Printing is all about the process of putting ink on paper. In planning a job, it’s easy to spend a lot of time thinking about the paper without putting much thought into the ink. But understanding the ins and outs of ink and how it gets on the paper is important to a successful design.
First, it helps to understand a bit about offset lithography. This printing method is based on the basic principle that oil and water repel each other. Ink is oily, and the original lithographers printed pages by pressing images against the inked surface of a stone. Water was kept on the non-image area forcing the ink to stay in the image area. Modern lithographic plates work similarly. They have an ink-receptive coating, which is activated only in the imaged area. Although waterless techniques exist, most often water is used to prevent ink from getting into the non-image areas. Instead of pressing paper on a stone, modern presses transfer images from an inked plate to a rubber “blanket.” The plate doesn’t actually ever make contact with the paper, the blanket does. The image ‘‘offsets” from the plate to the blanket and again from the blanket to the paper.
Various inks are formulated differently for different purposes and equipment. When manufacturers make ink, they deal with four basic elements: pigments (the coloring), transfer agents (the solvents and resins that cause the ink to spread), varnishes (the additives that control glossiness), and drying additives. Different combinations of these elements determine the suitability of an ink for a particular project.
For example, you may have heard of “scuff-resistant” inks. These inks were specially formulated for the packaging industry to allow printed items to withstand more abuse during transit. Metallic inks are another special type of ink. They get their shine from real metals added to the ink base. Silver ink includes aluminum, gold ink has bronze or copper alloy and copper ink has copper. Because they contain actual metals, metallic inks can tarnish easily, so the ink is mixed up just before being used. Since metallic ink is laid down more thickly, these inks take longer to dry than standard four-color process inks. The thick ink coverage also makes metallic more prone to scratching or scuffs. We generally recommend putting an aqueous coating over heavy metallic ink usage to quicken the drying and minimize the scuffing.
If you want to use fluorescent colors in your designs, nothing reproduces fluorescent color as well as fluorescent inks. To produce their bright effect, these inks must be printed on white paper. However, like metallic inks, they are more opaque than four-color process inks, which can cause trapping issues. This type of ink also fades in brilliance over time. If you have a project that will be around for a long time, keep this limitation in mind.
Soy inks have gained popularity recently for environmental reasons. Most offset inks use petroleum-based oil as a solvent to dissolve the resins that carry the ink pigment. When the ink is run through the heat drying process, the solvents emit volatile organic compounds (VOCs). Soy inks contain soybean oil instead, resulting in lower VOC emissions. All of Action Graphics process inks are soy and vegetable-based inks ensuring that your printed projects are contributing to a healthier future for us all.
Even though the basic principles of lithography are simple, inks involve a lot of complex chemistry. If you have a project with special requirements, please contact us to discuss the best methods of producing the project. We will work with you to find the best solution – including custom ink mixes to ensure consistency – for your project.
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