Road-marking glass beads are sold by standard as much as by diameter. Buyers in the US, Europe and the UK quote three main documents, and knowing which one your destination expects saves a lot of back-and-forth.
AASHTO M247 (United States)
AASHTO M247 covers glass beads for pavement markings, dividing them into types based on particle-size distribution (often used as Type I / II / III in tenders). It focuses on roundness, cleanliness and grading. If you supply state DOT or airport projects in the US, expect M247 to be named in the spec.
Cross-reference: the same bead under different names
Buyers moving between markets regularly hit the problem of comparing quotations that use different terminology for essentially the same product. The table below maps the commonly used gradations across the main standards so you can normalise a set of quotations onto one axis before comparing price.
| Typical use | Mesh range | Micron range | AASHTO M247 | EN 1423 / 1424 | BS 6088 |
|---|---|---|---|---|---|
| Drop-on for thick markings | 20–40 | 850–425 | Type 3 / Type 4 | Coarse gradation | Type A |
| General drop-on | 40–80 | 425–180 | Type 2 | Standard gradation | Type A / Type B |
| Premix / intermix | 60–140 | 250–106 | Type 1 | EN 1424 grading | Type B |
| Thin film and high-speed markings | 100–200 | 150–74 | Type 1 fine | Fine gradation | Type B fine |
| Specialty and decorative | 170–325 | 90–44 | Not typically specified | Project-specific | Not typically specified |
Read this table as a translation aid, not a certification. Equivalence between standards is approximate, and a specifier who has written AASHTO M247 Type 2 into the contract is entitled to that certificate, not to an argument that some other grade is “basically the same”.
EN 1423 / EN 1424 (Europe)
EN 1423 governs drop-on beads applied to road markings; EN 1424 covers premix beads. European buyers – especially in Germany, the UK and Scandinavia – increasingly require EN 1423 certification and third-party test evidence as a condition of supply.
BS 6088 (United Kingdom)
BS 6088 splits road-marking glass beads into grades (A and B) with defined size bands and roundness levels. It is still widely referenced in UK specifications alongside the newer EN documents.
Other markets at a glance
- Japan: JIS R 3301 | Korea: KS L 2521
- Australia / NZ: AS/NZS 2009 | Brazil: ABNT NBR 6831 / NBR 16184
- China: GB/T 24722
Refractive index classes and why the number is quoted separately
Every one of these standards controls refractive index as a separate parameter from gradation, because RI determines how much light comes back to the driver rather than how much light enters the bead. A bead that is correctly graded but has the wrong RI will meet the sieve analysis and fail the field performance test.
| RI class | Typical value | Primary use | Notes |
|---|---|---|---|
| Standard soda-lime | 1.50–1.52 | Dry-night visibility, general road marking | The default grade; widest availability and lowest cost |
| Intermediate | 1.55–1.60 | Improved wet-night performance where budgets are constrained | Less common; availability varies by region |
| High index | 1.70 and above | Wet-night and rain-night visibility, high-speed roads | Higher cost; usually specified only on critical routes |
Standard beads at RI 1.5 rely on the air gap between the bead surface and the water film for retroreflection. Once the marking is under a continuous water film that air gap is lost and retroreflectivity drops sharply, which is the physical reason high-index beads exist at all.
Practical tip for buyers
Ask for the exact type/grade plus the size range before ordering – two tenders that both say “M247” can need different mesh cuts. A reliable supplier will confirm grading on the batch and give test reports.
Linghang manufactures drop-on and premix road-marking beads in mesh 20-100 with R.I. 1.5 and roundness ≥80%, and can align grading with M247, EN 1423/1424, BS 6088 and GB/T 24722 expectations. Contact us with your project standard and target country for a quote.
For a fuller technical treatment of Bead standards, see our guide: AASHTO M247 vs EN 1423 vs BS 6088: Road Marking Bead Standards Compared.
Purchasing checklist for cross-border specification
When you buy from a supplier outside your own market, the standard on the certificate and the standard in your contract are two different things. Close the gap explicitly in the purchase order.
| Item | What to require | Failure mode if omitted |
|---|---|---|
| Standard named in full | Standard number, year and type or class | Supplier ships a different type that meets the same standard |
| Gradation data | Batch sieve analysis, not a catalogue sheet | Nominal gradation may sit at the tolerance edge |
| RI certificate | Test report with method and value | Only roundness and grading are verified |
| Roundness | Percentage plus test method | Angular and broken beads pass as “beads” |
| Coating type and coverage | Coating named, coverage stated | Adhesion to the marking material varies batch to batch |
| Packaging and marking | Net weight, batch number, production date on each bag | Traceability lost if a batch fails in the field |
| Third-party test report | Independent lab, report referencing the batch | Self-declared data cannot be challenged |
If you are tendering across more than one market and need the same product certified to two different standards from one production batch, send us the two specifications and we will confirm which gradation satisfies both before you commit.
Related reading
- GB/T 16311-2024 — bead standards
- Drop-On vs Premix (short) — road marking selection
- Spec Checklist — road marking selection