The Evolution of High Solids Acrylic Ink
With consumers demanding the softer feel of water base prints, the time is now to take the leap.
Two apparel trends, which have been evolving over the past decade, have been changing screen printer’s choice of ink.
Performancewear has increased in popularity because it’s comfortable to wear; wicks moisture away from the body; and, in many cases, its lightweight breathability feels cooler than 100% cotton. While performancewear started out as an athletic and activewear garment, it now has evolved into everyday streetwear as well.
The basic T-shirt also has evolved to meet consumers’ preference for a soft feel and natural drape. To make shirts softer, yarns are ring spun, treated with enzymes and finishes, and are knit from finer gauge yarns. The result is fabric with a butter soft feel against the skin.
With the greater demand for these two types of apparel, screen printers have had to change their inks and printing techniques so that the softness of the garment is not negated by a thick, heavy bulletproof print on the front. While techniques have emerged to print a softer hand using plastisol ink, many printers are opting to switch to water base.
The transition from plastisol to water base for some is not an easy one. These two inks behave and perform differently and require changes in procedures and practices to be successful. Probably one of the biggest challenges with water base ink is how quickly it dries. While you can leave plastisol ink in a screen overnight and simply resume printing in the morning, with water base, you may not even have to time to use the bathroom before it begins drying in the screen.
The drier the climate your shop is in, the more challenging water base printing can be requiring screens be misted with water to keep the ink open and flowing during a job. They have to be cleaned up immediately after use, and their fast-drying properties can result in more waste than is typical with plastisol.
Water base inks require a different type of stencil, one which is water resistant, and will require post exposing. It also is ideal to use a coarser mesh. It is easier to keep a coarse mesh open than a finer one. So if you need to print fine lines, this will be more challenging with a water base ink than plastisol.
Discharge inks, which are water base, are popular for dark shirts, because they bleach out the shirt dye, eliminating the need to print a white underbase. This allows for a softer hand on darks. But these inks contain zinc formaldehyde, an unfriendly chemical that not only smells bad, but if a splotch accidentally gets on an unintended part of the shirt, it bleaches that spot, making that garment a reject.
It prints transparent, which makes it very difficult and sometimes impossible to see the print until it’s gone through the dryer. This increases the chances for error, and discharge works only on 100% cotton shirts colored with reactive dyes.
The Next Generation of Water Base
With apparel trends driving printers to water base ink and more printers wanting to use them, this set the stage for ink makers to come up with a water base product that provides a soft hand with fewer hassles. And that product is a high solids acrylic water base, also known as HSA.
HSA inks address the biggest challenge of traditional water base inks; they dry slower, keeping screens open. You can go away for half an hour and after a couple strokes, you can reopen it. We’ve run it at several trade shows where there’s sometimes 20-30 minutes between prints and with a couple strokes, it’s good to go.
They also provide a solution for dark shirts that are not reactive-dyed 100% cotton and cannot be used with discharge ink. And you can see the print before it goes through the dryer.
HSA inks are more opaque than water base inks. HSA White bases often require a second stroke to achieve the desired degree of opacity. In most cases, its opacity is similar to plastisol.
They also are more elastic than traditional water base, more closely resembling plastisol’s stretchiness and ability to bond to itself. Traditional water base can be brittle and crack. While a single layer of traditional water base is fine, multiple layers can create a harsher hand.
Depending on the brand, the cost of an HSA ink may be slightly more or the same as plastisol. There are inexpensive plastisols on the market, which are lower quality, but they are not comparable.
Who is switching to HSA?
Although HSA inks are easier to use than traditional water base inks, they still are not as easy as plastisol. For someone switching from plastisol to an HSA, they will need to learn how to work with it. But as regulations continue to tighten on plastisol inks with PVC, more people will be willing to make the switch.
In their favor, HSA inks have a softer hand than plastisol, and the appearance and aesthetic, which is smoother and flatter, is different. For a printer with a mindset of “I’ve got 20 orders to do today, and the customer is fine with this, and I just want whatever is faster,” that person is going to stay with plastisol. But for printers who want to produce a better product, they are converting easily. Eventually it’s going to come down to owners who want high quality, and those whose customers are going to force them into it.
For faster curing at lower temperatures, it’s recommended to add a low-cure catalyst to HSA ink, especially if the dryer does not have forced air. A lower curing temperature also saves energy as the dryer can be turned down. Note that any inks that have a catalyst added need to be used within eight hours.
When printing polyester with HSA inks, a dye blocker is advised. A black blocker is used as an underbase and stops dyes from migrating through the inks, changing the desired color. It will create a heavier hand than without the blocker, but still softer than a traditional plastisol print with an underbase.
For dark shirts, you’ll want to do the usual white underbase, flash, white base and then print your colors on top. This creates a surface like white paper and helps colors to pop.
When printing spot colors, especially if they are big areas, it’s best to flash between colors. This helps avoid pickups. Simulated color can usually be printed wet on wet.
HSA inks are making it easier than ever before to get into water base printing. If you have been thinking about it, now may be the time to get a quart of ink and try experimenting to see how it works for you.