Stamp printing methods - an introduction
PRINTING of POSTAGE STAMPS
Three main types of printing stamps, each with a variety utilizing photography.
However a design is produced, whether the result is positive or negative, the result will be
reversed in direction, left to right. So either the original design must be created in a reversed
direction so that the print will produce the desired orientation, or intermediate dies produced
from a design on the desired orientation and thus in the reversed mode for printing.
1. Names: Intaglio, engraving, etching, recess.
Process: image on plate produced by hand engraving, or photogravure and the design is positive,
i.e., the recessed lines produce the design. Ink is poured into the recesses of a plate, the raised
portion of the plate is clean. Dry (gummed) paper may be pressed into the inked recesses, or wet
paper (ungummed) pressed into the recesses. In photogravure, a screen is used to "etch" the lines
into the plate, these etched recesses (seen as dots of equal size) receive the ink, as above.
Characteristics: In deeply recessed (cut) plates, the resulting stamp shows raised ink, which can
be felt by rubbing one's fingernail across the surface. On a gummed mint stamp, indentations can
be perceived on the backside.
Any carelessness in printing may result in smudged ink, especially along the edges.
2. Names: gravure, photo-gravure (abbrev. photo)
Process. Rather than starting with a design engraved on a metal plate, the design is created on a
medium (paper), photographed, and transferred to a metal plate via a screen, through which the etching occurs.
Characteristics. In Photogravure, the proudness of the ink on the inked surface is less than in
intaglio, and the indentations on the back of the paper are less or not present at all. The design
has been etched onto the plate in the form of uniform dots. The spread of ink may be uneven as a
chemical wash is not used (as in engraving) but some form of a blade.
Relief or typography
3. Names: Relief, letterpress, typography.
Process: paper is pressed into contact only with the inked printing surface. The image on the
plate is produced in the same way, but as a negative design, i.e., the design is produced by cutting
away material, and the remaining uncut material represents the design. Ink is applied to the
surface, not into the recesses, and the paper picks up the ink from the surface, not from the (un
inked) recesses. Basic examples are designs cut from wood, cork, all producing "negative"
images, i.e., the design appears in white against a colored background. The next development is
printing from raised type, as newspapers once were produced from a plate of raised letters
(typesetting). Later, plates produced by electrotyping which presses down the areas to be un
inked, leaving raised the areas to receive the ink. Stereotyping is another method to produce the
same result. Plates may be metal or even rubber.
Characteristics. In line relief, a flat impression with evenness of ink except sometimes along
edges. Shading is done with lines and dots drawn in.
4. Name: photo-relief or half-tone printing .
Process: a screen is used to etch the plate, but with a screen of uneven dots. Such screening is
called half-tone screening. The dots are evenly spaced, but because the amount of ink is usually
different in each dot, the effect is of greater and lesser degrees of white and color and uneven
spread of shading.
Characteristics: A design with gradual transitions from dark to light. The dots may be evident (as
in newspaper photographs) or barely perceptible unless seen through a magnifying lens,
depending on the fineness of the screen.
5. Names: lithography (abbrev. Litho), offset-lithography (abbrev. offset), plano-graphic printing.
Process: paper is pressed is pressed into contact with the un-inked and inked surfaces of the
plate. The plate has been chemically treated so that the design is applied directly onto the plate or
stone, by hand, with a material that accepts ink, while the rest of the surface has been treated to
repel the ink. The result is a positive image.
Characteristics: even, flat designs. clean edges, clean impressions, intensity of color and shading.
Cross-hatching is often used to create shading.
6. Names: photo-lithography, offset-lithography (abbrev. offset).
Process: a half-tone screen can be used to create an impression of variations of tone or shading.
Offset-lithography merely means that rather than applying paper directly onto the plate, the
design has been printed on a coated cylinder to which the paper is then applied.
Characteristics: the resulting dots will be in linear formation (unlike photo-gravure). There are
no real "half-tones" (i.e., a dot divided into 4 segments), but even dark or clear spaces.
These terms should apply to the final printing process. To produce a final plate, one often begins
with an engraving, which is then photographed, which is used to transfer the image onto a glass
plate, and thence to a stone (or its equivalent) to print via lithography, or to be etched on a relief