Water Based Screen Printing Inks the ultimate guide
As the demand for non-PVC printing and more environmentally friendly inks grows and increases, screen printers using traditional plastisols are at a crossing point.
For them and every screen printer, who have or will have to deal with water based printing inks. Here are the Water Based Screen Printing Inks the ultimate guide!
Myself looking always for Environment-Friendly screen printing solutions. We need to talk about water based screen printing inks. We had before the 90s with water based inks, then we got the new innovation at this time, plastisol inks and now, we go back to water based screen printing inks.
Why this changes?
In the 80s we did not have really other option than water based inks. The screen printing evaluated with automated screen printing machines at that time. We faced difficulties printing water based inks on automatic screen printing machines. The industries came up, with plasisol inks, what have a much faster flash point. The ink NEVER dried in the screen, it did not have an expiring date and it been perfect for our automatic printing machines.PVC Plastisol inks easily gel at (ca. 80 °C) (176 degrees Fahrenheit ) and fully cured in seconds by around 165 °C (320 degrees Fahrenheit).
As the name already tells us, traditional plastisol ink is based on liquid plasticizer, a type of PVC. The slow exudation of the plasticiser and its release into the environment can be problematic. And nowadays, we realize, that environment is very important to us, incl. the softeners in the plastisol ink for humans.
As the world is turning fast, they created, Phthalate Free Plastisol ink and plastisol alike inks what are PVC & Phthalate Free.
This could lead, and I have seen this many times, that people talking about water based inks. That in general they would be environmental friendly. This is not the case, even in water based inks you can have polymers and other stuff.
So, what is the right ink to use?
“Green” screen printing inks, must comply to one or the other oeko lable like:
- STANDARD 100 by OEKO-TEX® conform
- Cradle to Cradle Certified™
- Global Organic Textile Standard (GOTS)
This is, what you should check out, this is a good starting point, to be sure you have used proper ink, with standards. In another article, I will cover this deeper.
But now, you learned, that plastisol ink is easier to print on automatic machines. And now the trend is back to water based screen printing inks.
How to overcome the printing problems, what we had before with the water based inks on the automatic printing machine.
- The water based ink of today is much easier to handle than before. They do not dry out that fast, but for sure they still do.
- we have additives for water based inks, which keep them running on an automatic machine easier.
- And this is the point, where I really wanted to come to. we have more knowledge on how to print water based inks. And here I like to show you this quite old video from 2013.
My word, if you really want to learn EVERYTHING about on How to screen print water based inks. It’s a must-watch these 6 Videos as the ultimate guide for screen printing water based inks! It explains really everything you should know. It starts from color separation and it goes to every department in your screen printing shop. My hat goes to Mark Gervais, who really explains well, what you need to do, to print water based inks.
I agree the sound, could be better, but hey, these videos are from 2013 and it’s for free! But if you really follow his advice. You will master in no time, water based screen printing and you save a lot of time and errors.
Thanks again to Mark Gervais who really went out of his way here to explain to us screen printers what is so important and what is so often overlooked. And I’m still astonished by how few views these videos got.
These water based ink videos talk about:
- Separations / Film Output
- Screen Making
- Inks / Ink Prep
- Screenprinting – Press Set-up
How to do Color Separation for Water Based Inks
How to do Color Separations and Film Output for water based inks. As you would for Plastisols but what you need to be aware of is:
The importand factors for seperation and film output
- Dot gain/curves
- Superior edge quality/resolution of the film
- Linearized output -d-max 3.0 or higher…
- 50-60 dpi
- Elliptical Dot
- 22.5 or 67.5 angle
Screen Making for Water Based Inks
Is there a difference between Plastisol ink to Water-base Inks, on how we do our printing frames? Yes, there is, this video will cover the topic of how to make the screen printing frames and talks about Emulsions.
What to consider for screen making
- Mesh Selection …
- Thin thread mesh = percentage of open area
- Tension levels – 25 n/cm
- 50 dpi /135-160, 60 dpi /160-225
- Selection = “waterbased” dual cures
- Coating = EOM is “required”
- Correct drying methods, moisture removal
- Storage & storage conditions
- Calibrated & consistent
- VERY IMPORTANT!!!
