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by Brett | Jul 7, 2026
Hi everyone! I'm Mingyu Wang, CEO of Morpho, but you can just call me Brett.
For many makers, crafters, designers, and artists, UV printing may still feel unfamiliar. Through these short, topic-based posts, I want to share practical explanations that make UV printers easier to understand and easier to use. If more people in the community can quickly grasp the principles and best practices behind UV printing, it will help everyone create with more confidence.
For people who already know UV printing, just hearing the phrase "white ink clogging" is probably enough to cause a headache.
So let's start with the root question: why is white ink so special, and why does it clog more easily than other colors?
White ink is arguably the most important special ing
With a home printer, we usually print on white paper. That is like drawing on white paper as kids: whatever color your pen is, that is more or less the color you see.
UV printing is different. We are printing on real objects, and real objects come in all kinds of colors. Your mug might be pink. Your cardstock might be green. Your acrylic sheet might be black.
Imagine trying to print a bright cartoon character on black acrylic. Without white ink, it is almost like painting watercolor on black paper. The colors cannot truly shine.
The magic of UV printing is that you can first lay down a white base on the object. No matter what color the object originally is, this white layer works like carrying an invisible piece of white paper with you. Once that base is there, vivid colors can sit on top of it.
In that sense, white ink is the soul of UV printing.
Like other UV inks, white UV ink contains several key components:
- Oligomers, which form the skeleton of the ink and influence hardness, adhesion, scratch resistance, and other properties.
- Monomers, which help adjust viscosity.
- Photoinitiators, which trigger UV curing when exposed to specific wavelengths of UV light.
- Pigments, which provide color.
- Additives, which help control stability, flow, dispersion, and other behaviors.
What makes white ink uniquely useful, and uniquely difficult, is its pigment: titanium dioxide, or TiO2.
There is a funny connection here. Titanium dioxide is also a common active ingredient in sunscreen. The sunscreen you put on your face and the white ink inside a UV printer can share the same basic chemical substance.
To create strong whiteness and opacity, the titanium dioxide particles in white ink are usually milled and controlled to around 200 to 400 nanometers in size.
That tiny particle size is useful for printing, but it also creates problems.
When people say the white ink channel in a printhead is clogged, it is usually related to one or more of these issues.
1. Aggregation
Titanium dioxide particles naturally tend to gather together.
This is not because the ink is badly designed. It is related to thermodynamics and molecular forces. Particles try to reduce their exposed surface area and lower their energy. Van der Waals forces also encourage them to attract one another.
Think of a cocktail party. At first, everyone enters the room individually. But after a while, people naturally form little groups of three or five to chat. Titanium dioxide particles behave in a similar way.
Small clusters are not immediately scary. But when these clusters become large enough, they can cause deflected jets or even block the printhead completely.
It is like those people at the party suddenly locking arms. Once they do that, they can no longer fit through the exit door together.
2. Settling
Titanium dioxide particles are heavy.
Over time, they tend to settle in places where the ink is not moving enough, such as ink cartridges, ink bags, dampers, low-flow tubing, and flow dead zones.
When this happens, the local pigment concentration rises. That can create soft or hard sediment that becomes difficult to redisperse.
If those sediments enter the ink supply system, they can narrow the flow channels, much like narrowed or blocked arteries in the human body. Ink droplet size becomes less stable, ink flow becomes worse, and the risk of clogging increases.
3. Dispersant Failure
To help prevent aggregation, ink formulas include dispersants.
A dispersant is like putting a big inflatable swimming ring around each person at the cocktail party, making it harder for them to lock arms.
But this protection can weaken over time. Ink age, large temperature changes, and competitive adsorption between different additives can all reduce the effectiveness of the dispersant. Once that happens, titanium dioxide particles can get close to each other again and bind more tightly.
White ink is powerful because it contains titanium dioxide.
But titanium dioxide is also heavy, energetic, and eager to gather. That is why white ink is more prone to settling, aggregation, and clogging than ordinary color inks.
This is also why managing white ink is never just a matter of "use better ink" or "clean the printer more often." It requires good ink formulation, good ink movement, smart maintenance, and a mechanical system designed with the physics of white ink in mind.
