Ink is created from a variety of dyes and oils that come from several sources that are formulated to suit a specific purpose. For instance, black ink is made from carbon black exclusively for use as a dye, but other pigments are used to produce virtually every color of the rainbow that you find in printing nowadays. Some inks include resins to help keep the pigments bound together and to make them suitable for printing on specific surfaces.
One crucial part of the process for making black ink is wetting the carbon black during the premixing process. After that, any pigment that is necessary is added to the oil to create the desired viscosity, which affects how the fluid flows in the printing process. The goal of this process is to create inks that provide the ideal dispersion onto whatever material is being printed on. There are several configurations performed by machines that can alter the mixing and flow options for printing.
Premixing is necessary to ensure no trapped air is left in the ink formulation. High-speed dispersers are used to premix inks. Once the premix is taken through the disperser, it is mixed more and then additional oil and/or resin is added to achieve the ideal milling viscosity, also known as the mill base. The ink pigment is run through a chamber that creates smaller particle sizes, which is determined by the dispersion requirements.
After that, the ink pigment endures a variety of filtration steps used to eliminate large particulates in case any metal is left behind from the milling process. The tiniest of metal pieces can be filtered through an electromagnetic filter designed to grab metal fragments.
Once all metal fragments are eliminated, the pigment is pumped into a letdown tank to make final adjustments to the ink. This is done to meet the needs of customers with specific printing needs.
Color inks are processed differently than black inks. Flushed pigments are used instead of dry pigments like carbon black.
The final stage of manufacturing color pigments involves filtering the water-based mixture that is then put in a concentrated form called a presscake. The presscake is mixed with an oil-based varnish to extract extraneous water from the pigment. That process uses a heating and vacuuming action.
Why do they flush pigments? They put color pigments through a flushing process so that the pigments will be dispersed evenly throughout the ink medium. Flushing also helps manufacturers avoid expending the high-energy use that comes from using milling machines. The raw materials like oils, extenders, and varnishes must be thoroughly mixed at a consistent temperature to prevent pigment deterioration in the process.
After the mixing is done, the ink is tested for quality to ensure it meets all the requirements. Then it goes through a series of filtration processes to remove oversized particles just like what is done for black ink that removes metal particles. Sometimes oversized particles stay behind due to the processes the color ink goes through, and those particles must be removed. After that final process is complete, the ink is shipped to its respective customers for their use.
These are the basics steps taken in the manufacturing of black and color ink. While there are other technologies some manufacturers use in addition to these, the basics remain intact in the manufacturing of ink.
Article by Needham Ink