Two of the major considerations are the type of paper to be used and the gum. In a sense gummed paper is spoken of as an entity, because it is rare indeed for the stamps to be gummed after printing. Generally the manufacturers must keep in mind the country which has ordered the stamps, because climate has its definite effects on paper and gum. Paper, too, sometimes has a marked effect on the present-day value of certain stamps. In the case of Hawaii's Kamehameha IV stamp (Scott's type A11 ), three papers were used. The one printed on horizontally laid paper is priced at $29.00 unused, as compared to $12.00 for the vertically laid paper, and $6.00 for the printing on thin wove paper.

Thus a knowledge of paper is important. It is unfortunate the publishers of the Scott Standard Postage Stamp Catalogues refuse permission to use their descriptions of paper in general articles since these descriptions tie in so closely with the catalogue.

Paper is very briefly described as a felted web, fabric or tissue of cellulosic fibres and of appropriate uniform thickness, strength, color and surface. Among the materials used for the manufacture of paper are rags and woodpulp, wood, hemp, jute, straw and waste paper. Rags are invariably used for the better grades of paper, but woodpulp is the most widely used.

In any case the material is cut down and shredded, and mixed with chemicals to break down the structure and to bleach to the desired color. At the end of the long process the material, known as "half-stuff," is ready to be made into paper. This is done by further "bruising" which may be greater or less, but makes for grades of paper in direct relationship to the amount of breaking down. The "half-stuff" when ready goes into a "pond" that feeds the pulp onto a screen. As this screen moves along the loose water drains and is shaken off, and the material goes through wet presses and a smoothing press, and finally emerges onto the large rolls.

Such paper, whether dried over a fabric screen or close wire screen, is known as "wove" paper and is the most commonly used for stamps today. Some of this wove paper is tinted during manufacture and is described as thin bluish paper, blue paper, violet paper and so on.

In other instances the face of the paper is given an overall surface color so that it looks like colored paper on one side while the reverse is white.

Laid paper is produced in the same manner, generally, as wove paper, but the screening is parallel and therefore the paper has a ribbed effect. Where these lines are widely spaced the paper is known as batonne. Where the wire screen is widely spaced in the form of squares the paper becomes quadrilled.

Other forms of paper used in stamp production are pelure, or semi-transparent paper; silk; granite; manila; ruled paper; and paper with moire overprint.

Some paper, as it passes through the presses in the final stages of manufacture, is impressed by wire or metal devices. When the paper is finished it has impressed thin spaces which show up against light or against a black surface when laid face down. This is known as a watermark.

Watermarks, too, have a decided bearing upon the value of certain stamps. Taking a United States stamp as an example, the So-cent violet of iqm appeared with a singlelined "U.S.P.S." watermark and is catalogued at $30.00 unused. In the same year it appeared with a double-lined "U.S.P.S." watermark and is valued at $15.00. Both had the same perforations, so the onlv distinguishing factor was the watermark, and that means a difference of $15.00, catalogue price.

In all there are perhaps 300 different forms of watermark used on stamps, including such styles as stars, crowns, lines, letters and coats of arms, garters, heraldic emblems, flowers and anchors. One could form a very interesting collection of the various watermarks on stamps.