Illustrated Glossary

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S20, S30 and S40

Marginal imprints on the US 170 subject coil stamp rotary press plates that indicated that the outer frame lines on the stamps had been cut shallower to accommodate the new, rotary press method. Although the exact meaning of the markings is not known, the following explanation has been given by Miers and McLemore among others: The normal frame lines had a tendency to bleed when printed from the curved rotary press plates and an experiment was made with the frame lines cut 20% shallower, the "S20" plates. The frame lines still bled, and an even shallower cut was experimented with; these plates were marked "S40". This probably proved too light and another experiment with the frame lines cut 30% as deep as the normal stamp proved effective. These plates were marked "S30". We gather that since this proved effective, no further experiments were made and the marginal "S" markings were dropped on subsequent rotary plates.

Savings Stamps

Stamps issued by the Post Office Department that were redeemable in the form of U.S. Savings Bonds and in the form of credits to U.S. Postal Savings accounts, as well as in the form of U.S. War and Defense Bonds.

Schermack Perforations

The Schermack Mailing Machine Company of Detroit, Michigan, originally the Detroit Mailing Machine Company produced some of the early stamp vending and affixing machines from 1906-1926. They privately applied perforations to imperforate flat plate stamps for use in its vending and affixing machines.

Secret Mark

The Schermack Mailing Machine Company of Detroit, Michigan, originally the Detroit Mailing Machine Company produced some of the early stamp vending and affixing machines from 1906-1926. They privately applied perforations to imperforate flat plate stamps for use in its vending and affixing machines.

Seebeck Issues

Stamps issued by various Latin American countries from 1890-1899, produced by the Hamilton Bank Note Company of New York. Hamilton s agent Nicholas Seebeck agreed to print new issues of stamps each year at no charge, but in return retained the right to sell remainders and reprints to stamp collectors. This seemingly innocent gesture created a storm of controversy in the philatelic world, ruining Seebeck s reputation and darkening the philatelic standing of the countries involved, a stain that has not completely lifted more than 100 years later. Ironically, many of the Seebeck issues are prized more than the contemporary issues of non-Seebeck Latin American issues.


The portion of the paper on a sheet or pane of stamps that does not include the stamps themselves, in other words the outer edge or margin of a sheet of stamps. The selvage may include markings such as the printer s imprint, plate numbers, etc.


Two or more adjoined stamps having different colors, denominations, or designs.

Shanghai Overprints

A surcharged overprint on the US Washington Franklin perf 11 issue of 1919, which in effect doubled the cost of purchasing the stamp in Shanghai, China if not paid in U.S. currency.


A large unit of stamps from which panes may be cut. Although commonly, but not correctly, called "sheets" by the general public as well as many collectors, it is a pane of stamps that is sold by the post office. The sheets of many classic U.S. stamps had only two panes, many of the Bureau issues had four panes, while modern sheets may have six or more panes.

Sheet Waste

Not to be confused with "coil waste", "sheet-waste" stamps were produced from remnants of the rotary press sheet stamps of the rotary one cent Washington Franklin, the rotary one cent of 1922 and the rotary two cent black Harding. One theory has it that these rare stamps were salvaged and perforated (perf 11) as an economy measure. Another and just as plausible theory is that these rarities were the result of experimentation with the perf 11 perforations on the new rotary sheets (rotary sheet stamps had been perforated 10 and were proving difficult to separate). Whatever the case, the rotary sheet waste stamps are an interesting and highly sought after lot. A census of these stamps may be found on the Siegel web site.

Short Set

An incomplete set of stamps, missing one or more of the more expensive stamps in the set. A short set of the Trans-Mississippis, the one cent through ten cent issues (US 285-290), missing the three most expensive stamps, the fifty cent, one dollar and two dollar stamps (US 291-293), is shown.

Siderographer (Siderography)

A skilled craftsman who made printing plates by transferring the design on the engraved dies to first a transfer roll and then the engraved plate. This job was especially difficult since each design needed to be "rocked " in at exactly the right position. Often the siderographer would punch his initials on the plate, usually in the lower left margin.

