Screen Printing With Water Based Inks: 5 Solutions

Business Lessons

So many screen printing shops have a hard time working with water based inks.

It's not that water based inks are difficult. It's that most shops don't know where to start. They don't know they might want to get a reptile fogger (but I promise more on that later).

This article will answer 5 common questions about water based inks and give you tips you can use in your shop to get the most out of this exciting medium. There's some basic concepts to understand about working with water based inks before we dive in:

  1. The less water you have in your ink, the harder it is to work with. Water based ink has lots of water in it (seems obvious, right?). But as the ink loses water, it becomes stubborn and hard to work with.
  2. Think about water based ink like it's blood. If you get a small cut, it scabs up quickly. But a larger wound has flowing blood and won't immediately scab up or dry out.
  3. Keep it moist, keep it moving. You've got to manage water based inks so they don't dry out and give you issues.

Let's go further into these eco-friendly, super-soft, ultra-durable, 100% breathable inks!

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1. Which water based inks are best?

Everyone in the industry likes to fight over which ink is best.

It's really like asking which pizza is best. (It's Pequod's, though. I may have to watch my back for a while.)

The truth is very simple.

The best water based ink fulfills two criteria:

  1. It works on your shop's press.
  2. You have a helpful supplier for it.

If the ink comes from a supplier you trust and it works for you, then it's good ink. Don't worry about the other noise.

To find the inks you like, prioritize testing different inks. You can probably get samples from sales reps. Learn from the process and experiment with your techniques. Remain open to surprises and changes in your process – it's worth the investment in time and energy.

2. What types of water based inks are there?

Water based inks are literally any ink that has water as its key component.

That tends to throw people off.

Traditional water based and discharge inks don't sit on top of the shirt like Plastisol does. Instead, the actual fibers of the shirt are altered. This makes for a long-lasting print that's as soft as the shirt is. Not all water based inks work this way, though!

So here's a breakdown of the different water based inks:

Ink Type Ink Consistency Ink Details
Traditional water based ink Very runny, almost liquid Alters garment's fibers, soft hand feel, must stay wet
Discharge ink Fluid, but has more viscosity for whites and bright colors. Utilizes an activator to "bleach out" the existing colors on the shirt
Acrylic ink Thicker, like Plastisol ink Does not alter garment, sits on top of fibers

Acrylic inks are becoming more popular thanks to the growth of digital hybrid printing (also known as "the giant new machines that cost as much as a small house"). Lots of digital printing machines print on top of a tradition screen printed underbase – and most require some type of acrylic ink.

3. Why do you want to screen print with water based inks?

Plastisol is incredibly easy to use. It won't dry up sitting on a screen and will never puddle. So why should you switch to water based ink?

  1. It's a cleaner and more environmentally friendly product. Water based inks are not based on petroleum, nor do they contain toxic unpolymerized polyvinyl chloride.
  2. They're becoming popular in Asia, Europe, and South America. Water based inks are huge internationally.
  3. Water based inks feel amazing – they have "superior hand". In most instances, water based inks simply feel much softer.
  4. Water based inks are breathable. Since it's likely you're going to print on some kind of athletic wear, it's nice to know that water based inks typically allow the garment to remain breathable even if you're doing a fairly large print.
  5. Water based ink prints are extremely long-lasting. The print will typically last as long as the garment!
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4. What should you do when water based inks are drying in the screen?

This is simply the most common issue with water based inks, particularly with top-coat water based inks like acrylic ink.

In the fine art world, the simplest solution is to add a retarder: glycerine would be added to ink to keep it from drying.

There are three solutions for slowing down the drying process with your water based inks:

Use helpful chemicals to slow down drying.

Check with your ink manufacturer to see what kind of retarder they suggest.

A water based ink retarder slows the drying time and increases the "open time". Some manufacturers offer multiple additives that alter how the ink behaves. In my experience, using the recommended retarder combined with a lubricant is the best way to keep ink flowing and slow the drying process in the screen.

Get a reptile fogger.

I promised you that I'd say more about the reptile fogger.

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Here's a brilliant hack to keep your water based inks from drying up in the screen:

Use a reptile fogger to keep your ink wet!

These cost about $50 when they're new, and you get a 1 liter system that sprays a cool mist. It's attached to a hose, so you can move the hose and clip it wherever you'd like to keep the fog directed at your screen.

Here's an example:

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Be sure to use distilled water in your fogger to keep contaminants out!

Use lube.

All jokes aside, throughout the years I've learned that coating your screens with the ink manufacturer's recommended lubricant is critical.

Before any water based ink goes on your screen, apply lubricant with a clean cloth and rub it liberally into the open areas of your image. Use a little water to help spread the lubricant completely through the mesh, then wipe it clean. 

By penetrating the entire mesh with lubricant, you slow down drying and make printing much smoother.

5. What should you do when water based inks break down your screens?

This is the other big problem shops run into when they start printing with water based ink: their screens start breaking down. Water is the universal solvent, after all.

Emulsion formulation is key to keeping your screens from breaking down. Emulsions have different solid content levels, different levels of durability when exposed to different inks, different exposure properties and so on. So how do you choose?

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Virtually every supplier for garment decorators has a good emulsion that you can use. You may have to alter your emulsions to get the toughness you'll need.

When in doubt, go with Diazo for the best durability when screen printing with water based ink. Ideally, you mix powder Diazo blended with water into the emulsion. This can create a powerful emulsion that is more durable than standard photopolymer emulsions that are ready for use out of the bucket.

Proper exposure leads to optimum cross-linking. Cross-linking is when the semi-solids in your emulsion become a solid through reaction with UV light. Take the time and invest in getting exposure 100% right.

  • Get an exposure calculator. The Kiwo-Ulano ExpoCheck is a low-cost investment and will pay for itself many times over.
  • Consider the exposure unit. There's some debate about whether LED exposure units will create proper cross-linking like mercury vapor bulbs do. I'll leave that to the real scientists. But you may need to experiment with different emulsions to get durable results when you switch light sources.

Always post expose.

Here, I'm going to say it louder: ALWAYS POST EXPOSE!

This is a super simple step that so many shops overlook or think isn't necessary.

After you've exposed your screen and it's dried off, take your screen and expose it to more light. Turn off your exposure unit's vacuum function and expose the screen ink-side down (opposite of how you normally expose screens). You can even just expose it to sunlight for a minute or so.

The point is to further harden the ink-side of the screen. This is a very easy way to improve the durability of your screens.

Conclusion

Water based inks are an opportunity to offer your customers the longest-lasting and softest custom shirt possible. It's a screen printing technique that adds value and impresses clients. Too many screen printing businesses are afraid to experiment with new techniques – but water based inks are a fantastic opportunity to do something new.

Now that you know where to start, and are armed with some practical tips, go find out how you can utilize water based inks in your shop.

Photo courtesy @rizallabrie


Matt Marcotte has over a decade of experience in the screen printed apparel industry. He works with shops to improve their sales and production through thoughtful consulting. Visit his website for more insights.


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