The search for sustainability pushes many screen printers to rethink their production methods and consumables choices. Read on to learn why water-based inks are a viable solution and discover how you can use the latest formulations to produce unique effects on garments.
By Ed Branigan
Ink manufacturers have recently taken steps to increase the solids content in water-based inks in hopes of making them friendlier for use on dark shirts. This trend is especially evident over the past 10 to 15 years. The initial results gave excellent opacity and color fastness, but did not increase retention times in the screen. Some of these inks were even harder to manage and dried up even faster. The trade-off was still a tough one: cheaper inks, somewhat more environmentally friendly, great color and opacity on darks, easy to reduce for use on lights (which also saves on cost), but difficult to maintain on long production runs. Again, the use of retarders could help, but the problem still remained, and water-based inks continued to be seen as the demon of the print shop— although a somewhat necessary demon.
Demands for development
The push in recent years towards sustainability and the increasing awareness among end users and consumers concerning the environmental impact of products and lifestyles has driven the development of greener inks in screen printing. Along with PVC-free plastisols, the spotlight is again on water-based inks. Most of the major manufacturers now promote a version of each type of ink.
Huge leaps have been made in recent years in water-based-ink technology. With the introduction of newer wetting agents and emulsifiers, the old scourge of ink drying in the screen has been greatly diminished. Some of these newer inks now can be left in the screen four to five times longer without clogging or drying. Inks that lose moisture from evaporation due to the heat from dryers and extreme climate can be re-emulsified and re-used. Shelf life has been greatly increased, with some products now lasting up to two years if stored under the correct conditions.
Application ranges for some of these inks have opened up to rival those of plastisols. Opaque whites that allow solid underbase printing on dark shirts, coupled with the ability to print through high mesh counts—a practice that was unheard of for traditional water-based printing—has given rise to possibilities both new and exciting. One example is printing halftones onto dark shirts using the same line weight and mesh as plastisols (Figure 1). Printers also can use newly developed modifiers and emulsifying agents to very effectively manage drying time in the screen.
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