House of Questa – Distinguishing stamps from sheets of 5 and sheets of 10
The House of Questa printed all stamps in gravure on non-fluorescent paper with a yellow-fluorescing phosphor bar at left. It, however, is possible to distinguish between the stamps from sheets of five and those from sheets of ten stamps.
The stamps from the sheets of five stamps were printed from left to right. Those from the sheets of ten stamps were printed from bottom to top, or upright. The sheets were perforated with a rotary perforator. This had pins that lifted the paper from the printed side of the stamp and a rotating knife that sheared off the raised paper. This process leaves paper residue, or 'swarf' on the gummed side above or below the perforations, depending on the direction in which the paper passed through the perforator.
Stamps printed from left to right pass through the perforator with the right side first. Seen from the back, the swarf is visible to the right of the perforations on the lefthand side, that is the righthand side when viewed face up. Stamps printed upright will have the swarf above the bottom perforations as the stamp passes through the perforator from bottom to top.'Nikkels' permanent series printed by the House of Questa 'swarf'
The direction of printing, also, can be determined from the directional flow of the ink droplets that make up the printed image. The (photo)gravure process uses a screen of small recesses that make up the image. The recesses hold ink that the press transfers onto the paper. The movement of the paper through the press causes a directional flow of the ink when it is transferred from the recesses onto the paper.
If the printing is sideways right as for the sheetlets of five stamps printed by the house of Questa, the ink droplets will flow from left to right. If it is upright as for the sheetlets of ten stamps, the ink droplets will flow from bottom to top.
Below images show the second 'N' at the bottom of 2 eurocent stamps. The top image shows the droplets on the right side of the vertical legs of the 'N' point right. This a stamp from a sheet of five stamps. The bottom image shows the same 'N' of a stamp from a sheet of ten stamps. For this stamp, the direction of printing is not as easy to determine as for the lefthand stamp. However, the droplets at the top of the left leg show the flow of ink towards the top of the stamp. This stamp was printed upright. 'Nikkels' permanent series (Questa) direction of printing for the 2 eurocent stamps
Looking closer at the screen of the letter 'N,' it is clear this is denser for the top stamp than for the bottom stamp. The two vertical legs show alternate rows of six and seven dots. On the bottom stamp there are eight dots.
Below are the corresponding images for the 10 eurocent stamps. The direction of printing is easier to determine for these two stamps. The remarks about the screen of the printing, also, is valid for this value.
\'Nikkels' permanent series (Questa) direction of printing for the 10 eurocent stamps
The House of Questa only printed the 5 eurocent stamps in sheets of five stamps. These have a sideways right direction of printing.