Printer ink is one of those things that one doesn’t think about until it runs out, then all hell breaks loose. But how do the texts and images from our computers transfer onto paper? What is the ink that we see on daily basis made of? The best way to describe this is a breakdown of the ink’s ingredients and the process.
Dyes and pigments
Dyes are colorants that fully dissolve in liquid, mainly water or glycol in printer ink. Dye-based ink offers a wider variety of colors than pigment-based ink. Furthermore, the color of dye-based ink is far richer and more vibrant. An additional advantage is that it is more affordable. Its disadvantage is that, since it is easily dissolved in liquid, it has a very weak fade resistance; exposure to light, heat, or water will make the ink bleed and fade away with time.
To form pigment-based ink, these tiny insoluble solid particles are suspended in the carrier fluid. Unlike its rival, pigment-based ink is highly resistant to heat, light, and water. This makes it the most popular choice for offices and schools. The downside, however, is that it is more expensive; it also has less color depth and variation.
They are added to the ink to bind its components together and to the paper or any other printing surface. They do so by forming a distinct film with the ink. This binding action also improves the rheology and mechanical properties of the ink. Some resins, like ketones, alkyds, acrylics, and formaldehyde, are used together to create a highly-resistant glossy printing surface.
They are substances that act as a dispersing agent, meaning that they are used to disperse small particles of one substance in another. In the printer industry, they are used to assist the flow of the ink and its transfer onto the printing surface. They decrease the mechanical energy needed for grinding the pigment particles, slowing them down and stabilizing them. This is accomplished by suspending surfactants and polymers in a solvent. This prevents the pigment particles from setting or clumping.
Varnish is a clear liquid that makes a film of glossy protection. It is considered to be the base of the ink. Each type of ink has its type of varnish. It is usually linseed or soybean oil, or a heavy petroleum distillate used as the solvent, combined with pigments to create ink that dries by evaporation. Varnish and carbon black make black ink. Varnish and titanium dioxide make white ink. Color pigments are made of salts and multi-iring nitrogen-containing compounds or dyes such as peacock blue, yellow lak, diarylide orange, and phthalocyanine green. Varnish is mixed in with these pigments to formulate colored ink.
Additives are essential to make the ink we know today. Examples of additives are humectants, defoamers, biocides, bacteriostats, antioxidants, thickeners, alkalies, wetting agents, and waxes. Humectants are substances that keep moisture without an oily feeling and prevent evaporation; hence, they slow the aging of the ink and help it last longer.
Defoamers, on the other hand, help prevent or modulate the formation of bubbles or foam in the ink. Biocides and bacteriostats prevent bacterial and fungal growth and elongate the ink’s shelf life. Antioxidants act as an anti-aging agent.
Thickeners are used to control the application of the ink, Alkalies, on the other hand, are imperative in controlling the ink’s solubility and viscosity. Wetting agents are utilized to control the printing surface properties. Finally, waxes provide durability and rub-off resistance.
The process and the ingredients of the mixture may vary depending on the company and the printing surface. However, the basic process goes as follows:
- Pigment (mainly cyan, magenta, yellow, or black) is mixed into varnish
- The mixture is weighed into a pot and then put into a mixer
- The mixture is heated by mixing to become much thinner
- The mixture turns into a liquid
- The grinding and/or dispersion process is done by a machine called three roller mill
- It consists of three large steel rollers running in opposite directions and speeds to homogenize pigment particles thus providing a glossy lump-free finish
- Quality tests are done at this point
- Once its quality is approved, the mixture is back to the mixer
- Additives such as waxes, humectants, and defoamers are added
- More tests are done to ensure maximum quality
- The ink is canned over a three roller mill to maximize gloss and take out the air
Finally, we now understand the full breakdown of the process of creating ink. We can also now full identify any element that is used in making printer ink whether dyes or pigments to give the ink its color, resin to hold everything together, varnish to provide that glossy protecting or finally any other type of additives.