The first stamps of Mexico were engraved by A. Villegas, who produced all the plates used for all the printings.
The following is an attempt to describe the process of line engraving. This method is also known as intaglio.
At first a designer creates a drawing, for example, which serves as the model for the engraver. Nowadays this model could be a photograph, of course, but photography was barely invented in 1856.
One or more engravers start the production by engraving a master die. This die is usually made of soft steel, and is worked on with hard steel tools called gravers or burins. Most often the design is engraved in reverse, as a mirror image of the original design. The central design, called the vignette, was usually the last part to be done. The denomination tablet at the bottom of the first Mexican issue was left blank on this master die, or at least not finished, as will be explained.
When the master die was completed, or nearly completed, a print could be taken from the still soft steel. These prints are referred to as die prints, or proof prints, and they were used to get the final acceptance for the engraving. Perhaps minor flaws and errors were discovered at this point, and the master was touched up, or retouched as it is also called. This, however, does not seem to be the case in Mexico - the result was perfect the first time!
Once the master die was approved, heating and rapid cooling in oil or some other liquid hardened it. Once hardened, the die cannot be worked on with engraving tools, since it becomes too brittle, and would only chip or break.
The hardened master die is then transferred, using high pressure, to another die, made of soft steel. This die, with the relief looking like the finished stamp, was then outfitted with the appropriate denomination in the lower tablet. The reason for not saying "was engraved", is because we don't know how the denomination was added. It could have been engraved, but it could also have been stamped in, or even etched. We just don't know at this point. At least five dies would have been made, one for each denomination.
This die is most often made as a roll - either as one or more transfers to a round steel bar, or as a plate, which is then bent into a curved shape. The latter solution seems to have been used in Mexico, since we can see traces of nail heads on the stamps. As with the master die, the transfer die has to be hardened before it can be used. This single finished die was used to make the 60, and later 190 or 200, transfers to the actual printing plate. Perhaps not surprising, this die is named a transfer die. The person doing the transfers to the plates is called a siderographer.
The printing plate is now made by rocking, or rolling, the transfer die into it, as many times as there are stamps on the plate. This process requires quite a lot of pressure, causing the printing plate to bulge up, similar to a person lying down on a bed. Also, as the die is moving out of the softer plate, it lifts some of the material, referred to as burrs. Burnishing, or polishing, the plate with a hard, smooth stone tool, made of agate, remedy both these effects. The colored marks seen on the sides of many of these stamps are the result of the filing down, and later burnishing, of the bulges in the plate. Not surprisingly perhaps, these marks are called burnishing marks. However, another theory has been offered by Turnburke: the marks were left by the transfer die. It is thought that the edges of the master die were filed down a bit, thus causing slightly raised edges on the transfer dies. These raised edges would then appear as shallow depressions on the printing plate. We know they must be shallow since they wear away rather quickly.
The transfer die may be damaged at any stage of this operation.
Once a plate is laid out, a print is usually taken as a last check. This print is called a plate proof. If any errors or flaws are discovered, they may be corrected by hand, directly on the printing plate. In case of more severe problems, the process is a bit different. By hammering the printing plate from behind, the plate is raised a bit, and the position, which has to be corrected, can be filed away. After filing the position is burnished to make it smooth and even. Sometimes the whole design was removed, sometimes only parts of it. Once removed, a new transfer is made to the position in question - this is called a re-entry. If the design was not removed completely, we sometimes see a partial imprint of the erased position, looking like the design is doubled, or slightly offset, in certain places.
When a plate proof is finally approved, the printing plate is also hardened, just as the dies were.
|Denomination||Color||Number of plates|
All three plates for the medio real stamps were laid out as 6 columns of 10 stamps. So were the first two for all the other denominations. Plate III and IV for the un real were laid out as 20 columns of 10, and plate III for the dos reales was laid out as 19 columns of 10 stamps.
Only one plate was used for each of the 1856 issue of the cuatro and ocho reales stamps. Plate II for the cuatro reales was used to print the 1861 issue. Only reprints are known from the ocho reales plate II.
It is well worth noting that the stamps issued from April 18, 1861, in new colors and on colored paper, were printed from some of these same plates.
A note on framelines.
According to Turnburke, all the early (wide setting, with 60 subjects per plate) plates started out without a frameline. These lines were quickly added - Turnburke found that about 3% of medio real stamps from the edge of the sheet did not have framelines. Also, it is estimated that about half of all the stamps from the sheet edge have had their framelines cut away. Thus, not showing a frameline does not preclude a stamp from being from the sheet edge.
Plating therefore becomes important to accurately determine which plate a stamp originated from, since a stamp from the edge of the sheet may show no frameline even though it has one or more wide margins. The large plates, with narrow spacing, all had framelines from the very beginning.
In some cases it is possible to mistake a burnishing mark, or die mark, for a frameline.
A note on the plate material.
According to the Celis Cano catalog, the printing plates were made of brass. This is highly unlikely, since brass is too hard and brittle. For the early plates it is at least more likely that copper, if not steel, was used, since it is softer, and therefore easier to work with. Copper plates have been used all over the world for printing for a long time. The later, and larger, plates were probably made from steel, a much more resilient material. Considering that over 2.3 million stamps, corresponding to over 120,000 sheets, of the dos reales were printed from plate III, and that the impressions produced in the end were quite good, it must be assumed that steel was used.