Avoiding problems early on in your color separations will cascade down into gains at every step of the screen-printing process.FULL STORY
Screen Printing: Production
Demystifying White Ink
Screen printers have searched high and low for the perfect white ink. The truth is, good traditional screen printers can choose among a variety of white inks from each of the manufacturers, and each will work great if used for the appropriate purpose and under the right conditions.
If you’re using white ink that has gelled because you stored it in a hot shed during July, or if you’re using mesh that has no tension and printing with a 25-year-old squeegee, chances are your white won’t work right. However, if you understand the different types of white ink available, use them in the application for which they were intended and follow some fundamental printing techniques, you’ll be cranking out white-hot designs in no time.
What’s Your Function?
White ink manufacturers have developed a variety of formulas to meet specific needs. The following list of white inks describes the different offerings and provides criteria on when to use each type.
All-purpose white plastisol. Most ink suppliers sell multipurpose white plastisol that provides decent opacity on dark garments. You can use this formulation as a standalone spot color or an underbase print on dark shirts. You also can use it as a highlight color printed last in the color order for simulated-process designs on dark garments. Further, choose an all-purpose white to mix with other colors when you need to lighten them.
All-purpose white also works well as a spot or highlight color in designs on white T-shirts. Why use white ink on white garments? Because after the garment is washed several times, it starts to lose its new, bright-white look. The shirt’s brightness may fade, but the white ink in the design will remain crisp and vivid.
Athletic white. This formula provides high gloss with good elasticity and opacity for printing on athleticwear and team jerseys (see image). Though some printers prefer athletic white for all applications, it’s not always a good choice because it’s thicker and difficult to print through fine mesh counts. Plus, its glossy finish isn’t appropriate for all designs.
Fast-flashing white. This type of white ink is made with a resin that gels at a lower temperature than standard plastisol ink, therefore reducing flash time. To achieve the whitest print on dark garments, you should put down an underbase white, flash it and overprint colors and white on top (commonly referred to as a “print, flash, print” sequence). But flashing conventional, all-purpose white plastisol is time-consuming and can be tricky – which is where fast-flashing whites come into play. The quicker the underbase white flashes, or gels, the faster you can complete the design, saving time and money.
Low-bleed white. When printing on color fabrics prone to bleed onto white (a problem known as dye migration), use a low-bleed white. These formulas have dye blockers that attack the garment dyes as they migrate through printed white ink deposits.
Dye blockers in the ink bleach the garment’s dyes, a process that remains active for a short period of time after the garments come out of the dryer. Do not stack garments printed with low-bleed whites immediately after they exit the dryer. If you do, it will cause “ghosting” on the backs of other garments stacked on top of these hot prints. Ghosting is a pale, dupe image transferred onto one shirt from the uncured print it was stacked on.
Avoid ghosting by laying out several printed garments and allowing them to cool completely before putting one on top of another. The extra step is worth the trouble because the result is a bright white print.
Low-cure white. This type of ink was designed for printing on heat-sensitive materials and fabrics prone to dye migration problems. The PVC resin in low-cure inks was developed to cure at a lower temperature than the approximately 320°F required to cure standard plastisols. With low-cure inks, printers can lower dryer temperature to reduce dye migration and problems with fabric scorching. Low-cure whites aren’t a standard product for most ink suppliers; they’re usually available only as a custom formula for buying in large volumes.
Finally, some ink manufacturers offer white inks designed specifically for the performancewear market. These inks are specially formulated for printing on performance fabrics, poly-blends, moisture management and stretch fabrics. Most of these inks cure at the low temperature of 285°F, slightly lower than conventional plastisol ink.
Remember, two wrongs don’t make a white right. In fact, the more wrongs, or printing mistakes, you’re getting, the more likely it is that you’re not using the correct white ink. Take the time to learn about the variety of white inks available from your ink supplier.
James Ortolani has more than 30 years experience in the decorated apparel industry, specializing in hands-on direct screen printing and heat transfer production. He has worked for main industry suppliers, and currently serves as R&D project manager for Stahls’ DFC. For more information or to comment on this article, email James at email@example.com.
More Production News
T-shirt screen-printing veterans Danny Gruninger, of Denver, Colorado, based DayBirds Printing, and Rick Roth, founder of New England’s Mirror Image Screenprinting & Embroidery and Ink Kitchen, talk fast, efficient setups as part of the Shop Talk education series at the 2022 Impressions Expo in Fort Worth, TexasFULL STORY
Garment decorators always are looking for ways to create special effects (SFX) with their screen-printed designs by offering specialty inks — puff, glitter, suede, shimmer, high-density and more — to keep their artwork on the cutting edge.FULL STORY