This is a term that describes a printing process in which the image area and the non-image area coexist on the same plane, as opposed to letterpress or gravure. Lithographic printing is based on the premise that oil and water do not come together (although a minimal amount of mixing is necessary for lithography to work); The image area of a lithographic printing plate is adhered with a greasy oil-based ink, while the non-image areas will attract water, mutual chemical repulsion, keeping the two regions separate.
The word lithography (whose origin is the Greek words lithos meaning “stone” and spelling meaning “writing”) originally refer to the use of special stones (a variety of calcium carbonate) on which the lithographic impression was made at the beginning. . At present, lithography refers to the use of aluminum plates that have been replaced by lithographic stones, but well, we will see this later in the article for now let’s focus on that historical moment when lithography was invented.
Alois Senefelder was the inventor of lithography in 1798. From its modest beginnings this printing process became one of the largest industries within the USA, reaching the third place in the ranking of industrial prosperity within this country.
Over the course of several years or to be more detailed more than a century and a half, lithography was a minority segment within the printing industry in the United States as it was used primarily by artists to reproduce their works. But in the late 1800s and throughout the twentieth century great technological advances were made that improved the lithographic process, making it the most important and popular.
The history of lithography to occur in the USA is shown in the historical records in this country from four main stages:
- The invention and early use of the process
- Introducing photography to the process
- The addition of offset lithography to the process
- The lithographic plate revolution
What is it for
Lithography has long been one of the most widely implemented forms of printing throughout the world, due to its importance in reproduction at an editorial, artistic and graphic level. With this if we ask ourselves and all these despite their contribution in the end, what is it for? the crude and hard answer would be large-scale reproduction saving costs and time, it was not the same that an artist tried to reproduce his works 10, 20, 30 times or more before lithography to increase the coverage of his work, therefore thanks to This invention the artists were able to reproduce their art with greater speed, an idea that the great printing industry would take up again to take it to another market beyond the artistic one as mentioned in the previous paragraph, but that is already another matter;)
Next I will list the essential materials to carry out the lithographic printing process.
Basically the rollers are the tool that printers need for the inking of the matrix, usually their material is leather and rubber with two handles at each end, lithographic rollers are generally larger since with this only one is given pass.
Lithographic pencil or grease pencil
This is the implement that you will use to draw on the stone or micro-etched aluminum, among others, it is basically the element with which you will make the design and retain the ink for the printing process on the paper.
Also known as grease ink, it is the one that adheres to the design made with the lithographic pencil and is applied with the roller after having applied the nitric acid and the gum arabic.
This resource applies to a more technical lithographic process and is basically the machinery that would press the paper so that the lithographic printing is cleaner and more professional. In my case the lithographic press when I make an impression is my hand 🙂
Offset lithography is a type of lithographic printing in which the ink plate first transfers the image to a kind of rubber, and this then transfers the image to paper or other surface. Lithography groups together processes such as sheet metal offset lithography, web offset printing, direct lithography (also called Di-Litho) and waterless printing.
Offset lithography process
In the following system we are going to present how an offset lithography rotary works.
The iron is ready. It has parts that repel water and parts that adhere it. The places that avoid the ink will be the ones that take it.
The plate is placed on the cylinder technically known as the plate holder and in this way the paper is attached to the system.
When the system starts up, the fountain cylinders print the areas of the plate that must repel ink with a special solution. The areas to be printed are ready to repel water and remain unmoistened.
The plate rotates until it reaches the inking cylinders, which put a greasy ink on the plate. As the water does not allow it to adhere to the ink, the plate only picks up ink where it is going to be printed, that is, in the areas that are not wet.
The plate, already inked, rotates and comes into contact with the cylinder, whose rubber surface is the blanket. The image is printed upside down on the cylinder, which rotates contrary to the plate.
The paper passes between the rubber cylinder and the impression cylinder that serves to press the paper against the blanket.The paper receives the ink image of the blanket, which already passes through it in the correct way and that is to say no longer in an inverted way, leaving the art already printed as it should be.
Here is a video about the offset printing process of a newspaper.
Chromolithography is a unique and singular procedure for making impressions implementing different types of colors. This type of color lithographic printing came from the lithography process and bringing together all types of lithography using the color system.
Lithography example using limestone
For this type of printing, a limestone is handled on which the image to be printed is illustrated with a greasy material, either using a brush or a pencil. This method takes advantage of the incompatibility of grease or oily components and water, since wetting the stone will only retain the printing ink in the areas illustrated above.