Garment screen printers seem to be fixated on white plastisol inks. Find out why.
By Mike Ukena
I categorize white plastisol inks into six basic types. You may argue the validity of having more or less, but by my count, the categories are cotton opaque, low-bleed opaque, poly opaque, mixing, athletic opaque, and process highlight. Each has its own properties and cost (Table 1). Even though five of the six ink types I’ve listed are classified as opaque, that does not mean they necessarily cover properly in one pass. Rather, they are as opaque as they can be while still retaining their printability. I’ve left out specialty whites, such as high density or suede, as they really are different in application. The white inks that I’m talking about are the ones used for underbasing and highlighting.
Cotton whites These should be the most common whites used by most printers. They are designed to be used on cotton, nylon, and any other non-dye-sublimating fabrics (i.e., polyester or polyester/cotton blends). They have an excellent after-print finish, they take overprinting well, and they do not have any tendency to ghost (Figure 1).
Few printers actually use a cotton white. Instead, most use a low-bleed white for all fabrics. Their reasoning is usually that it’s easier to use one white for everything. While I understand the logic, the downside is that they are using a more expensive ink—and one that also gives a rougher finish and may result in fabric ghosting (more on ghosting later).
Low-bleed whites These inks are designed for use on polyester/cotton blends. They contain chemicals that are designed to block the dye that may be released from polyester fabrics and prevent the color from tinting the image. Most of these inks do very well in accomplishing this mission. Some do it better than others, either because of the amount of blocking agents in the ink or the ability to flash extremely fast, which minimizes the amount of flash necessary and thereby reduces the amount of dye that may be released.
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