Aluminum is one of the most versatile and adaptable materials available for industrial use. It’s not an exaggeration to say that the commercialization of this amazing metal has transformed our society and unlocked an unprecedented level of technological and industrial progress. This includes the rapid developments that are happening in the area of offset lithography thanks to the use of lithographic plates and sheets made from aluminum alloys.
Manufacturers understand that material selection is integral to the success of your business. Everyone is searching for the most durable and effective materials at a reasonable price point. More and more often this search is leading people to turn to aluminum. At Clinton Aluminum, the Midwest’s leading supplier of aluminum plate and sheet, we strive to not only supply you with the perfect material for the job, but to be true partners to our customers at every step of the supply chain.
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Lithography has a long history
You might say the origins of lithography date all the way back to Ancient Greece. This is because the word itself is a combination of the Greek word for lithos, which means stone, and graphein, which means to write. It literally means to write on stone. What we think of as lithography actually dates back to the late 18th century, when it was invented by Alois Senefelder to be a cheaper method to reproduce printed text or illustrations onto paper using a stone (later metal) plate.
In early lithography, an image was drawn using oil, fat or wax onto a flat limestone plate. When the surface was treated with a special mixture that included acid and gum Arabic, any part of the limestone plate that was not protected by the oil used in the sketching of the image was etched or worn away, leaving the positive portion of the stone unharmed.
The next step was to add water to the stone, which would settle into the etched areas. An oil-based ink was then applied that would adhere to the positive portion of the original drawing. The plate is then pressed onto a sheet of paper to create the final print. It’s important to note that the illustration or text that is applied to the lithograph must be a mirror image of the final print. The traditional practice is so effective that it is still in use today, though it has been replaced with more modern techniques.
How does modern lithography work?
The biggest development in lithographic technique was when metal began to replace stone as the desired lithograph material. Many different materials have been used over the last century, but aluminum has proven to be a reliable and cost-effective option.
Lithography has transformed printing. Today most types of printed mass media, including newspapers, books and posters, are produced using what is known as offset lithography. This process uses a type of photography in which the printing plate is covered with a photosensitive emulsion. For the emulsion to work, the surface of the plate must have a brushed or roughened texture. Next, a photographic negative of the finished image or text is pressed against the emulsion and ultraviolet light is directed at the surface. The negative image is thus printed onto the surface of the plate.
The plate then gets attached to a cylinder on the printing press. Water is applied, just as with traditional lithography, which is repelled by the emulsion area. A special type of hydrophobic ink is then introduced to the process. Modern printing presses are complicated machines that work very quickly, employing a rubber blanket that removes the water but retains the ink and transfers it to the paper using uniform pressure. All of this is happening at rapid speed.
What type of aluminum alloy is used in lithography?
Aluminum is ideal for use as lithographic plate because it is lightweight, flexible and easily recyclable. The formability of aluminum makes it easy to give the plates or sheets the necessary surface roughness that is needed for the emulsion techniques.
Known as litho stock, the typical alloy used most often is 1050 grade aluminum. 1050 aluminum alloy is part of the commercially pure wrought family that forms the 1xxx series of alloys. It normally gets formed through an extrusion or rolling process, usually the latter when creating lithographic sheets or plate.
In addition to the printing industry, 1050 is commonly found in electrical and chemical applications due to its high electrical conductivity, corrosion resistance and workability. It is often used for heat sinks due to its excellent thermal conductivity.
1020 aluminum alloy is also being used in modern lithography as it has greater resistance properties, making it suitable for longer print runs.
Another benefit in using aluminum for your lithographic plates is that it can easily be recycled. Printers will sometimes need to go through hundreds of sheets a day to fulfill their output needs; having a material like aluminum that can be reused not only makes environmental sense but helps to reduce costs as well. It is necessary to wash off the excess ink as well as remove any tags that were used to identify the sheet prior to recycling.
Your Technical Resources Partner
Many manufacturers and printers have concluded that aluminum makes financial sense due to its flexibility and high performance. Working with a good supplier is about more than just picking out the right material. You need to have the confidence that every inch of aluminum plate and sheet meets the same rigid requirements. Any lapse in quality can have a drastic effect on your results.
At Clinton Aluminum, our mission is to always live up to the high standards our customers expect from us. That’s why we are committed to working with our customers at every step of the procurement process. Contact one of our friendly customer service representatives today to learn more about what aluminum alloy might be right for you.
