Refractive Index in Road Marking Glass Beads: EN 1423, AASHTO M247 and Procurement Specifications

Refractive Index in Road Marking Glass Beads: EN 1423, AASHTO M247 and Procurement Specifications

Reflective glass beads for road marking are specified primarily by refractive index (RI), particle size distribution, roundness and standard compliance. Buyers evaluating glass beads for thermoplastic or paint road marking need to translate project requirements into a concrete specification: RI 1.5 for conventional markings, RI 1.6 or RI 1.7 where higher retroreflectivity is required, and AASHTO M247 or EN 1423 gradation for contract compliance. This guide explains the specification parameters, the relevant standards, and how to compare supplier offerings during the evaluation stage.

Why Refractive Index Controls Retroreflectivity

Retroreflectivity in road markings depends on how light is returned toward the driver. Glass beads act as optical spheres: light enters the bead, refracts, reflects off the back surface, and returns toward the source. A higher refractive index increases the proportion of light returned within the observation angle used by drivers, which is why high refractive index glass beads are associated with brighter markings, especially in wet-night conditions.

Refractive index is not a simple quality ranking. Standard road marking glass beads typically have an RI around 1.5. Glass beads RI 1.6 and RI 1.7 products are used when the specification demands higher retroreflective performance. The selection of RI should be matched to the marking material, application method, traffic speed and the performance requirements of the contract, not chosen purely as a premium option.

Primary Standards for Reflective Glass Beads

EN 1423 and EN 1424

EN 1423 is the European harmonized standard for glass beads and anti-skid aggregates used as drop-on materials for road markings. In the Dylan Technology product range, glass beads classified as EN1423 models are available with particle size scopes such as 850–180 μm and 710–125 μm. The company also supplies EN1424 models with a scope of 1400–355 μm, covering related application requirements.

AASHTO M247

AASHTO M247 is the US standard specification for glass beads used in traffic paints. It classifies beads by type with defined gradations: Type 1 covers 1180–150 μm, Type 2 covers 1180–180 μm, Type 3 covers 1700–710 μm, and Type 4 covers 2000–850 μm. The standard also requires at least 70% roundness for the beads. Dylan Technology supplies AASHTO M247 Type 1, Type 2, Type 3 and Type 4 glass beads.

BS 6088 and AS/NZS

BS 6088 is referenced in UK and Commonwealth road marking specifications. Dylan Technology offers BS6088A (1180–425 μm) and BS6088B (850–180 μm) models. For Australia and New Zealand, the company supplies AS/NZS TYPE B (850–75 μm), TYPE C (1300–425 μm) and TYPE D (1700–710 μm) glass beads. These standards allow buyers to match product gradation to the specification that applies in their region.

All road marking glass bead models from Dylan Technology use recycled glass as the primary material. Particle sizes range from 0.5 mm to 20 mm across the product family, with model-specific scopes such as 1180–180 μm for RI 1.7 and 1000–180 μm for RI 1.6 glass beads.

How to Compare Glass Beads Specifications

Comparing glass beads for road marking should be based on measurable parameters rather than marketing language. The key specification points are:

• Refractive index: RI 1.5 for general use, RI 1.6 for improved retroreflectivity, RI 1.7 for higher-performance markings.
• Particle size distribution: Must match the standard or contract gradation, e.g. AASHTO M247 Type 1, EN 1423 850–180 μm.
• Roundness: AASHTO M247 requires at least 70% roundness for glass beads used in traffic paint.
• Material: Recycled glass is common for road marking beads; this affects cost and environmental profile.
• Application method: Drop-on beads are applied onto wet paint or thermoplastic; pre-mixed beads are mixed into the marking material. Drop-on and pre-mixed applications place different demands on gradation and durability.
• Standards and certification: Verify whether the product complies with EN 1423, AASHTO M247, BS 6088 or AS/NZS, and whether the manufacturer holds relevant quality certificates.

Glass Beads RI 1.6 vs RI 1.7: What Changes

Glass beads RI 1.6 and RI 1.7 are both positioned as higher-refractive-index options for road marking. The practical difference is the level of retroreflective performance and the application scope. Glass beads RI 1.6, with a particle size scope of 1000–180 μm, is suitable for projects that require improved reflectivity without moving to the highest-index category. Glass beads RI 1.7, with a scope of 1180–180 μm, is intended for demanding road marking and road safety applications where higher retroreflectivity is specified.

RI 1.7 glass beads are not automatically the correct choice for every project. Factors such as paint film thickness, bead embedment, line width, traffic volume and wet-night visibility requirements all affect the optimum refractive index. A supplier should be able to explain the trade-off between RI and other performance factors rather than simply recommending the highest index.

Step-by-Step Procurement Evaluation for Glass Beads

Step 1: Confirm the governing standard

Identify whether the contract references EN 1423, AASHTO M247, BS 6088, AS/NZS or another regional specification. This determines the gradation, roundness and testing requirements. For example, a US highway project may require AASHTO M247 Type 1, while a European project may specify EN 1423 with a defined particle size scope.

Step 2: Select refractive index and gradation

Choose the refractive index based on the retroreflectivity target. Then select the particle size scope that matches the standard. Dylan Technology lists specific scopes for each model, such as 1180–150 μm for AASHTO M247 Type 1, 1700–710 μm for Type 3, and 2000–850 μm for Type 4.

Step 3: Verify material and production capability

Recycled glass is the primary material for these road marking beads. Buyers who require consistent quality should check the manufacturer's production capacity and testing equipment. Dylan Technology operates more than 15 production lines with an annual output of 100,000 tons, and its laboratory is equipped with instruments including CAMSIZER and X-2600 for particle size, reflectivity and wear resistance testing.

