How to Fix Thick Pad Printing and Screen Printing Inks?

What to Do When Pad Printing & Screen Printing Inks Become Thick? Ink Fluidity & Dilution Adjustment Guide

In pad printing and screen printing processes, ink viscosity and fluidity directly affect print quality. When ink is stored for a long time or repeatedly exposed to air after opening, solvent evaporation, pigment settling, storage environment, and temperature changes can cause the ink's fluid state to differ from its original condition.

When you notice that pad printing ink is too thick, screen printing ink does not flow smoothly, or the ink drying speed has changed, it does not necessarily mean the ink is unusable. In fact, you can first check the ink state, thoroughly stir it, and then adjust it with suitable solvents based on the specific printing process.

This article explains the basic adjustment methods for pad printing and screen printing inks from the perspectives of ink fluidity, viscosity, solvent selection, and printing processes.

 

Why Does Ink Fluidity Decrease After Long-Term Storage?

Ink is not composed solely of pigments; it consists of pigments, resins, solvents, and other functional additives. After prolonged storage, the ink state can be affected by multiple factors.

• Solvent Evaporation: Solvents in the ink may evaporate to varying degrees over time depending on the sealing condition, increasing ink viscosity.

• Pigment Settling: Standing still for a long time may cause pigments or solid components to settle, resulting in uneven consistency between top and bottom layers.

• Storage Temperature: Ambient temperature affects ink viscosity and fluidity; lower temperatures typically reduce ink fluidity.

• Opening & Sealing Status: Repeatedly opening the container increases solvent exposure to air, which can also impact ink performance.

• Lack of Stirring Over Time: Inks left standing need re-mixing to restore an even distribution of components.

Therefore, when determining whether an ink is suitable for use, you should not rely solely on the manufacturing date or storage duration, but rather inspect the actual ink condition and verify through test printing.
 

How to Adjust Thick Pad Printing Ink?

Pad printing requires ink to maintain appropriate fluidity during doctoring on the printing plate/cliché and transferring via the silicone pad. If the ink viscosity is too high, it may compromise ink pick-up, transfer efficiency, or image integrity.

Before use, it is recommended to thoroughly stir the ink to re-disperse settled pigments and components uniformly. After verifying the ink condition, add appropriate solvents according to actual printing requirements.

Pad printing applications generally pair well with fast-drying solvents to maintain suitable drying speeds during transfer. However, the final choice should still be tested based on printing speed, ambient temperature, pattern size, and specific ink characteristics.
 

How to Adjust Thick Screen Printing Ink?

Screen printing operating conditions differ from pad printing. In screen printing, the ink needs to maintain appropriate fluidity and open time on the mesh screen to pass smoothly through the mesh holes and form a stable ink film thickness.

If screen printing ink dries too quickly, it may gradually dry on the screen, causing poor ink passage or mesh clogging. Therefore, screen printing is typically paired with slower-drying solvents to help maintain adequate working open time.

Actual adjustments must still account for mesh count, image area, squeegee speed, printing speed, ambient temperature, and humidity.
 

What Percentage (%) Should Ink Be Diluted?

There is no single fixed dilution ratio that applies to all printing conditions. However, in practical operation—taking 110GK as an example—you can start with approximately 20–30% as an initial baseline reference and make gradual adjustments based on actual ink fluidity and printing results.

It is recommended not to add large amounts of solvent all at once. Instead, adopt a method of adding small increments, mixing thoroughly, test printing, and fine-tuning step by step. Note: Recommended initial ratios vary across different ink models and depend on current ink conditions. Different ink properties also require different additives.

For Example:

1. Inspect the ink appearance and storage condition first.

2. Thoroughly stir the ink before use.

3. Choose suitable fast-drying or slow-drying solvents based on pad printing or screen printing processes.

4. Start with a baseline ratio of about 20–30% (for inks with better natural fluidity, you can test starting from 10%).

5. Mix thoroughly and perform actual test printing.

6. Fine-tune step by step according to ink fluidity, drying speed, and print results.
    

Thinner ink is not always better. Adding excessive solvent may alter color density, opacity, edge definition, film thickness, or adhesion performance. Therefore, aim for a balanced state that completes printing stably rather than simply pursuing lower viscosity.
 

What Is the Difference in Solvent Selection Between Pad and Screen Printing Inks?

The same ink series may require different drying speeds across different printing processes. Because ink transfer methods, printing speeds, and operating times vary between pad and screen printing, solvent selection must match the specific process.

Difference Between Pad Printing and Screen Printing

The above serves as a general operational guideline. Actual solvent selection and addition ratios should still be tested based on ink model, substrate material, screen/plate conditions, and shop-floor environment.
 

