By: M. Jamil
All of us who collects stamps have stamps in our collections which are printed by different printing processes but only few of us can distinguish them.
It is possible to collect stamps without knowing the details of their printing processes. But even the beginner may confront with errors in design varieties such as colour missing, different shade. Plates Flaws which make a considerable difference to the value of stamps. Advance collectors and specialists who embarks upon the study of stamps will need much more information about the printing, process of stamps.
It starts with the designing of stamps the artists produce the design according to given guide lines several designs may be made initially out of which one is selected by the postal authorities actual design was made larger in size which is then reduced to original intended size of stamp by photography. Then the actual printing, process started. There are four different printing processes commonly used in the manufacturing of stamps, which are as under:-
- Typography or Letter press.
- Recess or Line-Engraving.
- Lithography or offset printing.
- Digital Printing.
Typography or Letter Press:- Typography in its simplest form is the setting of loose type within a locked chase, form or frame and then printing from it. The primitive form of this process was printing from wood blocks. It is also known as surface printing. Now in modern age the design is cut by an engraver in steel plaque, is cut in relief (and reverse) and the die is made. The die is then multiplied by stereotyping or electrotyping and plates of copper or alloy are made of say 50 similar stamps which are then printed on a flat press. The copper plates have surfaces with a layer of harder metal, such as steel, nickel or chromium to give longwear in the printing press. It is found in the numerous overprints and surcharges which appear on stamps. It is used for change of country names, changing original face value of stamps and need for provisional’s usually aries in an emergency. As done by Govt. of Pakistan on several occasion like 1961 decimal surcharging done when the currency is changed from old Anna system to new decimal system (shown by some examples) also “Service” overprinting on earlier issues for official use is done by the same process.
Recess or Line Engraving:- This is a process opposite to typography in that the design is engraved in reverse on a small plate of steel. The die is recess also called in French taille douce and in Italian intagilio. When the master die is completed and the engraver has checked his work with the original by Taking a series of progressive inked proofs. It is hardened and its image is transferred under high pressure to the curved surface of the roller, a cylinder of softened steel, which now bears a positive impression of the design. Then it is made ready for use in the manufacture of the printing plate or cylinder. A softened steel plate is placed in the transfer press and under immense pressure the design image is ‘rocked in” on the plate as many time as required to form a printing plate of 100 or 50 stamps or more as per requirements.
The basic principal of recess or line engrave printing is that the ink remains in the recesses and lines after the surface of the plate has been wiped clean. In close contact with the plate, paper picks up the ink in the recessed areas, resulting in the printed stamps. The stamp design stands out in relief and the raised impression can be felt by finger tips. Throughout the process the greatest accuracy and precision is required as one stamp image may comprise up to 20,000 lines. Occasionally recess printing is combined with another process such as Typography, Lithography or Photogravure. 1989, 1994 and recent definitive stamps issues of
The Photogravure Process:- Photogravure is combination of photography and gravure (recess) printing. In this process the original design is reproduced by photography on the glass plates, on which it appears as a negative then to another glass plate where it becomes a positive the multiplication of design is done by step and repeat camera. The multi positive is then printed down on a paper coated with gelatine known as carbon tissue which is also sensitive to light. The tissue has screened surface with tiny dots or cells. The tissue is then squeegeed on to the curved surface of the copper cylinder by this process the picture is transferred to the cylinder and then the tissue is removed. Then the copper cylinder is developed in the acid bath. Then the actual printing process begins which is very similar to recess printing for multi-colour printing separate cylinder will be required for each colour. Photogravure printed stamps have an attractive photographic quality. They can be identified by soft gradations of colours and over all patterns of microscopic dots on the printed surface.
The early issues of
Lithography or Offset Printing:- Lithography was discovered by chance by a German Alois senefelder in 1798. He found that a greased impression on a well watered block of lime stone could be inked and use for printing on paper. The image could be drown in reverse direct on the stone in greasy ink or applied by means of special transfers. The blank parts of the stone being neutralized by the water (oily grease and water being incompatible).
Lithography or offset printing has become the leading commercial printing process in the world today; it combines photography with economic plate making and the fast efficient press. It involves the unique third cylinder (offset) which transfers the design image from plate cylinder to paper and it provided an immaculate end product.
The original design is used to make a colour transparency, reduction and multiplication of the design to stamps size is done either manually or on the computer. Then the colour separation is done and four basic colours cyan, Magenta, yellow, and Black are separated by scanners, then printing plates of each colour are prepared, each of which is wrapped around a cylinder of printing machine. The impression of the plate cylinder is a positive one which is then offset during the printing process on to a rubber blanket roller and then transferred or printed on to the paper in keeping with the basic oil and water principal the ink is repelled by wet (blank) parts but adheres to the inked parts and then impression is converted on paper very neatly and precisely.
Litho printed stamps from modern offset presses can be identified by sharp edges to lettering and solid colours and by honeycomb pattern of screen dots.