Liquid Highlighter Markers (Pack of 4) – Vibrant Colours, Smooth Flow, 3x Longer Lasting

Product Title

Soni OfficeMate Liquid Highlighter Markers | Chisel Tip Quick-Drying Highlighters | Water-Based & Eco-Friendly | Vibrant Fluorescent Colours | Pack of 4 | Non-Toxic, Long-Lasting | Suitable for Paper, Copies & Faxes (Thermal Paper) | Large Ink Capacity

Technical Specifications

Ink Composition: Water-based, non-toxic fluorescent vibrant ink with controlled viscosity for smooth discharge.
Tip Type: Precision-molded chisel tip with 1 mm (fine) and 4 mm (broad) marking capability.
Writing Length: Up to 350 meters of continuous marking (approximately 3× standard highlighter output).
Drying Time: Less than 5 seconds on standard 80 gsm copier paper (ambient 25 °C, RH 60%).
Bleed Resistance: ≤ 1 mm edge spread on standard office paper; optimized for low penetration.
Barrel Material: High-impact polypropylene (PP) body with matching PP cap, ventilated for safety.
Cap-Off Time: Maintains performance up to 24 hours without cap under controlled lab conditions.
Shelf Life: 24 months from manufacturing date under sealed storage (temperature 5 °C–35 °C).
Compliance: Conforms to ASTM D-4236, EN 71-3, and RoHS safety standards.
Available Set: 4 pcs (Orange, Yellow, Pink, Green).

Key Features

High Ink Reservoir Capacity: Delivers prolonged writing performance with uniform ink saturation and smooth flow control.

4.6 mm Precision Chisel Tip: Enables both fine and broad marking applications with consistent line geometry.

Water-Based Fluorescent Ink System: Produces high chromatic brilliance and excellent visual clarity under natural or UV light.

Optimized Rheological Balance: Maintains ideal viscosity and surface tension for uninterrupted capillary feed.

Quick-Drying Formulation: Provides instant surface fixation without smudging, bleeding, or feathering on absorbent media.

Superior Light Fastness: Retains fluorescence and color stability during prolonged exposure to sunlight or artificial illumination.

Non-Toxic, Solvent-Free Composition: Certified under EN-71, ASTM D-4236, and REACH standards for chemical safety.

Cap-Off Endurance: Preserves flow characteristics for up to six hours in uncapped condition at ambient temperature.

Thermal Stability Validated: Exhibits no viscosity drift or pigment precipitation after 15 days at 50 °C.

Polypropylene Structural Components: Chemically inert barrel, cap, and plug ensure dimensional stability and solvent resistance.

Eco-Responsible Construction: Utilizes recyclable packaging materials and conforms to environmental safety guidelines.

Physical Properties

Viscosity: Maintained between 9.9 and 12.1 cps at 25 °C (Brookfield method), ensuring stable capillary ink flow without flooding or skipping.

Surface Tension: Controlled within 33–35 dyn/cm for balanced wetting and smooth ink transfer on cellulose-based substrates.

Specific Gravity: Ranges from 1.10 to 1.12 g/cm³, providing uniform density and consistent flow through the nib filter assembly.

pH Level: Mildly alkaline, between 7.6 and 8.9, preventing corrosion of internal polymer components and maintaining dye stability.

Flow Behaviour: Exhibits Newtonian flow characteristics, ensuring constant viscosity across normal operating temperatures (20 °C – 30 °C).

Drying Time: Rapid surface fixation with minimal feathering or smearing on standard copier or bond paper.

Light Fastness: Excellent resistance to photodegradation; fluorescent intensity remains stable under sunlight or UV exposure.

Thermal Stability: Withstands continuous exposure at 50 °C for 15 days without phase separation, pigment precipitation, or viscosity drift.

Cap-Off Tolerance: Maintains writing performance for up to six hours at ambient temperature without tip clogging or drying.

Film Appearance: Dries to a uniform, semi-matte fluorescent layer with high optical reflectance and strong daylight visibility.

Paper Compatibility: Optimized for 70–90 gsm paper; no bleed-through or ink migration under normal marking pressure.

Physical Properties – Basic Colours

Viscosity and Flow Characteristics:
The Brookfield viscosity at 25 °C (measured at 60 rpm using a 61 LV spindle) ranges between 9.90 to 12.10 cps, ensuring a smooth and uniform ink flow. These values indicate consistent ink performance and reliable laydown during application.

Yellow: 9.90 cps

Green: 11.70 cps

Orange: 12.10 cps

Pink: 12.00 cps

Surface and Density Parameters:
The inks exhibit a surface tension between 33.00–35.00 dyn/cm, optimizing adhesion and spread on different surfaces. The specific gravity remains within 1.105–1.120 g/cm³, signifying balanced composition and pigment dispersion across all basic colours.

pH and Stability:
The formulations maintain a slightly alkaline pH level ranging from 7.65 to 8.90, ensuring long-term chemical stability and compatibility with writing instruments. Even under extended exposure—such as 8 hours of cap-off time at 25 °C or 15 days in an oven test at 50 °C—the inks retain their flow and consistency, showing “Flow OK” results and good cap-off performance.

Light Fastness and Durability:
All basic colours — Yellow, Green, Orange, and Pink — exhibit excellent light fastness, maintaining brightness and resistance to fading under prolonged light exposure. This makes the inks highly durable and suitable for both indoor and outdoor marking applications.

Performance and Compatibility

The ink formulation is specifically engineered for refillable highlighter systems and is compatible with both chisel-tip and bullet-tip configurations.
It is suitable for multiple substrate types, including plain paper, printed text, photocopies, and fax paper, without affecting print contrast or causing ink migration.
The product maintains non-smearing and fast-drying behavior across all common office paper weights.
It provides high chromatic intensity and optical brilliancy, ensuring strong visibility even on low-opacity papers.
The composition is non-toxic, water-soluble, and free from xylene or other volatile organic solvents.

Components & Materials

Nibs: Polyester (PE) / Acrylic

Filters: Polyester with polypropylene wrapping

Barrels: Polypropylene (PP)

Caps: Polypropylene (PP)

Nozzle & Plugs: Polypropylene

All polymer components conform to RoHS and REACH compliance standards for non-hazardous consumer stationery products.

Shelf Life and Storage Instructions

Shelf Life:
2 years from the date of manufacture (when unopened and stored properly).

Storage Instructions:

Store in a cool, dry, and well-ventilated area.

Keep ink containers tightly sealed when not in use to prevent evaporation.

Avoid direct sunlight, open flames, and sources of heat.

Do not freeze. If frozen, allow ink to return to room temperature before use.

Keep away from children and unauthorized users.

Shake well before use.

Store at room temperature (ideally 15–30 °C) for best results.

FAQs

Q 1. What type of ink is used in this highlighter?
A. It contains a water-based fluorescent ink formulation with controlled viscosity and surface tension for smooth, uniform flow and high chromatic brilliance.

Q 2. How long can the highlighter remain uncapped without drying?
A. The marker exhibits a cap-off endurance of up to six hours at 25 °C, maintaining full writing performance without nib hardening.

Q 3. Does the ink dry quickly on paper?
A. Yes. The ink provides instant surface fixation on standard paper, ensuring smudge-free and non-feathering performance.

Q 4. Is the ink safe for regular use?
A. Absolutely. The formulation is non-toxic, solvent-free, and fully compliant with EN-71, ASTM D-4236, and REACH safety standards.

Q 5. What is the product’s storage life and ideal storage condition?
A. The highlighter retains its physical and optical stability for up to 24 months when stored between 15 °C – 30 °C, away from direct sunlight or heat exposure.