How to Troubleshoot Screen Printing with Waterbased Ink
The Halo Effect
Are you noticing that sharp edges and details of your artwork aren’t printing properly? Are square corners appearing more round? Or perhaps the print is lighter in some areas. We like to describe this common issue as the halo effect. This is caused by the the ink drying up in your screen, when printing with waterbased inks.
Tip 1: Clean your screen. You have to get those sharp edges back! The challenge of printing with waterbased ink is that you have to move quickly. As the water in the ink dries, the ink gets thicker and clogs up the tiny holes in the screen. To avoid this, not only must you work fast enough to prevent the ink from drying in the screen, but you have to maintain the proper liquidity by adding water. A safe way to add water to your ink is by using a spray bottle to mist your ink after you’ve flooded your screen.
Tip 2: Proper flooding. The most common reason this occurs is because the layer of ink is too thin on your screen and it can’t cover the mesh well enough to prevent the open areas from drying up. Be sure to have enough ink on your screen to get a proper flood and cover the art completely.
Tip 3: Always have a spray bottle handy. As mentioned above, when your ink is flooded, shoot the mist into the air 2 – 3 times and let it fall gently onto your flooded screen.
Splooging? You’re probably wondering what that term refers to. Have you ever printed and noticed the ink bleeds excessively from the outer edges? Splooging is when the ink has too much water in it, which causes it to bleed beyond the edges of your artwork. Although it is necessary to add water throughout your print job, be careful not to add too much. The goal is to maintain the same consistency throughout the job, so all your prints come out nice and clean.
Tip 1: If you have too much water ink your ink, you have to let it dry out a little until it gets back to the optimal consistency. Depending on how wet your ink is, you might be able to get away with doing several test prints on newsprint to let it dry naturally. Do this until you achieve a clean print.
Tip 2: If you accidentally added way too much water, you should scoop it all up from the screen, put it back in the can, and mix it back in. Then let it sit out for a little to air dry. If you are in a crunch for time, a technique that has worked for us is drying the ink using a heat gun from a safe distance while stirring the ink and monitor the thickness.
Have you noticed on some of your pulls/pushes that your image comes out thicker in some areas? When there isn’t enough off contact, your screen is unable to spring back up high enough, and the ink on the screen sticks to the ink that was laid down on your print. We call this drizzle. Drizzle can also occur when you’ve left a trail of ink on the screen. Because you didn’t have enough off contact, the trail you left once again, sticks to the ink you just laid down, causing an inconsistent print.
Raise the off contact. Depending on the type of material you are working with, your off contact will vary (e.g. more off contact for thicker materials). There should be enough off contact so that after you push/push, there is at least ¼” space between the screen and your printing surface.
Clean your screen and test the off contact. Push/pull the ink to one side. Then clean both sides of the screen. Afterwards, run a test print to see if the problem is resolved.
If the problem is still occurring, consider pushing/pulling your ink faster, or not as hard. Drizzle can also occur if you are pushing the squeegee too slow and not allowing the screen to bounce up, or if you are smushing your ink by pushing to hard.
Ever notice your squeegee moving by itself or your screens lifting by themselves? This is called a Poltergeist. Ghosting, on the other hand, is when there is a faint print next to your image causing a “ghosted” version of your print. This usually occurs on prints that require multiple passes and there is an inconsistency in the way you push/pull, or when your substrate or screen isn’t secured properly causing the print to shift.
Wipe the underside of the screen and run a few test prints. Make sure the screen is secured on your press and the substrate is secured on the palate. This might mean adding more adhesive on the pallet, or firmly pressing out the slack on a sweatshirt so there is no movement when you push your squeegee.
Once you achieve a clean print on newsprint, make sure to maintain a steady push/pull and a stable squeegee angle.
Conclusion: If you’re thinking we made these terms up, you’re right! We learned from trial and error over decades of printing on various substrates. Naming these issues makes them easier to identify and troubleshoot. The key to any screen printing job is patience, cleanliness, and control. All of the problems described above occur when we don’t take the necessary time to set up properly and get lazy during printing. If you maintain a methodical, structured approach to every job and do your best to be organized, and reduce the number of variables your projects will have less errors and look amazing.