In lithography the printing and non-printing elements are on the very same level. The sophistication of the printing spots is the fact that they are ink-accepting, whereas the non-printing plate areas are ink-repellent.
This effect is created by physical, inter facial surface phenomena.
Lithographic printing is generally subdivided to:
- Stone lithography (direct printing method utilizing a stone printing plate),
- Collotype (direct printing technique),
- Offset printing (indirect printing process), and
- Di-litho (direct printing process with offset printing plate).
Lithography was created by Alois Senefelder in 1796. The image to be printed was drawn on the stone with the use of a special ink. The stone was dampened right before it was up, after which the non-image zones of the stone surface have not take on ink.
Collotype is a second lithography technology. A light-sensitive level of gelatin is exposed on a glass base over the negative and then developed. Parts having diverse swelling properties in relation to water are generated. After the printing plate has been moistened, differentiated color shade absorption features are produced. Just like stone lithography, collotype is only applied to artistic printed products or services (with very short print runs).
Offset printing is the greatest lithographic technology. It is an indirect lithographic technique, a situation where the ink is first transferred from the printing plate into a adaptable midpoint carrier – the blanket – and then onto the substrate.
To get an ink-repellent effect on the printing plate (totally different interaction of printing plate surface and ink), there are two frequently used solutions :
- Conventional offset printing technology: Dampening of the printing plate with dampening solution (water along with additives). The dampening solution is applied to the plate in a very thin film by dampening rollers. The non-image places of the plate are hydrophobic, and that is, water-receptive additionally the ink accepting surfaces are oleophilic, and are just about totally unreceptive to water. The film of dampening solution stops the transfer of ink. Because this technology is by far almost certainly the most widespread, the repellent outcome among the ink and dampening solution is regularly always associated with “offset printing.” For this reason, inking and dampening units are required for “offset printing.”
-Waterless offset printing technology: The printing plate surface is mainly ink-repellent, for instance, due to an appropriate layer of silicone. The ink-receptive base zone is exposed by the deliberate interruption of the layer of silicone (just about 2 microns thick). This techniques is named “waterless offset” (very often as “dry offset”). Suitable printing plates and special inks need to be used for each of these technologies.
The di-litho technology, a lithographic technology in which the printing plate prints straight onto the printing substrate, was uniquely created for newspaper printing. The benefit from this technology was that conventional letterpress rotary printing presses could be used. The printing units of these presses were actually modified by the installing of a dampening unit. Printing was done with conventional printing plates, nevertheless a special coating needed to be applied to them because of the very high tension because of the direct contact with the paper and the high stability with the full print run necessary in newspaper printing. This technology only played short-time role. Once new investment was made in newspaper printing firms, this technical solution was altered by web offset presses, which print onto the substrate via a blanket cylinder.
Advantages
- persistently high-image quality.
- much quicker and easier production of printing plates.
- extended life of printing plates since they primarily come in contact with the printing blanket, which happens to be much softer and less abrasive than paper
- cheapest production on excellent quality images in large quantities.
Disadvantages
- expensive cost for small quantities
- the image quality is excellent for commercial purpose yet not as good as rotogravure or photogravure printing.
This effect is created by physical, inter facial surface phenomena.
Lithographic printing is generally subdivided to:
- Stone lithography (direct printing method utilizing a stone printing plate),
- Collotype (direct printing technique),
- Offset printing (indirect printing process), and
- Di-litho (direct printing process with offset printing plate).
Lithography was created by Alois Senefelder in 1796. The image to be printed was drawn on the stone with the use of a special ink. The stone was dampened right before it was up, after which the non-image zones of the stone surface have not take on ink.
Collotype is a second lithography technology. A light-sensitive level of gelatin is exposed on a glass base over the negative and then developed. Parts having diverse swelling properties in relation to water are generated. After the printing plate has been moistened, differentiated color shade absorption features are produced. Just like stone lithography, collotype is only applied to artistic printed products or services (with very short print runs).
Offset printing is the greatest lithographic technology. It is an indirect lithographic technique, a situation where the ink is first transferred from the printing plate into a adaptable midpoint carrier – the blanket – and then onto the substrate.
To get an ink-repellent effect on the printing plate (totally different interaction of printing plate surface and ink), there are two frequently used solutions :
- Conventional offset printing technology: Dampening of the printing plate with dampening solution (water along with additives). The dampening solution is applied to the plate in a very thin film by dampening rollers. The non-image places of the plate are hydrophobic, and that is, water-receptive additionally the ink accepting surfaces are oleophilic, and are just about totally unreceptive to water. The film of dampening solution stops the transfer of ink. Because this technology is by far almost certainly the most widespread, the repellent outcome among the ink and dampening solution is regularly always associated with “offset printing.” For this reason, inking and dampening units are required for “offset printing.”
-Waterless offset printing technology: The printing plate surface is mainly ink-repellent, for instance, due to an appropriate layer of silicone. The ink-receptive base zone is exposed by the deliberate interruption of the layer of silicone (just about 2 microns thick). This techniques is named “waterless offset” (very often as “dry offset”). Suitable printing plates and special inks need to be used for each of these technologies.
Advantages
- persistently high-image quality.
- much quicker and easier production of printing plates.
- extended life of printing plates since they primarily come in contact with the printing blanket, which happens to be much softer and less abrasive than paper
- cheapest production on excellent quality images in large quantities.
Disadvantages
- expensive cost for small quantities
- the image quality is excellent for commercial purpose yet not as good as rotogravure or photogravure printing.
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