MINI GUIDE - Water-Based Inks

🎯 Water-based inks represent the sustainable, high-performance benchmark for soft-touch textile printing. Unlike plastisol inks, they offer an unnoticeable hand feel, high breathability, and full compliance with environmental standards (ZDHC/OEKO-TEX). However, rapid water evaporation demands strict control over the shop floor environment, mesh selection, and thermal curing cycles to prevent screen clogging.

KEY PARAMETERS

Operational Print Variables

Parameter	Primary Effect	Operational Tip
Ambient Humidity	Prevents ink drying inside mesh openings.	Maintain print room relative humidity at 55%–65% RH.
In-Tub Viscosity	Controls ink shearing and edge definition.	Target: $25,000 - 35,000 \text{ mPa}\cdot\text{s}$; dilute max 3-5% with DI water.
Mesh Selection	Regulates ink deposit and water evaporation during stroke.	Use 230–305 tpi (90–120 threads/cm) High-Tension/Low-Elongation mesh.
Retarders & Wetting Agents	Slow down surface evaporation on press.	Add 1.5%–3% water-soluble retarder for long production runs.

3 GOOD HABITS

Keep the matrix flooded: Always perform a generous flood stroke immediately after printing.

Mist demineralized water or retarder over screen edges during press pauses.

Use water-resistant SBQ or photopolymer emulsions treated with a chemical hardener.

OPERATIONAL CHECKLIST

Essential Process Controls

Check	Frequency	Responsible	Action if non-compliant
RH and Temperature Log	Every 2 hours	Print Operator	Engage ultrasonic humidifiers if RH drops below 50%.
Screen Emulsion Condition	Pre-press setup	Screen Maker	Apply water-resistance hardener for production runs over 1000 pcs.
Post-pause Screen Cleaning	Immediate	Print Operator	Wipe gently with damp sponge; avoid harsh solvents on wet ink.
Dryer Curing Audit	Batch start	QA Technician	Verify actual ink film temp ($160^\circ\text{C}$ for $3 \text{ min}$) using thermo-strips.

BASIC INDICATORS

Performance Targets

Indicator	Target
Flash Cure Surface Drying	3–5 seconds at 110°C–120°C (water evaporation only)
Full Final Curing	160°C for 180 seconds in forced-air dryer
Dark Garment Opacity	Achievable in 2 strokes (High-Opacity Ink or Underbase White)
Wash Fastness Rating	Grade 4/5 after 5 domestic wash cycles at 40°C (ISO 105-C06)

USEFUL TIPS

Best Practices

Tip	Benefit
Utilize high-CFM forced-air dryers instead of pure IR radiators.	Water evaporation requires active hot air movement before resin crosslinking occurs.
Add a cold-cure crosslinker (1–2%) when printing on synthetic fabrics.	Enhances wash resistance while enabling lower curing temperatures (130°C).
Measure residual moisture in garments prior to final packaging.	Prevents mildew growth and dye migration in sealed boxes.
Use sharp-edged triple-durometer squeegees (70/90/70 ShA).	Ensures clean shear without depositing excess water that causes dot gain bleeding.

💡 REMEMBER

"With water-based inks, curing is not just applying heat, but fully evaporating moisture before the resin can crosslink."

👉 Discover the BASIC – ADVANCED – PROFESSIONAL Guides from the Screen Printing Master Map.

NOTES

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