There are several different types of inks used in industrial digital printing. Each of these has slightly different characteristics, and understanding the differences between each one can make a difference in your costs and the quality of your printing.
Ink is the core of any inkjet printing system. Essentially, ink is simply a pigment that is suspended in a liquid that is carried to the media to deliver and bind to the media’s surface to deliver an intended message, graphic or design.
Creating ink requires a cheap and sustainable carrier. Water is by far the best choice, but once an ink with a water base is delivered, the water needs to be dried; otherwise the water tends to soak into any uncoated media. This means that any water-based ink can only print onto a coated media which can raise its cost.
Most aqueous inks are capable of producing extremely sharp images and most printer manufacturers have models that use up to twelve separate inks to create excellent photos and posters. Because the inks are water-based, the images are usually considered for indoor use only, however if they are properly sealed with the right lamination, they can also be used outdoors.
Instead of water, solvent inks use a solvent that serves as both a carrier for the ink pigment to the media and it helps to slightly melt the surface allowing the ink colorants to penetrate beneath the softened surface effectively biting into the media itself. Then, once the solvent evaporates, the colorants are permanently etched into the media creating an image that withstands scratching and weathering.
As the solvent evaporates, however, it emits volatile organic compounds that can cause respiratory problems in humans and animals. This necessitates removal by special ventilation methods to be eco-friendly according to government regulations.
Several companies have developed latex inks that use a polymer resin that encapsulates the ink pigments to help them bond to the substrate. Water is initially used as a carrier making the process environmentally friendly. However, to cure the ink requires considerable energy to remove the excess water content.
The primary advantage of latex ink is that the print is dried prior to when the substrate is received by the take-up roll. This allows the prints to be laminated immediately after printing. Latex inks are scratch-resistant, even without lamination, and can be used outdoors making them an excellent substitute for solvent inks.
Other types of inks
Several other types of inks are used today including UV-curable inks, hybrid, pigment and dye-based inks that are used in most home printers. However, they tend to fade easily and not work well with water-resistant or glossy surfaces.
There are multitudes of different substrates that need to be printed on and making the right choice of ink will determine how acceptable the final results will be. Making the wrong choice will result in a disappointing outcome, but making the right choice can make all the difference in the world.
This article was contributed by Needham Ink