I hope you all are doing great and enjoying it. Continuing further the series 12 Elements of A postage Stamp Made Simple today we are going to uncover some of the other prevalent methods used in the printing of postage stamps.
As always I will try to be as informative possible. Ready? !!
This process of printing is also called as Gravure, Rotogravure or Heliogravure. This process involves the application of basic principles of photography to a chemically sensitized metal plate instead of a photographic paper. The credit for developing this technique is given to two pioneers of photography Nicephore Niepce of France and Henry Fox Talbot in England. This process was further matured by the Czech painter in 1878 Karel Klic. The process which is still used is known as the Talbot-Klic method.
The stamp design is transferred photographically onto a plate using a halftone or dot matrix screen which breaks the reproduced image into tiny dots. The chemically treated plate and the dots form depressions called the cells of varying depths and diameters as per the degrees of shade in design. Further in the process like engraving, ink is put onto the plate all across and the surface where it is to be applied is wiped clean. As a result of the process, ink is applied to the cells and deposited on the paper when the plate is pressed against it.
Gravure is most generally used for reproducing multi-colored stamps. The most commonly used colors are Red, Yellow, Blue, and Black. A typical full-color gravure stamp will be created from four printing cylinders (one for each color). Modern gravure printing may use computer-generated dot-matrix screens, and modern plates may be of various types including metal-coated plastic. Example – 1952 QE II 21/2 D Definitive.
Lithography is derived from ancient Greek words Lithos and Graphein. Lithos means stone and Graphein means “To Write”. This method of printing is based on the immiscibility of oil and water.
German Actor and author Johann Alois Senefelder invented this technique of printing in the year 1796. The positive part of the image is water repelling while the negative part is water absorbent. Hence, when the compatible printing ink and water are applied on the plate, the ink will adhere to the positive image and the water will clean the negative image.
As the name suggests it is about photographic processes to lithography. It results in greater flexibility of design. It allows the printing of large solid areas in comparison to the Photogravure technique as discussed above.
Offset or Modern Lithography:-
It is a well-refined lithographic technique used for high volume production of printed material including graphics like Books, Maps, and newspapers. A rubber-covered blanket cylinder takes the impression from the inked lithographic plate. From the “blanket” the impression is offset or transferred to the paper. Greater flexibility and speed are the principal reasons offset printing has largely displaced lithography. The term “lithography” covers both processes, and results are almost identical.
Example – Austria Scott # 622
Embossed (Relief) Printing: –
This form of printing is not considered as a major option for the printing of postage stamps. The design is embedded in the metal die. The printing happens against a yielding platen made of either leather or linoleum. The platen is then forced into the die and its depression thus transferring the design on the paper. Embossing can be done with color in exact registration with the embossed subject, without color, with color printed around the embossed area. Example – Canada Scott # 656-657
For an image or object to be printed on the stamp an exact replica of the same size as it is to be reproduced on the stamp has to be created. The science and technique of Holography is applied to create holograms. Instead of a photographic film, holography captures the image on a photoresist material. During the processing, chemicals affect certain exposed areas resulting in constructive and destructive interference.
Once the photoresist is developed a pattern of uneven ridges is formed as a result. These patterns then act as a mold. A metallic coat is applied which results in a form that is used to press copies in much the same manner as phonograph records are produced.
In a postage stamp, a typical hologram is a combination of uneven patterns on a plastic film applied to a reflective background which is usually made of silver or gold foil. This very background reflects the light making the uneven pattern of the film visible to the viewer. The viewer perceives the reflection in 3D with appropriate light. The first hologram on a stamp was published in 1988 by Austria. Example – Austria Scott # 1441
We now come to an end to this edition of 12 Elements of A Postage Stamp Made Simple. Stay tuned for more.
To Be Continued…
Self Taught Techie, Father to a budding philatelist son and a Global Business Professional Having Traveled across four continents. I have helped European and Indian Businesses to turn around and realize business objectives in 180 to 270 days. Reading & Writing is my second nature. I rekindled my childhood passion for stamps after forty years and love to collect European Pre 1960s MNH OG stamps majorly from France, Germany, and Italy.