Why White Cleaning Doesn’t Work Well – Printer Cleaning Issues Part 13 ARTJET 2026

• When ink enters the Damper from the main ink bottle via the ink tube, it passes through the print head, flows to the captop, moves through the motor pump, and finally drains into the waste ink bottle.
• This article covers Why White Cleaning Doesn’t Work Well in the full ink supply problem series.
• This follows Part 1 Captop Lower Tube, Part 2 How to Replace the Captop, Part 3 Damper, Part 4 Pump Motor and Yellow Tube, Part 5 Captop and Head Position, Part 6 Aligning the Captop and Head Position, Part 7 When the Capping Station Level Is Not Correct, Part 8 Captop Surface Drying, Part 9 Degraded Ink Inside the Captop, Part 10 Time for Ink to Fill the Damper, Part 11 Ink Tube Burst, and Part 12 How to Replace a Motor Pump Tube.

Although it may vary by manufacturer, Color and Varnish inks are quite stable.

• Color and Varnish are only pumped or cleaned when there’s an occasional problem.
• If the printer was used the previous day, Color and Varnish don’t need cleaning the next morning.
• Nozzle condition is checked by simply printing a test image before proceeding with the actual print job.

However, White ink is different.

• White ink contains far more pigment than Color or Varnish to achieve proper density.
• Heavy particles mixed into the ink result in poor flow characteristics.
• For this reason, cleaning must be performed before printing to ensure proper White nozzle condition.
• The problem is that while White cleaning worked fine at installation, it gradually becomes less effective over time,
• and it takes longer for the nozzles to recover.

Why does this happen? We’ll explain what steps are needed to ensure proper cleaning.

The 600×900 size UV Printer has two White main ink tanks.

• The first tank is connected to White channels 1, 2, 3, and 4.
• The second tank is connected to White channels 5 and 6.
• For this reason, when cleaning fails, the problem rarely affects just one channel.
• It typically affects Channels 1, 2, 3, 4 or Channels 5, 6 as a group, with overall poor nozzle condition.

Refer to the photo below for how the White main ink tank, head channels, and nozzle patterns are connected.

To understand the root cause, you need to know what happens when you press the Print head cleaning button.

• Click the cleaning button in the software.
• The capping station moves down, allowing the head carriage to move. It touches the X-axis limit sensor once and returns to the home position (capping position).
• The capping station rises, pressing the captop against the underside of the head to create a seal.
• With the head and captop sealed, the motor pump starts rotating for the first time, extracting ink (1st pass).
• The motor pump briefly pauses, then rotates strongly again to extract ink (2nd pass).
• With ink now filling the captop, the capping station moves back down, releasing the seal between the head and captop.
• The motor pump runs for 8 seconds, transporting residual ink from the captop to the waste ink tank.
• The head carriage moves to the black wiper position, where the wiper cleans the underside of the head.
• After wiping, the head carriage moves to the opposite side of the X-axis and self-jets onto the spit pad.
• After jetting, the head carriage returns to the home position, and the capping station rises to seal the head, completing the cleaning operation.

If White cleaning isn’t working, the quickest solution is to replace the peristaltic pump tube (yellow tube) and Captop.

Motor pump tube replacement

• The official name is peristaltic pump tube, commonly referred to as the yellow tube.
• This tube is a consumable item that hardens and shrinks over time, thinning the tube walls.
• As the tube thins, it loses contact with the motor pump rollers, preventing ink from flowing smoothly.
• This causes the ink extraction process to fail.
• The UV Printer manufacturer recommends replacing it every 3 months.
• Based on our demo unit, the White motor pump is used frequently and should be replaced every 3 months for smooth White cleaning.
• Color and Varnish are used less frequently, so replacing every 6 months is sufficient.
• For detailed information on why replacement is needed, the performance difference, and how to replace it, click the link below.
• How to Replace a Motor Pump Tube

Captop replacement

• The captop, which creates a seal with the head, also loses effectiveness as its rubber blade becomes dull.
• The captop replacement cycle varies depending on printer settings. If cleaning isn’t working properly,
• the captop should be replaced along with the yellow tube.

Increasing head cleaning time

• If the ink extraction process isn’t working properly during cleaning, you can temporarily increase the suction time.
• In the software, go to Menu → Print Head Cleaning Setting → Ink Pump (millisec). The following window will appear.
• This corresponds to No.5, No.6, and No.8 in the cleaning chart above.
• Increasing the time for No.5 and No.6 extends the ink extraction duration, resulting in smoother cleaning.
• On our demo unit, increasing No.5 from 2,000 to 3,000 and No.6 from 3,000 to 5,000 resulted in improved White print head performance.
• However, you should first try replacing the peristaltic pump tube (yellow tube). Only use this method if the replacement alone doesn’t resolve the issue.
• No.8 is designed to drain remaining ink from the captop to the waste tank — there is no need to change it.

Increasing pump motor speed

• In addition to increasing the suction time through software, you can also increase the pump motor speed to improve ink extraction during cleaning.
• Turning the adjustment screw inside the blue block (marked by the red arrow in the photo below) clockwise increases the pump motor speed.
• Don’t turn it too far — rotating 45 to 90 degrees is sufficient to noticeably increase the motor speed.
• Again, replacing consumables is the top priority, and these adjustments are temporary workarounds.
• Once consumables are replaced, there is rarely any need to adjust the motor speed.

The reason White nozzle recovery doesn’t work well even after cleaning is that the ink extraction process isn’t functioning properly.

The ink extraction process fails because:

• The consumables — Captop and peristaltic pump tube — haven’t been replaced.
• If White cleaning isn’t working properly, the first step is to replace the yellow tube and Captop.

If spare consumables aren’t immediately available:

• You can temporarily improve cleaning by using software to increase the ink extraction time, or by increasing the motor pump speed to extract more ink.
• However, these methods will quickly lead to the same problem recurring — they are strictly temporary workarounds.