Picking a white ink is a simple matter when you only print on one type of fabric
By Rick Davis
All garment screen printers want magic in a can—a white ink that always works perfectly on every type of apparel. Unfortunately, this mystical product does not exist. No ink formulation contains every desirable performance characteristic. That means garment screen printers must make concessions and plan carefully.
Small and medium shops usually get by with a couple of white inks. They focus on the types of fabrics on which they print most often and keep the appropriate inks on hand. Repetition alone enables these printers to master the use of a few white inks quickly. However, production managers in larger operations face the challenge of selecting specialty white inks for more challenging fabrics, such as polyesters and high-elongation materials.
I recently encountered some interesting strategies at two large garment-printing facilities. The first kept three or four different white inks on hand but printed 100%-cotton garments exclusively. Having more white formulations in house than necessary causes confusion. The other shop standardized to one white ink—a bleed-resistant formulation—that usually works across the board. Most of this shop’s work is on 100% cotton, which makes a bleed-resistant white an odd choice.
Almost any high-opacity white formulated for cotton would suffice. A bleed-resistant is only required for the occasional 50/50 blend making its way through the facility. This company rarely prints on 50/50 apparel but uses a bleed-resistant white because the production manager favors its opacity and flashing characteristics. However, the ghosting issues that arise after the goods are shipped might convince the manager to look at other inks.
The search for an all-in-one white ink is a waste of time, and stockpiling lots of different white inks is a waste of resources. Instead, concentrate on making sensible choices based on important ink characteristics.
Opacity is a relative term when it comes to white plastisols. Dozens of white inks are available, each offering a certain amount of opacity. Generally speaking, the higher the opacity, the better the performance will be in a wide range of conditions. Conversely, the lower the opacity, the more the control over process variables becomes critical. Keep in mind that variables such as screen tension, off-contact distance, and squeegee speed, pressure, durometer, and angle all come into play regardless of which white plastisol you select.
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