- Emulsion Hardening
- A&B, apply with a paint roller
- Must be “cooked”… or else!
- Again, correct drying methods
- Post Exposure
- x2 the “exposure time”
Screen Printing Water Based Inks and Ink Preperation
A very important chapter, ok all are important, this is why he focused more on the inks, but well, if you are serious about water-based printing, you need to follow all.
What ink types we have in water based screen printing
- Ink Types
- Conventional low solids type
- Newer “high solid acrylic” (HSA’s)
- Specialty inks – yes, MANY!!!!
- Ink Systems
- RFU’s (ready for use)
- As is, just add ink and print…
- Base & Pigment
- Clear base & white = build opacity
- Add pigments, understand limits
Water Based Inks and Additives
We have quite a lot of additives for screen printing. But please check out here, if these are in compliance with OEKO-TEX or other green labels.
Everything you add to your screen printing ink should conform! incl. the pigments.
Additives are very helpfull in screen printing water based inks
- Science & Chemistry
- Ph plays a very important role
- Impacts viscosity & performance
- Fixers / Cross-linkers
- Fixers = help to “fix” pigment to resin
- Useful in marginal cure situations
- Effective in lowering time and temperature requirements
- Traditional = glycerin & urea
- Advanced technologies …
- Activated trigger points about 170°F (77 degrees Celsius)
- This is what makes printing these new waterbased inks easier than before!!
Screen Printing Press Set-Up for Water Based Inks
Press setup, squeegees, and platten temperature, is a big factore in Screen Printing waterbased inks.
- Just as you would plastisol
- Consistent pallet levels / off contacts
- Same angle, flood and squeegee pressures
- The same rules apply here – sharp and right
- Edge condition is critical !!!
Getting the Press “Ready to Run”
Set up and “dial in” each printhead & screen in terms of:
- Off contact
- Squeegee = pressure, speed, angle
- Print Each Screen
- Individually to ensure each screen & printhead are “dialed in and ready to go”
Almost “Ready to Run”
- Warm the pallets = VERY CRITICAL!!!
- Set a dummy head for “timing & sync”
- Cycle the machine with a dummy head & “flashing” until the pallets reach 140°F-150°F (60-65 degrees Celsius) (measure using a “ray-gun”)
- Print Each Screen
Flash Cures & Pallet Temp Control
- Waterbase Inks flash “differently”
- They require HOT AIR not straight HEAT
- “Hair Dryers” work better than IR …
- Monitor the “pallet temps” – CRITICAL!!!
- Maintain even/level pallet temps between 140°F-150°F otherwise, problems WILL occur such as ink drying “ON and IN” the mesh
Water Based Inks and Curing how to do
Curing Screen Printing Water Based ink is totally different than Plastisol inks. You will understand why, by watching this session. If the PH still plays a role in our new printing inks today on the market, I’m not too sure.
Why is water based ink so different than plastisol ink for curing
- Require exact time and temperature
- Generally between 2.5 and 3.0 minutes
- 310°F-330°F (155 -166 degrees Celsius) (depending on ink-additives)
- High airflow/circulation with moisture evacuation – “do not push ‘hot ‘n’ wet’ air around the dryer” – won’t work!!!
- How do waterbase inks cure … ?
- Very differently than plastisol!!
- Since inks are built on the alkaline side, inks need to change the pH from “alkaline” to “acidic” as quickly as possible …
- Why? Lowering the pH causes thickeners to be ineffective which lowers viscosity
- What happens then? When the viscosity is lowered, the ink will “settle” into and penetrate the yarns of the fabric
- What happens next? From there, water needs to be completely removed
- Once that happens, then and only then, can the “ink temperature” rise to the correct and specified temperature
- When that happens, the remainder of the components in the ink (resin, pigment, etc.) can BIND together for a secure ink film
Who said that screen printing is easy? Yes, it is, but if you go deep into the professional side of screen printing, you start realizing, that there are so many factors. But this Water Based Screen Printing Inks the ultimate guide, should guide you well, for your future. How to Screen Print like a Professional he controls your variables. It is so important that I can never mention it often enough.