Silk Paper

A type of paper containing small pieces of colored silk threads, sometimes found on the U.S. classics and Bank Notes, and used to produce certain revenue stamps.

Single Line Watermark

A watermark used by the Bureau of Engraving and Printing that replaced the double-line USPS watermark. The single-line USPS was smaller and a little farther apart in the hopes that it would be less intrusive and affect less paper shrinkage than the double-line USPS. The single-line USPS watermark is found primarily on certain Washington Franklins issued from 1910 until about 1914, but also on postage dues of the same era and all parcel post and parcel post postage due stamps. Studying the watermarks on U.S. parcel post stamps would be of great help in learning how to identify the single-line USPS watermark, since all parcel post stamps must have the watermark.


A controversial technique of encasing stamps in a hermetically sealed container after authentication and grading, and that prohibits any further alteration. Slabbing is a common and accepted practice in the coin world, but has generally not been well received among philatelists. There is some debate as to whether paper deteriorates in a hermetically sealed environment and there is evidence to suggest that is the case. On the other hand, the hermetic seal can be broken (and the stamp re-expertized) at any time, and a slabbed stamp guarantees an investor that they are getting what they paid for.

Small Banknotes

(US Scott #219-229) Stamps produced by the American Bank Note Company for the U.S. regular issues of 1890-1893. "Small" or "Baby" distinguishes these Bank Note stamps from the earlier, and larger Bank Notes (US 134-218). The Bureau of Engraving and Printing took over production of U.S. stamps in 1894, but used the same designs as the "small" Bank Notes. The Bureau's stamps may be distinguished from American's by the presence of triangles in the top of the design.

Socked-on-the-nose (SON - SOTN)

(Bull s Eye Cancel) a stamp with a clear postmark in the dead center of the stamp.

Souvenir Sheet

A small sheet containing one or more valid postage stamps, surrounded by a large margin with marginal inscriptions promoting the philatelic event for which it was issued.

Space Filler

A damaged stamp that is used to fill the designated space in a stamp album until a better copy can be found.

Special Delivery

A service that provided for delivery of an item after normal post office hours, meaning the item would be delivered that afternoon or evening rather than the next day. The first U.S. special delivery stamp was issued October 1, 1885.

Special Handling

A service that provided an upgrade in the handling of parcels to the status of First Class mail.


An overprint on stamps, not valid for postage, most often for distribution to the Universal Postal Union for identification purposes and to the philatelic press for publicity purposes.

Split Grill

A stamp showing portions of two or more grills.

Stampless Cover (Letter)

A letter that does not have a postage stamp attached, often found on covers before the introduction of the postage stamp or prior to the time prepayment of postage was required.

Star Plates

Flat plates with an imprint containing a star in the margin near the plate number. Stars were used to indicate an experimental spacing of 3mm between some of the stamps, rather than the normal 2mm spacing. The star alerted workers that the printed sheets had the unusual spacing and to make the necessary adjustments. The star plates are found on certain Washington Franklin sheets, on the two cent Lincoln of 1909 and some of the definitives of the 1922 Series.

Stitch Watermark

A watermark comprised of straight or zigzag parallel lines caused by the stitching together of the ends of cloth aprons on which the pulp is assembled to make paper. Some sources state that stitch watermarks may be found on nearly every stamp issue.

Straight Edge

A sheet stamp from the margins with one or two sides naturally lacking perforations. Straight edges are usually not as desirable as fully perforated stamps, but as one wag put it, "at least I know my stamp has not been re-perforated."


Three or more unseparated stamps in a row. Many of the early Bureau issues were saved in strips of three with the plate number and imprint intact as shown at right. Later, collecting the entire block came into vogue, hence "plate blocks".

Sulphuretted (similar: Oxidized)

The term applies to stamps which have become discolored or darkened due to minute amounts of sulfur in the air.


An overprint that either raises or lowers the face value of a stamp or item of postal stationery.

Sweated gum

Stamps that have been stored in conditions that are either too warm or too humid and usually in tightly packed glassines, melting the gum into a smooth, shiny condition.