- Anyone printing white text on paper and finding it blurry or unclear
- Anyone noticing that printing color first then white gives cleaner results than white first
- Anyone wanting to understand the difference between Single Leave and Single Return print options
- ㅕAnyone looking for a solution when the material absorbs ink too quickly
- Switching to Single Return improves sharpness but lowers color density — balance the two based on your print requirements
- If the material absorbs ink extremely fast, Single Return alone may not be enough — combining with a Varnish spot layer is recommended
- When using a Varnish spot, slight feathering (blur) on the Varnish edges can help white ink adhere more cleanly
- Results vary depending on the surface tension and absorbency of the paper — always run a test print before full production
- White text blurry on paper → ink is being absorbed into the paper before it cures
- Step 1: switch from Single Leave to Single Return → ink cures immediately as it fires, reducing spread time
- Step 2: if still blurry → add a Varnish spot layer under the white → white lands on varnish, not bare paper
- Why color-first then white works: color ink creates a surface layer that prevents white from being absorbed
- Varnish spot with slight feathering → white adheres cleanly without being absorbed
I. Problem Symptoms _ Paper That Absorbs Ink
This is a machine installed at the Hongik University Sejong Campus Industry-Academic Cooperation Group in June. The elevator was too small for the equipment, so the X-axis was turned and the machine was carried up using the staircase.
“Just a moment.” — KakaoTalk messages can sometimes be missed when working on other things.
“Just a moment, let me check the photo. Is the material paper?”
II. Troubleshooting _ Paper That Absorbs Ink
“Are you currently using Single Leave?”
“Try switching to Single Return first — it should improve things.”
“If Single Return doesn’t fully fix it, set up a Varnish spot the same way as the white spot and print them together.”
“If it still isn’t sharp enough, don’t suppress the Varnish spot edges — add a slight feather (blur) instead. That should do it.”
III. Root Cause _ Paper That Absorbs Ink
Large-format UV printers typically have LED lamps on both sides of the head carriage. Smaller UV printers — like ARTJET — prioritize print quality over speed, so the LED lamp is mounted on one side only, similar to Roland LED printers.
Single Leave
Viewed from the front: ink fires as the head carriage moves right to left. On the return pass, no ink is fired — instead, the LED cures the ink that was just laid down. There is a short delay between ink landing and the LED reaching it, and during that window the ink behaves like a liquid and spreads across the material.
- How much it spreads depends on the surface tension of the material
- More spreading = deeper color, but sharpness decreases
- On ink-absorbing paper: ink is absorbed into the material the moment it lands — sharpness drops and color density is lost
Single Return
Viewed from the front: ink fires as the head carriage moves left to right, and the LED lamp mounted beside the head cures the ink immediately as it fires. Because ink is cured almost instantly, the spreading time is significantly shorter.
- Sharpness is better since ink has almost no time to spread
- Color density is lower because the ink doesn’t spread
- On ink-absorbing paper, Single Return produces sharper results than Single Leave
- However, if the material absorbs ink extremely fast, even Single Return may not be enough
This is exactly why — and the Varnish spot uses the same principle.
- First, a transparent Varnish layer is printed on the ink-absorbing paper
- The white ink then lands on the cured Varnish surface — not directly on the bare paper
- Because white ink is no longer being absorbed into the paper, the text prints cleanly and sharply
- This is the same reason printing color first then white works — the color layer acts as a barrier that prevents white from being absorbed
V. ARTJET UV Printer
