}</ref><ref name=erickson>{{cite journal |last1=Erickson |first1=Edgar L |title=Microprint: A Revolution in Printing |journal=Journal of Documentation |date=March 1951 |volume=7 |issue=3 |pages=184–187 |doi=10.1108/eb026173 |issn=0022-0418}}{{Subscription required}}</ref><ref name=boni>{{cite journal |last1=Boni |first1=Albert |journal=American Documentation |date=Summer 1951 |page=150 |url= https://www.proquest.com/openview/bc86eb894470ea44293671f4136cf9ad/1 |format=PDF |title=Microprint |volume=2 |issue=3 |access-date=2015-10-08|doi=10.1002/asi.5090020304 |url-access=subscription }}</ref>

==Usage==
[[Currency]] commonly exhibits the highest quality (smallest size) of microprint because it demands the highest level of counterfeiting deterrence.<ref name=trimm>{{cite book|last1=Trimm|first1=Harold H|title=Forensics the Easy Way|publisher=Barron's Educational Series|year=2005|url=https://archive.org/details/forensicseasyway0000trim|url-access=registration|quote=Microprinting.|isbn=978-0-7641-3050-2|page=[https://archive.org/details/forensicseasyway0000trim/page/276 276]|access-date=2015-10-05}}</ref>  For example, on the series 2004 [[United States]] [[U.S. twenty dollar bill|$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.<ref name=trimm/>

[[File:Microprint.gif|thumb|''MP'' microprint commonly used on personal bank cheques]]
[[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 cheque; these characters represent ''microprint'' and indicate that the signature line or other cheque 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]] in 1992.  It was also the first [[commemorative stamp]] 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.<ref>{{cite web|url=http://postalmuseum.si.edu/blog/Chenevert_page_1.pdf|title=Security Features of United States Postage Stamps 1974-2009|page=1|last1=Chenevert|first1=James|access-date=2015-10-07|archive-date=2015-10-17|archive-url=https://web.archive.org/web/20151017203400/http://postalmuseum.si.edu/blog/Chenevert_page_1.pdf|url-status=dead}}</ref>

{{Further|Security printing}}

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.<ref>{{cite book |last1=Rider |first1=Fremont |title=The scholar and the future of the research library, a problem and its solution |date=1944 |publisher=Hadham Press |location=New York}}</ref>

==Production==
[[File:Engraving.jpg|thumb|Preparing a lithographic printing plate]]

Microprint of the smallest scale is only producible by hand using engraved [[offset printing]] plates or some other method of [[intaglio (printmaking)]].

[[File:MICR char.svg|thumb|MICR]]

Digital microtext printers utilize specially designed [[font]]s and ink for the purpose.  The ink used is most commonly [[MICR]] (Magnetic Ink Character Recognition) toner particles but may also be [[Polyester resin|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.<ref name=us7270918b2>{{cite patent|country=US|number=7270918|status=patent|title=Printing system, process, and product with microprinting|gdate=2007-09-18|fdate=2004-11-18|pridate=2003-12-24|inventor1-first=J|inventor1-last=Blood|inventor2-first=C|inventor2-last=Leonard|inventor3-first=J|inventor3-last=Crichton|inventor4=T. Plutchak, G. Rombola|assign1=Eastman Kodak Company|url=http://www.google.nr/patents/US7270918}}</ref>

[[File:Microfont.png|thumb|right|Examples of several microfonts used in digital microprinting]]

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.<ref name=us7270918b2/>

[[Xerox]] was acclaimed for developing a microtext font they claimed could produce characters 1/100 of an inch tall<ref name=xerox>{{cite web|url=http://www.xerox.com/innovation/news-stories/microtext/enus.html|title=Xerox Scientists Develop Microtext Font; Digitally Printing Tiny Words And Numbers Will Help Make Documents More Secure|publisher=Xerox Corporation|access-date=2015-10-05}}</ref> (equivalent to 0.72 [[Point (typography)|points]]).<ref name=inchpoint>{{NIST-PD|article=Conversion Factors for Science, Engineering, and Industrial Terms|url=ftp://ftp.nist.gov/pub/dataplot/other/reference/CONVFACT.TXT|accessdate=2015-10-05}}
</ref>

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&nbsp;mm in height (equivalent to 1.70079 points). The printers use a 40-[[Micrometre|micron]] 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.<ref name=videojet>{{cite press release|url=http://www.pmpnews.com/news/enhanced-microprinting-technology-featured-latest-videojet-1000-series-release-150410|publisher=UBM Canon|title=Enhanced Microprinting Technology Featured in Latest Videojet 1000 Series Release|last1=Anderson|date=2015-04-09|access-date=2015-10-07}}</ref>

The smallest scale microtext a laser printer can produce is 0.5&nbsp;pt.<ref name=troy>{{cite web|url=http://www.troygroup.com/contact/downloads/TROY_Microprint_Whitepaper_011609.pdf|title=A Comparison of Laser Printed Microprint Fonts and Practical Considerations for Use in Prescriptions|date=16 Jan 2009|page=3|access-date=2015-10-05|url-status=dead|archive-url=https://web.archive.org/web/20151008060618/http://www.troygroup.com/contact/downloads/TROY_Microprint_Whitepaper_011609.pdf|archive-date=2015-10-08}}</ref>

==Microstructures==
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 nano-particle ink suspension was heated using a [[Gaussian beam|Gaussian laser]]; as it heated, the glass would expand due to the [[thermal conductivity]] 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.<ref name=nano>{{cite thesis|type=Ph.D.|degree=D.Sc.|date=2004|url=http://e-collection.library.ethz.ch/eserv/eth:27519/eth-27519-02.pdf|title=Transport Phenomena in the microprinting and laser annealing of Gold Nanoparticle Inks|publisher=Swiss Federal Institute of Technology|location=Zurich, Switzerland|first1=Nicole Renée|last1=Bieri|page=167<!--appears as page 201 in the digital pdf, marked as page 167 on the page -->|access-date=2015-10-05}}</ref>
<!-- https://escholarship.org/uc/item/9995d5b8#page-91 see page 91 of PDF. potential content to further this section -->

==See also==
* [[Machine Identification Code]]
* [[Microdot]]
* [[Microfilmer]]
* [[Microform]]
* [[Microphotograph]]
* [[Point (typography)]]
* [[Preservation (library and archival science)]]

==References==
{{Reflist|40em}}

==External links==
*[http://babel.hathitrust.org/cgi/imgsrv/download/pdf?id=mdp.39015009825780 ''A Guide to the Literature of Photography and Related Subjects'' (1943)] by Albert Boni

{{Optical storage media}}
{{Typography terms}}
{{Authority control}}

[[Category:Documents]]
[[Category:Archival technology]]
[[Category:Film formats]]
[[Category:Storage media]]
[[Category:Money forgery]]
[[Category:Steganography]]
[[Category:Typography]]
[[Category:Packaging]]
[[Category:Security]]
[[Category:Authentication methods]]
[[Category:Engraving]]