Over-Diluting Ink Can Also Cause Printing Problems

When encountering thick ink, many people immediately think to "add more solvent." However, over-dilution can cause equally serious print quality issues:

• Reduced color concentration
• Decreased opacity/hiding power
• Altered ink film thickness
• Potential ink bleeding along pattern edges
• Unpredictable drying time changes
• Compromised adhesion and ultimate durability

Therefore, the true goal of ink adjustment is to achieve a perfect balance among viscosity, fluidity, drying speed, and printing conditions.
 

What Should You Check Before Using Long-Stored Ink?

For pad or screen printing inks stored over extended periods, perform a basic inspection prior to full production runs:

• Check if the container is completely sealed.

• Observe if the ink exhibits severe clumping, abnormal hardening, or other anomalies.

• Check for noticeable layering or heavy pigment settling.

• Stir thoroughly and check if the ink restores to a homogeneous state.

• Adjust solvents according to the specific printing method.

• Conduct a small-area test print.

• Verify color, fluidity, drying speed, and adhesion strength.

If the ink still shows obvious abnormalities after stirring and proper adjustment, avoid putting it directly into mass production and further evaluate ink condition and suitability.
 

Different Substrates Require Different Ink Adjustments

Even when using the exact same ink, varying substrate surface properties can lead to different print results. Materials such as glass, metal, PC, PA, PP, PE, PVC, and coated surfaces differ in surface energy, additives, mold release agents, and pre-treatment states—all of which affect ink adhesion and print quality.

Thus, after adjusting ink fluidity, always conduct tests on the actual material. Particularly for plastics like PP and PE, pre-treatment conditions must be verified. If release agents, anti-static additives, or slip agents exist on the surface, adhesion strength may also be impacted.
 

RUCOINX 110GK Is Suitable for Pad Printing and Screen Printing

German RUCOINX 110GK is a 2-component multi-purpose printing ink applicable to both pad printing and screen printing depending on process requirements. This series features high gloss, excellent hiding power, mechanical resistance, and chemical resistance—suitable for glass, metal, coated surfaces, and various plastic substrates.

Across different printing processes, it can be adjusted with appropriate solvents as needed—for example, tweaking toward faster drying for pad printing or slower drying for screen printing, followed by gradual fine-tuning based on test results.

If you are looking for pad printing ink, screen printing ink, glass ink, metal ink, or plastic ink, feel free to check the color options and specifications of the RUCOINX 110GK series.

FineCause RUCOINX 110GK Ink Original Packaging Clearance Sale

FineCause currently offers a clearance sale on the full RUCOINX Eco-Friendly 110GK Ink series, including various printing colors, white ink, CMYK process inks, clear varnish, gold, and silver inks in original packaging inventory.

All items are now offered at up to 70% off original packaging clearance pricing (All cans are opened and inspected for quality before shipment)., ideal for users with pad printing, screen printing, sampling, testing, or short-run production needs.

Because different ink items, storage statuses, substrates, and process conditions vary, we still recommend inspecting ink condition and performing test prints prior to actual production.

👉 FineCause Ink Clearance Zone | RUCOINX Eco-Friendly Ink 110GK Full Series Original Packaging Clearance Up to 70% Off (All cans are opened and inspected for quality before shipment).

To confirm ink colors, substrate suitability, stock quantities, or specific printing requirements, please contact FineCause for professional technical evaluation.
 

Frequently Asked Questions (FAQ)

Q1: Can pad printing ink that has thickened over time still be used?

Ink stored for long periods may experience viscosity changes due to solvent evaporation, settling, or storage conditions. It should not be judged unusable based solely on storage duration. It is recommended to inspect the ink state, stir thoroughly, adjust with solvents according to actual printing conditions, and perform test prints.

Q2: What should be added if screen printing ink is too thick?

For screen printing, select an appropriate slow-drying solvent compatible with the ink system. Check the ink model and printing conditions first, then begin testing with a baseline ratio of about 20–30% rather than adding a large amount of solvent at once.

Q3: Can pad printing ink and screen printing ink use the same type?

Some multi-purpose ink systems can be applied to both pad printing and screen printing. However, because the two processes require different drying speeds and ink fluidity, appropriate solvents and adjustment methods must be chosen for each process. RUCOINX 110GK is a 2-component multi-purpose ink that can be applied to both pad and screen printing according to operational needs.

Q4: Is thinner ink always better?

No. Over-diluting ink can alter color density, opacity, film thickness, drying speed, and adhesion performance. Ink adjustment should aim to match the fluidity and drying speed required by the actual printing process.

Q5: Does an older manufacturing date mean the ink definitely cannot be used?

You cannot judge ink usability solely by the manufacturing date. Actual ink condition depends on storage environment, sealing condition, and product characteristics. Always inspect the ink state and perform actual print testing prior to use to confirm whether it meets current operational requirements, avoiding unnecessary waste of usable ink.