Captop surface drying - Printer Cleaning Issues Part 8 ARTJET 2026

Captop surface drying – Printer Cleaning Issues Part 8 ARTJET 2026

So far, I have summarized the information related to UV Printers below. If you click on the article, you will be taken to the link for related information.

I. Background information

We’re updating previous content.

The full text of Part 24 of the Ink Supply Issues series can be found through the link below.

24 articles on ink supply issues,

This article describes Captop-related issues highlighted in red in the full table of contents for ink supply issues.

When ink flows from the main ink bottle through the ink tube to the damper, it flows through the print head to the captop, then through the motor pump to the waste ink tank.

The first session covered the captop lower tube,
The second session covered how to replace the captop,
The third session covered the damper.
In the fourth hour, the pump motor and the yellow tube.
In the fifth hour, Captop and head position.
In the sixth hour, how to manually align the captop and head position.
In the seventh hour, we discussed the problems that arise when the capping station is not level and how to level it.

You can check the details by clicking the link.

Today, I’ll explain the issue where ink doesn’t flow into the waste ink tank when pumping, even though cleaning went smoothly before the holiday.

This is also the first thing to check when pumping or cleaning fails.

II. I think my white head is clogged _Captop surface drying

1. Problem symptoms

“I was using it without any issues until the Lunar New Year holiday, and it worked fine until the morning after the holiday, but then suddenly in the afternoon, the white nozzle stopped working.”

It worked fine until the morning? This part made troubleshooting confusing.

2. Problem solving

First call

“I loaded the ink five times, cleaned it five times, and did a test print with the ARTJET TEST image in full white, but the white doesn’t come out.”

“When you load (pump) the ink, does the ink flow out smoothly without air bubbles?”

“The space is limited, so I didn’t check that far. I’ll remove it and check the waste ink tank to see if the ink load (pumping) is working properly.”

Second call

“At first, only a few bubbles came out, but now nothing comes out.”

“Move the head carriage to the left, pour some alcohol into the captop, and try reloading (pumping) the ink. If you don’t use it for a long time, the white captop sometimes dries out, and ink doesn’t come out when you reload (pump) it.”

“What is a captop? And how do I move the head carriage to the left?”

“Press the left arrow button in the software. The head carriage will move to the left. Once it gets to a certain point, press it again. It will stop. Then, where the head carriage was, the square with a black border is the captop. Pour enough alcohol into the white captop.”

“It seems like this is my first time pressing the left arrow… lol. I’ll give it a try.”

Third call

“Sir, is the ink loading (pumping)?”

“It seems like alcohol is coming out at first, but nothing comes out after that. Could the white head be clogged due to lack of use during the holiday?”

“The head isn’t clogged, but rather due to a lack of ink supply. Please repeat this process a few times.”

And the whole KakaoTalk message

3. Cause of the problem

The cause of the problem is as follows:

In the capping state, the captop and the print head are sealed, preventing air from entering. However, after being left for a long period (during the holidays), the seal was broken, exposing the print head to air.
The white ink on the print head surface gradually dries and hardens as it is exposed to air.
Because the print head surface is hardened, ink does not flow out of the print head during the cleaning pump.

Pouring alcohol onto the print head and trying it once did not resolve the issue.

When alcohol was poured once, the dried ink on captop surface was removed, and the alcohol flowed out.
During the previous five ink load (pumping) cycles and five print head cleaning cycles, all lines from the end of the print head to the waste ink tank were filled with air instead of liquid (ink).
Ink load (pumping) does not function properly when the lines are filled with air, and instead continuously flows liquid while still filled.
In this case, several repetitions of the alcohol cycle are required to fully discharge the ink.

Please note that if cleaning or pumping is not working properly, it’s best to replace the captop and yellow tube (peristaltic pump tube) with new ones before inspecting the unit for the problem.

Since there are so many variables at play when cleaning or pumping is not working, replacing the captop and yellow tube with new parts will help resolve the issue quickly and identify the cause.
The video below shows the motor pump operating before and after replacing the yellow tube.
Click here to see a comparison video.
Surprisingly, there are many cases where cleaning and pumping issues can be resolved by replacing just two parts.