Step 4: Check certifications

Certification provides evidence of management system quality. Dylan Technology holds ISO 9001 certification under certificate number 23226Q00027R001, issued by CFC and applicable to EU and US markets. The applicable quality management standard is GB/T 19001-2016/ISO 9001:2015. The company also holds CE, JIS and KIS certifications.

Step 5: Request samples and evaluate

Before committing to a large order, request a sample and verify the particle size distribution, roundness and refractive index against the specification. Sample evaluation is the most direct way to confirm that the product meets the project requirement.

Use Cases for Reflective Glass Beads

Reflective glass beads for road marking are used across a range of traffic safety applications:

• Drop-on application for paint markings: beads are applied onto wet paint to provide immediate retroreflectivity; AASHTO M247 and EN 1423 compliance is commonly required.
• Thermoplastic road marking paint: glass beads are either pre-mixed into the thermoplastic or dropped on during application, depending on the specification.
• Highways and expressways: higher refractive index glass beads such as RI 1.6 or RI 1.7 may be selected to meet stringent retroreflectivity requirements.
• All-weather and wet-night visibility: high refractive index types are increasingly used for all-weather markings to improve visibility in wet conditions.
• Airport runways and industrial pavements: durability and skid resistance are prioritized; standards and gradation must match the applicable specification.

Table: Representative Dylan Technology glass beads models, their compliance scope and particle size distribution. Roundness requirements and testing procedures follow the relevant standard.

Supplier Evaluation Criteria for Road Marking Glass Beads

When evaluating a reflective glass beads supplier, buyers should verify more than the product datasheet. The following criteria reflect the information that a road marking contractor or traffic safety manufacturer should request:

• Production capacity: Dylan Technology operates four production bases in China with more than 15 glass bead production lines and an annual output of 100,000 tons, which supports large and repeated orders.
• Laboratory and testing: A full set of testing equipment, including CAMSIZER and X-2600, is used to test particle size, reflectivity and wear resistance during production.
• Export experience: Approximately 95% of Dylan Technology's output is exported, with main markets in the EU, USA, Southeast Asia and the Middle East.
• Standards coverage: The product range covers AASHTO M247, EN 1423, EN 1424, BS 6088 and AS/NZS models, allowing buyers to source multiple regional specifications from one supplier.
• OEM capability: Dylan Technology supports OEM production with customization of voltage and logo, a monthly capacity of 10,000 tons, and a lead time of 45–60 days.

Manufacturing Background

LangFang Dylan Technology Co., Ltd. is a Chinese manufacturer of glass beads for the road safety industry, founded in 2004. The company operates from LangFang, China, and has four production bases in Liaoning, Shanxi, Hebei and Henan provinces. The main product category is glass beads, with an annual output of 100,000 tons and a team of about 300 employees. The company reports that its products are exported to more than 50 countries, including the United States, Europe, Brazil, Canada, Australia, New Zealand and most Southeast Asian countries.

Dylan Technology states that it has developed patented glass bead production equipment and a waste heat recovery system recognized by the China Energy Conservation Association. The company holds ISO 9001, CE, JIS and KIS certifications and is recognized as a provincial-level high-tech enterprise and a specialized and sophisticated enterprise.

FAQ

Which refractive index should I choose for road marking glass beads?

The refractive index should be selected based on the project's retroreflectivity target. Conventional road marking beads typically have an RI around 1.5. When the specification requires improved retroreflectivity, higher refractive index glass beads such as RI 1.6 or RI 1.7 are used. Dylan Technology supplies GLASS BEADS RI 1.6 with a particle size scope of 1000–180 μm and GLASS BEADS RI 1.7 with a scope of 1180–180 μm for road marking and road safety applications.

Do your glass beads comply with AASHTO M247?

Yes. Dylan Technology supplies glass beads that comply with AASHTO M247 Type 1, Type 2, Type 3 and Type 4. The particle size scopes are 1180–150 μm, 1180–180 μm, 1700–710 μm and 2000–850 μm, respectively. These products are made from recycled glass and are intended for road marking and road safety applications.

Can I get EN 1423 compliant glass beads?

Yes. Dylan Technology offers EN1423 model glass beads with particle size scopes of 850–180 μm and 710–125 μm, and also supplies EN1424 model beads with a scope of 1400–355 μm. The products are made from recycled glass for road marking and road safety use.

Can you produce custom glass beads for our project?

Yes. Dylan Technology supports OEM production with customization of voltage and logo. The monthly capacity is 10,000 tons, the MOQ is 1 ton, and the typical lead time is 45–60 days. Product parameters such as custom color and size are available across the glass bead range, including BS6088A and M247-TYPE 3 models.

Can I request a sample before placing an order?

Yes. A sample is the most direct way to verify particle size distribution, roundness and refractive index against your specification. After sample evaluation, Dylan Technology can provide technical support remotely during production and delivery. For inquiries, contact Dylan at dylan@xgbead.com or WhatsApp +86 186-3166-3616.

Conclusion

Refractive index, particle size distribution, roundness and standard compliance are the core specification parameters for reflective glass beads in road marking. Buyers evaluating glass beads for a specific project should start from the governing standard, then select the refractive index and gradation that meet the retroreflectivity requirement. Supplier evaluation should include production capacity, laboratory testing, certification and the ability to supply the relevant standard grades consistently.

Dylan Technology provides a road marking glass bead range that covers AASHTO M247 Types 1–4, EN 1423, EN 1424, BS 6088A/B and AS/NZS Types B, C and D, with RI 1.6 and RI 1.7 options for higher retroreflectivity applications. The company combines a 100,000-ton annual production capacity with in-house particle size, reflectivity and wear resistance testing, and supports OEM requirements with a 1-ton MOQ and 45–60 day lead time.