2. Edwardian stamps.
3. Parcels post stamps.
4. Commemorative stamps, as long as they are not issued for speculative purposes.
5. The line-engraved stamps of Great Britain (see following chapter).
Just as certain countries or groups present exceptional chances for specializing, so others offer but poor opportunities. In cases where the issues are few, or where the stamps are high priced, the path of the specialist is beset with difficulties, and should not be followed.
The first need of the collector who intends to pay particular attention to an individual group of stamps is a blank album containing about two dozen pages. Into this volume should be gathered the specimens bearing on the chosen section as they are obtained. Less formality and regularity will be called for when placing the stamps in this book than was demanded in the general collection; in other words, the stamps need not be ranged so precisely according to age and value. Whatever method is adopted should be used rather for contrasting and comparing minor details than for showing complete issues. In the stamps of Great Britain, for instance, we should not place, say, the Edwardian issue in two or three methodical rows, the halfpenny first, followed by the penny, then the three-halfpenny, and so on, up to the one pound. We should group together the varieties of, say, the threepenny, which include such shades as purple on yellow, purple on lemon, deep purple on lemon, dull purple on yellow, and which are found perforated 14, also 15 by 14. When placed side by side, these various shades and perforations will show up clearly; but if scattered over two or three pages of the album, their meaning will be lost entirely.
It is clear that the specialist must know a good deal more about his stamps than was demanded of the general collector. In the first place, he must be able to distinguish one form of printing from another. For his benefit it may be well to mention that the chief processes employed in printing stamps are (1) Typography, (2) Lithography, and (3) Engraving.
Typography, or surface-printing, is the process employed in the production of our current British stamps. A die is cut with the design standing out in relief—i.e., the portions which are to receive the ink are raised. From this die a number of identical moulds are taken and ranged side by side. They are then clamped together and placed in an electro bath which deposits a layer of copper upon the moulds. When the coating is deemed sufficiently thick, the electrical action is arrested, the moulds are removed, and the copper plate reveals a number of replicas of the original die.
Lithography is a process which results from etching on stone. A piece of stone possessing a flat surface is taken, and the design drawn in ink upon it either by hand or some mechanical means. The surface of the stone is then flooded with a weak acid, which eats away the unprotected parts, but leaves untouched the parts covered by the greasy lithograph ink. The stone is then sponged with water, and printer's ink, also greasy, applied. This latter adheres only to the lines made by the lithographic process, with the result that impressions of the design may be transferred to paper. Lithography, it should be added, is only suitable in cases where comparatively few copies are needed, or where a temporary issue must be printed expeditiously. It is a process which demands but little capital outlay, a fact which has made it a favourite means of stamp-producing among the poorer republics of South America. With forgers, too, it has gained favour in their work of imitating genuine stamps.
Engraving, known variously under the name of copper-plate printing, engraving in taille-douce, and line-engraving, produces the finest stamps figuring in our collections. The process is worked much on the lines detailed for typography, but the main difference is that in the latter the design is printed by the raised parts of the block, whilst in the former the recessed parts produce the lines which form the design.