III. Causes and precautions for head clogging _Captop surface drying

1. Ink viscosity of industrial heads and other Epson series heads

For industrial inkjets, industrial heads from Konica, Dimatix, and Rioch are used.

Industrial heads can jet ink with a viscosity of approximately 10 cp.
The ink used in industrial heads has a viscosity of approximately 20 cp at room temperature, but when heated to 40-50°C by a heater within the head, the viscosity drops to 10 cp.
Because industrial ink has a high viscosity, it can sometimes solidify inside the head if left unused for a long period of time.
This is why the company representative was concerned, saying, “Is the head clogged?”

UV printers using Epson heads have a lower risk of white ink clogging compared to industrial heads.

Epson heads operate multiple channels and, because they are inexpensive, do not have internal heaters.
This means that ink used in Epson heads must have the same viscosity even when jetting at room temperature.
For Epson heads to jet without problems, the ink viscosity must be below 7 cp.
The lower the viscosity, the thinner the ink, like water. Therefore, the risk of ink clogging the head itself is lower compared to industrial heads.
If you look closely at the photo below, you can see a faint pattern, although the entire nozzle is not visible.
This is more likely a symptom of a nozzle clog than a problem with ink supply, preventing the nozzle pattern from being printed.

2. Cases of head blockage and precautions

The nozzles on the head can be clogged by UV light.

If you don’t know the difference between a head and a nozzle, click here.
During printing, when the nozzle under the head is repeatedly exposed to UV light, there is no problem at first, but if it receives enough UV light to harden the ink, it hardens the ink in the nozzle in an instant.
When the UV ink hardens the ink in the small nozzle hole, the ink then starts a chain reaction with each other, hardening the ink inside the nozzle as well.
Because of this, once a nozzle is clogged by UV light, it is not easy to revive it by cleaning only the nozzle surface.

Industrial print heads can clog their nozzles due to the heat generated by the internal heater.

Ink used in industrial print heads such as Konica and Dimatix has a viscosity of 20 cp at room temperature.
20 cp is too high for inkjet print heads to jet.
The ink is heated to 40-50°C using an internal heating device, reducing the viscosity to 10 cp before jetting.
If the print head is continuously heated for an extended period without jetting, the ink remaining at the nozzle tip will harden due to the heat.
Because the ink has solidified inside the nozzle, even ink loading (pumping) and cleaning procedures will not easily clear the clogged nozzle.

Since Epson printer heads don’t heat up, the first thing to watch out for is UV light reflection.

In particular, when printing on tall materials, the UV reflection angle increases, resulting in more UV light hitting the head, potentially causing the entire head to clog instantly.
When printing on tall materials, place similarly tall materials next to the print material to prevent the UV reflection angle from increasing.
In fact, an incident occurred in May 2020 when three heads clogged while continuously printing 70mm materials on equipment installed.

The second thing to watch out for is that the white ink will harden if left unused for a long period of time.

The white main ink tank must have a device that stirs the ink.
If the ink isn’t stirred, the white pigment will sink to the bottom and gradually harden.
By the same principle, if the printer is left unused for approximately a month, the white pigment in the ink tube may sink and harden.
Similarly, white ink may harden within the damper or head nozzle.
For this reason, even if there is no printing, you should perform a white cleaning, pumping, and test print once a week or every two weeks.
No matter how busy you are, it’s best not to leave the equipment unused for more than a month.

IV. ARTJET UV Printer

One thing I’ve noticed after five years of sales and maintenance of ARTJET UV printers is that troubleshooting data is second only to product stability.

All products have issues, whether they’re caused by actual equipment problems or consumer error. Product stability hinges on how quickly and easily you can resolve those issues.

ARTJET compiles all troubleshooting data.

You can see the product print quality by clicking here.

Click here for ARTJET pricing and terms of sale. The exterior design has changed.

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INKJET UV Printer & Laser Cutting Machine