Why digital UV inks need to be agitated (shaken)

When digital UV ink (used in UV printers) is not shaken regularly, several issues can occur that affect print quality and printer health. 

Here’s what happens:

1. Pigment Settling

UV inks — especially pigmented UV inks — contain solid color particles suspended in a liquid carrier.

• If not shaken, the pigments gradually settle at the bottom of the ink bottle or cartridge.

• The top layer becomes clearer and thinner, while the bottom becomes thicker and denser.

• When this unevenly mixed ink is used, color output becomes inconsistent, with faded or incorrect tones.

2. Clogging & Printhead Damage

• Settled pigments can form clumps or sludge over time.

• These particles may block the valve in the damper resulting in ink leakage.

• These particles may block the fine nozzles of the printhead, leading to banding, missing nozzles, or total blockage.

• UV inks are also photo-curable, so if particles or residue stick around, they can partially cure inside the printhead, permanently damaging it.

3. Uneven Curing and Adhesion

• Improperly mixed ink means the chemical balance is off.

• This can cause uneven curing under UV light — for example, some areas may remain tacky or overcured.

• Poor mixing also affects adhesion, causing prints to peel or scratch off easily.

4. Reduced Shelf Life

• When inks are left stagnant, the stabilizers and dispersants inside become less effective.

• The ink can separate permanently, even if shaken later.

• In severe cases, it becomes unusable and may need to be discarded.

Please find additional info on how to properly agitate UV ink via this link: https://support.mutoh.eu/en/support/solutions/articles/14000091069-how-to-properly-agitate-uv-ink