How to Improve UV Ink Adhesion

Are you looking for ways to improve your UV printing ink adhesion?

Well, we've got great news! Whether you're trying to get better print results on metal, glass, or wood, or you're just troubleshooting ways to fix prints that won't stick to your substrates, this post has your solution.

Today, we're diving deep into some of the best tips around to keep your UV prints sticking like they're supposed to.

Why Ink Adhesion Matters in UV Printing

The importance of UV ink adhesion can't be understated. When a print fails due to poor adhesion, it's not only frustrating, it also forces you to reprint or abandon the design altogether.

But prints that won't stay put aren't just annoying. They actually cost you ink, time, and money.

Print quality is also important, especially if you own a business. In that instance, UV prints that flake or peel can force you to lose sales and/or affect your reputation.

Don't worry, though; the secret to getting durable UV prints can be distilled down to just a few simple strategies.

Top Strategies for Improving UV Ink Adhesion

Select the Right Substrate

All substrates are not created equal. Some simply hold ink better due to their surface energy. This energy is referred to as "wetting" and can be checked by sprinkling a few drops of water onto the substrate. If these drops bead, then the surface is potentially problematic.

If not, then your surface will likely hold ink well. To eliminate any confusion, you can also purchase Dyne test pens to evaluate a surface's wetting properties.

Discussing the science behind wetting is a bit out of the scope of this post; however, you should be aware that the better the wetting, the better ink will adhere.

Proper Surface Preparation and Cleaning

Cleaning and prep are important parts of any additive manufacturing process. When it comes to UV printing specifically, dirt, dust, and oils can act as a barrier between ink and object.

So, to get the best results with your UV printer, you'll need to understand how to clean and prep your substrate's surface. In some cases, this prep can be as simple as wiping away dust with a lint-free cloth.

In other cases, you'll want to incorporate a little isopropyl alcohol to remove any embedded grime.

Isopropyl concentrations of 70% or greater are perfect for this task, as they will also remove moisture from the substrate surface. Just make sure you test the surface beforehand because alcohol can damage certain substrates.

For porous materials, you'll want to make sure they're entirely dry before printing onto them.

Additionally, some materials-3D-printed filament, for example-may even benefit from a little light sanding.

Using Adhesion Promoters and Primers

Adhesion promoters and UV ink primers add another layer to your print that can help keep UV ink from flaking or peeling prematurely.

If you see constant flaking or peeling, many industry professionals recommend an adhesion promoter. You'll often spray or roll these promoters onto an object before starting the printing process, and they'll cure when the UV lamp of your printer turns on.

Select the Right UV Ink: Flexible vs. Hard

Like adhesion promoters, there is no single best ink for glass, metal, or plastic that will ensure 100% adhesion with every print. You should, however, consider your application. Rigid inks, for example, the standard white ink that ships with our own eufyMake E1 UV printer, are meant for rigid surfaces. Trying to use rigid ink in a flexible application could create issues.

Even if you choose the proper ink for your project, there is also the potential for under- or over-curing. Under-curing can occur if ink is not exposed to UV light for a long enough amount of time. This practice causes the ink to remain softer than it should. Because UV inks rely on proper curing to stick well, leaving them under-cured is a recipe for disaster.

Over-curing, on the other hand, happens when a print is exposed to UV light for a significantly longer time than required. This creates brittle prints that can chip or crack. However, there is great debate within the UV printing community surrounding over-curing. Some makers will try to convince you that over-curing isn't an issue. Others disagree.

Troubleshooting and Testing UV Ink Adhesion

One way to test your substrate's ink adhesion is by performing a cross-hatch and tape adhesion test. This consists of printing on your substrate, placing a small piece of tape over the ink, and then using a specialized tool to scrape the surface of the print beneath the tape. The tape is then removed and assessed.

However, instead of purchasing expensive tools or learning a new testing procedure, you can perform a small test print on a substrate scrap to see if the ink adheres properly. It's a quick and dirty way of evaluating adhesion that will only cost you a tiny bit of time and ink.

Fine Tune Your Print Settings

Many UV printers will allow you to fine-tune your print settings for optimal adhesion via their onboard software. The eufyMake Studio software, for example, lets you choose from several substrate and quality options so that you can dial in your projects easily.

You can adjust ink thickness, add texture, and even preview your print before it's sent to the printer. We recommend you experiment with these settings in eufyMake Studio until you find the ones that fit your project the best.

The Fix for Common UV Printing Adhesion Issues

Solving UV ink adhesion issues is not always a walk in the park. We hope the tips here can help you fix those kinds of issues a bit more easily. Likewise, with proper preparation, tuning, testing, and troubleshooting, you can be confident your UV prints will come out great every time.

FAQs

How Long Does UV Printing Take?

Though most prints can be completed in a few hours or less, UV printing times will ultimately be dictated by the printer, the project, and the desired quality of the print. Higher-quality prints usually need more time than experimental drafts, as do larger, more textured prints. UV printing requires patience, so it's best to start a print and go do something else while it's being completed.

Why Does UV Ink Not Stick?

Several factors influence UV ink's ability to stick. Surface cleanliness and surface prep are the two most prominent, however. Others include using the wrong type of ink (flexible vs. rigid), under-curing, and an improperly tuned printer. With the guide above, troubleshooting UV ink adhesion issues doesn't have to be difficult or frustrating.