A Glossary of Terms for the Collector of United States Stamps

G - prefix letter used by Guilford Gravure, Inc. in front of the plate number on its modern stamp production.

GPO - see 1.) General Post Office  2.) Government Printing Office.

Gaps in Tagging - tagging gaps and bright lines as seen under ultraviolet light.  They can be caused by: the gap where tagging plates butt together; screws and clips used to hold tagging mats to their cylinders; the scraping action of perforating wheels and guides; scratches and foreign matter on the tagging plates or rollers; cleaning solvent residue on the tagging rollers; etc.

Gauge - see Perforation.

General Delivery - the delivery of mail over the post office counter to customers in a community without local delivery or post office boxes, or to other persons, such as travelers, who lack an address in the community.

General Post Office - typically the main post office in a given city.

German Occupation Issues - see Allied Military Government Stamps.

Ghost Tagging Images - portions of a stamp's image, or more commonly the plate number from the just previously printed plate, setoff on the following printed stamp.  Ghosts occur during offset tagging and are usually faint, and slightly off center.

Giori Press - sheetfed, multicolor, intaglio,  rotary presses that were first used to print the 4¢ American Flag stamp of 1957 (Scott 1094).  This press could print in three colors and is best known for the bright, multicolored commemorative  postage stamps of the late 1950s through the 1970s.

Glow-Bar Tagging - vertical bar of tagging used on some Postal Stationery issues.  Size varies, and the bar is usually to the left of the indicium.  Examples: 1982 20¢ Purple Heart stamped envelope  (Scott U603); 1987 14¢ Plow postal card  (Scott UX115).

Government Coil - coil stamps produced by the BEP, or by a private manufacturer working under contract to the Post Office, as opposed to coil stamps produced by a private company from BEP sheets for its own proprietary purpose.

Government Flight - air mail flight on which the pilot was a federal employee, as opposed to Contract Air Mail Flights.

Government Printing Office - federal agency that has printed all postal cards since 1910, and many aerograms.

Grainy Tagging - tagging with an uneven, grainy appearance when viewed under ultraviolet light, as opposed to even or mottled tagging.

Gravure - a printing process utilizing cylinders (a separate one for each color) upon which the image has been recessed in dots by photographic and chemical means.  The web is printed directly from these cylinders.  The first stamp to be produced by gravure was the 1967 5¢ Eakins Commemorative, Scott 1335.

*Great Americans Issue - the longest running definitive stamp series, issued between 1980 and 1999.  Its 63 face different stamps give it more face different stamps than any other series.  The first Scott number is 1844.

Gridiron Cancels - common 19th century cancellations consisting of rows of parallel lines enclosed in a circle.

*Grill - 1.) a device with a waffle-like pattern of parallel rows of raised points that is used to break the paper fiber of stamps  2.) the waffle-like pattern of raised, broken points on a stamp, created by a grilling device.  Certain 19th century stamps were grilled as a security device.  By breaking the fibers of a stamp's paper it was hoped to make the ink used in cancellations more completely absorbed and thus harder to wash out.

Gripper Cracks - cracks formed in a curved rotary press plate at the spot where clamps hold the plate to the press.

Guide Dot - a dot placed upon an engraved plate as a guide to the siderographer in properly placing subjects upon the plate.

Guide Line Block - a block of stamps that is divided in half, either vertically or horizontally, by a guide line.  See also Center Line Block

Guide Line Pair - a pair of flat plate stamps with a segment of a guide line between them.  This term is most commonly used in association with coil stamps.

Guide Lines - lines inscribed on a plate as an aid to perforating or cutting a sheet into panes.  Guide lines are NOT the same as Joint Lines.

Guilford Gravure Inc. - private printer of postage stamps.  Their association with stamp production began when their plant and presses were used by BEP employees to print the 1970 Anti-Pollution Issue (Scott 1410-1413) and 1970 Christmas stamps (Scott 1414-1418).

*Gum - the adhesive substance applied to the back of stamps that enables a stamp to be affixed to an envelope.  see Water-activated Gum and Self-Adhesive Stamp

Gum Breakers - the horizontal or slightly diagonal impressions created on the gum of rotary sheet stamps by physically "breaking" the gum.  Breakers look something like speed-bumps, and were created as part of the perforating process.  The intended purpose of breakers was to reduce the tendency of panes to curl.  Gum breakers are known in several configurations, and were used from circa 1920 until as late as 1970.

Gum Crease - a naturally occurring crease found on flat plate stamps, usually caused by handling during production.

