- Core Principle: Prioritize High-Luminous-Efficiency Fluorescent Pigments
The “brightness” of fluorescent stickers essentially comes from the process where fluorescent pigments absorb external light (such as natural sunlight or fluorescent lighting) and convert it into visible light—this is called photoluminescence. Different types of fluorescent pigments vary greatly in luminous efficiency and brightness decay rate, making pigment selection the decisive factor for brightness. Currently, the market mainly offers organic fluorescent pigments and inorganic fluorescent pigments, with significant differences in performance.
Inorganic Fluorescent Pigments – The First Choice for High Brightness and Long Duration
Inorganic fluorescent pigments are based on inorganic compounds (e.g., sulfides like zinc sulfide, cadmium sulfide; aluminates like SrAl₂O₄, CaAl₂O₄), with activators such as europium (Eu) and dysprosium (Dy) added. They are the mainstream choice for high-brightness fluorescent stickers, featuring strong light absorption, high luminous intensity, and long afterglow duration—especially advantageous in low-light environments.
Key Performance Parameters: When purchasing, focus on initial luminous brightness (unit: mcd/m²) and afterglow duration (unit: hours). For example, high-quality aluminate pigments can reach 5000–10,000 mcd/m² (after 10 minutes under standard daylight exposure) with afterglow durations exceeding 10 hours (time for brightness to drop to 0.32 mcd/m²). In contrast, poor-quality sulfide pigments may only reach 1000–2000 mcd/m², with afterglow times under 3 hours.
Applications: Nighttime safety signs (fire escape indicators, stair treads), industrial equipment warnings, and outdoor emergency markers where high brightness and longevity are essential.
Notes: Some older cadmium-based sulfide pigments contain heavy metals—while reasonably bright, they pose environmental risks and have largely been replaced by cadmium-free aluminate pigments. Always check for heavy-metal-free certifications (e.g., RoHS compliance).
- Organic Fluorescent Pigments – A Low-Brightness, Short-Duration Secondary Option
Organic fluorescent pigments are made from organic compounds (e.g., fluorescent yellow, fluorescent red dyes) dispersed in resin carriers. They are vivid in color and cost-effective but have much lower luminous efficiency. Initial brightness typically ranges from 500–1500 mcd/m², with afterglow durations of only 1–2 hours, and they fade quickly under prolonged sunlight exposure.
Applications: Suitable only for low-brightness, temporary decorative use (e.g., children’s stickers, holiday decorations) or short-term indoor use—not recommended for functional purposes requiring high visibility.
Pitfall Warning: Some sellers confuse fluorescent colors with fluorescent luminescence. Organic pigments may look bright in daylight but do not glow in the dark. Always verify that the product offers photoluminescence rather than just vivid color.
Foundation: Select High-Transparency, Strong-Adhesion Substrate Materials
The substrate is the “carrier” for the fluorescent pigment. Its transparency, smoothness, and adhesion directly affect light absorption and brightness uniformity. If transparency is poor, even high-quality pigments won’t reach full potential. The main substrate types are plastic films and paper-based materials, with clear differences in brightness performance.
Plastic Film Substrates – The Best Carrier for High-Brightness Fluorescent Stickers
Plastic films offer high transparency and weather resistance, maximizing pigment brightness potential. Common materials include PET (polyethylene terephthalate), PVC (polyvinyl chloride), and OPP (oriented polypropylene). PET is generally the best choice:
PET: Light transmittance of 90–95% (close to glass), allowing maximum light penetration. It is smooth, temperature-resistant (-40°C to 120°C), stretch-resistant, and holds pigments well, with slow brightness decay (less than 10% loss after 6 months in normal lighting).
PVC: 80–85% transmittance—slightly lower than PET—but more flexible and cheaper, ideal for curved surfaces (e.g., cylindrical equipment labels). However, avoid PVC with plasticizers, which can leach under heat and cause pigment loss; opt for eco-friendly, plasticizer-free PVC (e.g., rigid PVC).
OPP: 85–90% transmittance but poor weather resistance—becomes brittle in cold and shrinks in heat. Suitable only for short-term indoor use (e.g., stationery stickers).
Paper-Based Substrates – A Budget Option for Low-Brightness Applications
Paper substrates (e.g., coated paper, kraft paper) have low transparency (often below 60%) and absorb moisture easily, reducing pigment brightness and durability. Even with high-quality inorganic pigments, brightness is typically 30–50% lower than PET-based products.
Applications: Only for dry indoor environments with low brightness needs (e.g., greeting card decorations). Not suitable for outdoor, humid, or long-term glowing applications.
Buyer Alert: Be wary of claims about “high-brightness paper fluorescent stickers”—the physical limits of paper make such claims misleading, often involving low-brightness organic pigments disguised as high-performance products.
