The most important part of ink is the colour. Printing ink consists of the color pigment and the vehicle that carries it, which is varnish. The process of making ink entails mixing these two components together until they become fit for printers.
The varnish has some viscous parts, while other parts are extremely thin. These two are put in a pot and under a mixer. They are heated up by the mixing action until they become thin enough; way thinner than they would be at room temperature. When the varnish is equally thin at all points, the color pigment is added in to the pot. The color pigment is usually in powder form hence combining it with the varnish is necessary in order to make it liquid. These two components are mixed until the color diffuses properly in to the varnish.
The second part entails grinding, which in real sense is dispersion. The dispersion process entails breaking the pigment in to fine particles. When the color powder is mixed with the varnish, some parts form lumps. This process uses two machines; a bead mill and a three-roller mill. The bead mill has several steel beads that break the colour particles away from the lump. However, this mill creates a rough end result. The three-roller mill is then used to create a smooth end product. This mill has three steel rollers that move in opposite directions. This movement pulls the rough particles apart to bring out the gloss and the rich color.
When the ink is smooth enough, it is taken through quality control tests. These tests are meant to ensure that the ink produced is the same through one batch to the next. The first test is a grind test. The ink is laid on a steel block and pressed. It should reveal a smooth line that shows all the color pigment was broken down perfectly. The second test is the bleach test. Some ink is added in to white opaque bleach and mixed to check the color strength. The bleach helps the computer check whether the color has been developed appropriately. Another test is done to ensure the ink is sticky enough for printing.
In the final process, the ink is put in a pot and some extra ingredients are added in to it. These include waxes which create rub resistance and dryers that enable the ink to turn in to a solid film when used during printing. The ink is then canned by a three-roller mill that takes out air and creates more gloss.
The final product is a glossy ink that has rub resistance, set speed and is sticky enough for printing.
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