There are a variety of benefits to using water-based ink in your screen printing shop. You don't have to use harsh chemicals to clean up after using them, they're better for the environment, and it's easier to do soft color printing with them. However, there's no denying there are also some challenges to using this type of ink that could lead to costly mistakes if you don't know how to deal with them. Here are three common issues with water-based inks and what you can do to solve them.
Drying on the Screen
Possibly one of the most frustrating problems with using water-based ink is they tend to dry faster on the screen during long print runs. This can make it difficult to take on big jobs or at least complete them in a reasonable and profitable amount of time. However, there are a couple of things you can do to address this issue.
If your shop is located in a dry area or the humidity is low in your facility for some reason, the first thing you should do is install a humidifier. Water-based inks dry quicker due to evaporation, and the problem is exacerbated by dry environments that essentially suck the moisture out of the ink. Increasing the humidity in the printing room will help alleviate this issue. Additionally, keep a spray bottle nearby and mist the screens when it appears the ink is beginning to dry.
Back flooding after printing the image is another thing that can prevent the ink from drying. Just be sure you're using the right flood strokes to prevent the image from bleeding. Alternatively, you can use a special additive designed specifically for water-based inks that slows down the drying process, though you may need to adjust your curing times to compensate.
Lastly, it's critical you take good care of the inks when they're not in use. Always close the containers between applications. Not only will the inks dry out if left uncovered, but they may attract bugs or grow mold because of the water they contain, rendering them unusable.
Longer Cure Times
A second issue associated with water-based inks is they require longer curing times than plastisol-based inks. With plastisol, the ink only needs to be under the heat for a few seconds to get it to bond to the fabric. With water-based inks you must cure it for two to three minutes at 300 to 320 degrees Fahrenheit to remove the excess water so the pigment can attach to the fibers.
One option is to use a conveyer dryer on low speed. Be sure to set the temperature so that it gets to the required level and that there's adequate air circulation so the steam can escape. Another option is to additives. A low-cure additive reduces the temperature needed to cure the ink, while a crosslinker reduces the amount of time needed to normal production speeds. Both will let you use your current equipment, so you don't have to buy a specialty dryer just to accommodate water-based inks.
A third problem with water-based inks is sometimes they can separate over time, especially bright or fluorescent colors. As mentioned previously, it's important to keep the inks covered when they're not in use. However, it's also important to stir them up every once in awhile, especially inks you don't use often. This will minimize separating, ensure the ink remains usable, and minimize waste.
For more tips on dealing with the challenges of using water-based screen printing inks or to purchase screen printing supplies for your shop, contact a screen printing supply company.