Solutions for Common Problems with White Ink

Without adequate and regular maintenance, white ink, which acts as the base layer in many digital printing applications, can lead to unexpected problems and disruptions in printing processes. In this blog, we will explore the characteristics of white ink to effectively address and resolve these issues.

Written by Procolored - Published on Nov 19, 2024

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8 minutes read

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Written by Procolored - Published on Nov 19, 2024

PASSAGE SUMMARY

1. Why White Ink is a Must in Specialty Printing
1.1 Ideal layer between substrates and graphic
1.2 Higher graphic reproduction
1.3 Branding and design consistency
2. Understanding the White Ink Property
3. The Commonly Seen White Ink Issues
3.1 Incomplete or missing white ink
3.2 Fading or grayish white ink
3.3 White lines with mixed colors on the testing page

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1. Why White Ink is a Must in Specialty Printing

First, let’s clarify what specialty printing entails. Unlike office printing, which primarily focuses on presenting text and simple graphics on paper, specialty printing involves producing prints with intricate designs and multiple colors on a variety of materials, such as fabric, metal, and acrylic.

With the rapid advancement of printing technology, specialty printing has evolved from traditional manual methods like screen printing to modern digital techniques, including Direct-to-Film (DTF), Direct-to-Garment (DTG), and Ultra-Violet (UV) printing, among others.

In most digital specialty printing methods, white ink serves as the base layer of the print. This brings us to the second question: why is a base layer necessary?

Specialty printing can be applied to a wide range of materials, each with different ink absorption properties. For instance, in fabric printing, cotton is known for its high water absorption capacity compared to other fabrics. Directly printing on cotton can result in incomplete graphics or noticeable color inconsistencies.

A base layer beneath the final print helps mitigate these negative effects caused by the substrate. But why is the base color specifically white ink?

printing front and back view - no white ink (left); with white ink (right)

image: youtube @Hai-Tech

1.1 Ideal layer between substrates and graphic

Almost all colored inks can cover the original substrate, but only white ink can serve as the perfect base layer without causing color deviation or blending. Graphics printed over colored layers, especially dark ones, will be negatively affected in terms of contrast, brightness, and opacity.

1.2 Higher graphic reproduction

Compared to colored backgrounds, especially dark ones, print colors on white ink appear much brighter and richer. The key reason for this lies in light reflection.

Light reflection plays a crucial role in how graphic colors are perceived. The more light that is reflected by the printed ink, the brighter and more vibrant the colors will appear. Colored backgrounds, particularly dark ones, absorb a significant amount of light, which diminishes the brightness and richness of the printed colors. In contrast, white ink reflects most of the light, allowing it to pass through the printed ink and enhancing the overall color contrast. This results in the highest color fidelity and the best presentation of intricate graphic details.

1.3 Branding and design consistency

Given the previously mentioned points, using white ink as the base layer provides a higher color standard and ensures a more complete reproduction. For printing orders of brand logos or visual designs, this guarantees consistent graphic colors, helping to create a professional and cohesive brand or corporate image.

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2. Understanding the White Ink Property

Since white ink plays such an important role in specialty printing, efficiently maintaining its performance and reducing malfunctions is crucial. One key solution is to fully understand its formulation.

Like colored inks, white ink is composed of binders, solvents, dispersants, and other chemicals to achieve the desired viscosity and liquidity. However, the main difference lies in the pigments or dyes used. White ink is often formulated with titanium dioxide (TiO₂) to ensure its opacity and brightness. TiO₂ is a white solid pigment that is heavier and larger than most organic pigments. It has a density of about 4.23 g/cm³, whereas many organic pigments used in colored inks have densities ranging from 1.0 to 2.0 g/cm³.

Given this formulation, white ink exhibits several specific properties:

Easier Sedimentation: As previously mentioned, the TiO₂ in white ink is much thicker and heavier than other pigments used in colored inks, leading to easier sedimentation if the ink is left unused for a while.

Shorter Drying Time and Higher Viscosity: While both white ink and colored inks use similar solvents and binders, the concentrations differ significantly. White ink contains fast-drying solvents and binders in higher concentrations, which means it dries more quickly and forms a firmer layer on substrates. However, this also means that white ink can evaporate and dry faster, leading to it firmly sticking to the printhead and potentially causing nozzle clogging issues.

3. The Commonly Seen White Ink Issues

3.1 Incomplete or missing white ink

Possible Reasons:Insufficient or expired white ink； Clogged printhead
Steps to Solve the Problem:
1) Check Ink Level: Ensure that the white ink is sufficient—ideally, it should be more than one-third full in the ink tank.
2) Check Expiration Date: Verify that the white ink is within its expiration period.
3) Exhaust Air from Ink Dampers: If the white ink is sufficient and valid, extract 5 ml of ink from each ink 4) damper to help remove any trapped air.
5) Restart the Printer: Turn off the printer, wait for a few minutes, and then turn it back on.
6) Extract Ink from Waste Ink Tube: After restarting, extract 5 ml of ink from the waste ink tube.
7) Perform Printhead Self-Cleaning: Use the printer's software to execute a printhead self-cleaning cycle.
8) Print a Test Page: Print a new test page to check if the issue has been resolved.
9) Contact Support: If the problem persists, contact our service team for further assistance.

3.2 Fading or grayish white ink

Possible Reasons: Sediment in white ink
Steps to Solve the Problem:
1) Shake the White Ink Bottle: Gently shake the white ink bottle to help dissolve any sediment that has settled at the bottom.
2) Extract Ink from the Cartridge: Extract more than 10 ml of ink from the cartridge to flush out any sediment.
3) Use New White Ink: If the above steps do not resolve the issue, consider replacing the white ink with a new bottle.
4) Contact Support: If the problem still persists, please contact our service team for further assistance.

3.3 White lines with mixed colors on the testing page

Possible Reasons: Clogged suction motor of the capping station; Waste ink flowing back to the nozzles
; Broken ink circuits in the nozzles
Steps to Solve the Problem:
Clean the Capping Station and Print Head Bottom Manually: Carefully clean the capping station and the bottom of the print head to remove any debris or dried ink.
Execute Print Head Self-Cleaning in the Software: Use the printer's software to run a print head self-cleaning cycle.
Print Test Graphics: Print some test graphics to help discharge any mixed ink from the nozzles.
Print a Test Page Again: Print a new test page to check if the situation has improved.
Contact Support: If the problem still persists, please contact our service team for further assistance.

About the Author - Simon

Simon has worked in inkjet printing industry for years. He has the rare ability to see print related issues from many perspectives. Witnessing the gradual development of digital printing especially inkjet printing, Simon knows better about what the users are looking for and how the new technologies will truly help big or small businesses.

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