Gum Ridges - vertical ridges of gum on the backs of rotary sheet stamps, created as a part of the printing process when gum was applied to stamps using rollers that had ridges engraved on them.  Ridges are known in two varieties: 1/16 and 1/32 of an inch apart.  The intended purpose of ridges was to make stamps adhere better.  They were used in the 1920s and 30s.

Gum Skip - a generally small area on a stamp to which no gum adhered during production.  Gum skips are most commonly encountered on flat plate stamps from the first part of the 20^th century.

Gutter - the margin between the panes of a sheet of stamps.  The gutters of mid-20th century sheets may contain markings such as dashes or crosses that aid in perforation.  The gutters of modern sheets, containing more than the traditional four panes, may contain other marginal markings, including plate numbers.  The margin that runs around the outside edge of the sheet is NOT a gutter.  Gutters are only found between panes.

Gutter Block - a block of stamps that includes complete stamps from two or four adjacent panes, and the gutter or gutters between them.  Gutter blocks are generally not available to collectors when the stamps are sold only in pane form.  They are available to collectors when stamps are sold in sheet form.

Gutter Pair - a pair of complete stamps separated by a gutter.  A gutter pair is of more value than a corresponding guttersnipe.

Guttersnipe - a stamp or stamps to which is attached the full adjacent gutter, including perforations, and sometimes including portions of the stamp(s) on the other side of the gutter.  A guttersnipe is a freak that may be caused by a paper fold or a misregistration in the production process.

HPO - see Highway Post Office.

Hammarskjold Special Printing (Scott 1203) - a printing ofthe 1962 Hammarskjold Issue with the yellow background inverted.  When several panes of the Hammarskjold stamp unintentionally reached the public with the background inverted, the Postmaster General intentionally printed a large quantity of the error for sale to collectors.

Handback - a cover that is cancelled at a post office window and returned to the person presenting it.  A handback cover is never carried in the mailstream.

*Hand Cancel - a cancellation applied with a hand-held device, as opposed to a cancellation applied by machine.

Handstamp - 1.) a hand-held device used by postal worker to cancel a stamp or apply a postal marking  2.) the impression left by a handstamp on a cover.

Hardening - the process of taking a soft die, roll, or plate and making it metallurgically hard.  In the process of producing engraved stamps, the design can only be worked into soft steel, but is generally only transferred from hard steel.  The hardening process can be reversed.  That is, a hardened die, roll or plate can be made metallurgically soft again.

Hartford Manufacturing Co. - manufacturer of early 20th century stamped envelopes.

Helicopter Mail - mail transported by helicopter between an airfield and a post office.

Hidden Images - obscured images, placed on certain modern postage stamps, which can be viewed with a Stamp Decoder.

Highway Post Office - a motorized vehicle used by the Post Office.  As it traveled along a route connecting a number of post offices, mail would be picked up, sorted and delivered (to post offices, not individual customers).  The last HPO ran in 1974.

Hologram - an image which, viewed at an angle, appears to be three-dimensional.  Holograms are used on selected modern postage stamps and postal envelopes.

Hopkinson Memorial Award - prestigious award, given annually by the United States Stamp Society, for the best article published in The United States Specialist.

Hopkinson Trophy - prestigious award given at the annual meeting of the United States Stamp Society for the best exhibit of 20th century material by a USSS member.

Horizontal Half - a fractional use of a stamp - a horizontal bisect - a stamp cut in half horizontally.

Huck Multicolor Press - a nine-color, webfed, intaglio press used by the BEP from 1968 to 1976.  The Huck Press could print, tag, gum and perforate stamps in one continuous operation.  The first stamp printed from this press was the 1968 Christmas stamp, Scott 1363.

Huck-Cottrell Presses - a group of high speed, intaglio, webfed presses first used to print the bi-color International Red Cross stamp of 1952 (Scott 1016).  These presses were similar to a Stickney press, but faster.  The last Huck-Cottrell presses were decommissioned in 1985.

Hunting Permit Stamps - see Duck Stamps

Hybrid Proof - generally, a 19th century plate proof cut close and most typically mounted on India paper, and then mounted on a larger piece of cardboard.  It may also show die sinkage.  Some hybrid proofs were made from die proofs.  Hybrid proofs resemble Large Die Proofs.

Hyphen-Hole Perforations - perforations in the shape of comparatively large rectangles, applied to imperforate stamps by Schermack Mailing Company, for use in affixing machines.