Garment screen printers seem to be fixated on white plastisol inks. Find out why.
By Mike Ukena
Unfortunately, these inks have become the standard in our industry. Low-bleed inks, in addition to the attributes mentioned above, contain chemicals that cause an expansion of the ink film, which results in more texture than in cotton whites. This rougher finish can also lead to craters, where the white underlay may show through the finished print after the finished print is cured in a hot dryer (Figure 2).
The other negative—one that does not happen often, but will always happen when you least want it to—is ghosting. Ghosting is a phenomenon in which low-bleed chemicals out-gas from the print and attack the dyes in the fabric in contact with the print. This usually occurs when the fabric is stacked hot and allowed to sit for an extended period, like overnight, and the out-gassing chemicals bleach the dye right out of the cotton fabric above.
You will never see ghosting on standard colors such as black and red. You will never see it on poly-blend fabrics. Where it will occur is on fashion-color fabrics and pastels, where the dyes are not as stable. I’ve most recently seen the effect on pink, sage, pale yellow, and very light tan fabrics.
Polyester whites Polyester low-bleed whites are basically your regular, low-bleed white inks on steroids. The chemicals that help to block the polyester dyes are maximized and are limited only by the need to keep the ink printable. Most printers are a little shocked by the ink’s consistency and viscosity when using it for the first time. Poly whites are the most expensive white inks because of all the added ingredients. They are only needed on 100%-polyester fabrics and are really too strong and too expensive to use as a regular, low-bleed white ink on blended fabrics.
These inks have excellent opacity, but they still require a print-flash-print technique for proper white-only coverage. Also, please note that the manufacturers call them low-bleed, not no-bleed. Improper technique or bad fabric can still defeat these inks.
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