Water-based pigmented inks, water-based dye inks, water-based latex or resin inks, true solvent, mild-/eco-solvent inks and UV-curable inks—which should I chose? How long will they last? The key here is the system and not the ink type. First, there are the pigments. The ones chosen are selected for different reasons by each vendor. If an ink set is primarily for indoor use, very bright pigments are selected since “color sells.” The pigments might not be the most lightfast, but that might not be needed if the prints are not expected to be exposed to intense UV light.
 
When used outdoors in demanding applications prints will show UV fading irrespective of whether they are water-based, solvent based or UV-cured. If they are protected by a protective layer with UV absorbers they will last longer. Yellow is the most difficult to protect, and bright yellows are not very light fast. If you want lightfast yellow then pick a greenish yellow with less brightness so you have much better lightfastness.
 
The tradeoff is in the reds. They are not as good with lightfast yellows. Second is the substrate/binder combination and how it bonds together. There is very little binder with traditional water-based inks. There is just enough to hold the pigments to the coating on the media. The media must provide the durability. For more than just short-term outdoor applications, a protective layer is required.
 
With Latex/resin, UV-curable and solvent and mild-solvent inks there is significant binder present. With UV-curable you have the most binder since all of the fluid becomes part of the cured image. One might think that because there is more binder with UV-curable inks that they will be more durable. Not necessarily.
 
Along with the binder, one must consider the adhesion of the binder/pigment combination to the substrate. A strong durable binder is no good if it doesn’t adhere to the substrate.
Perhaps the best adhesion is with strong solvent inks. They have ingredients that smell bad, are not very people or environmentally friendly and need to be ventilated in your shop—but they bond really well, especially to vinyl. In addition, their binder is very durable. They were initially designed for vinyl billboard applications so were never intended for indoor use.
 
Mild solvents/eco-solvents are a compromise and generally do not perform as well. To make them people-friendly, they trade-off the aggressive solvent components for less aggressive solvents. UV inks frequently suffer from incomplete curing. If this occurs, then adhesion and outdoor durability will suffer. Black and yellow pigments absorb UV light very effectively and make it difficult to get a complete cure unless the printer is run slowly. With UV inks it is sometimes difficult to tell if the cure is complete so it can be a mixed bag.
 
SUMMARY

So my conclusion to how long will they last? Well, it just depends! There is no magic answer here. Only by arming yourself with the knowledge of what factors affect the durability of the print and the knowledge of how it is expected to be used can you determine what to expect from your print. Don’t be afraid to use manufacturer type warrantees as a guide on what combinations of materials will provide you with the solution your customer needs.