If you sell road marking beads long enough, you learn to read a spec sheet the way a translator reads two languages. AASHTO M247 and EN 1423 are both trying to describe the same thing, a pile of tiny glass spheres that bounce headlights back at drivers, but they say it in different numbers.
The short version
AASHTO M247 is the US standard, published by the American Association of State Highway and Transportation Officials. EN 1423 is the European standard for drop-on beads, part of a family that also includes EN 1424 for premix. A contractor in Texas will likely see M247 in the tender, a contractor in Germany will see EN 1423, and a contractor exporting somewhere in between has to deal with both.
How the numbers line up
M247 Type 1 is the common drop-on grade for paint, with a sieve range that runs from about 1180 to 150 micrometers. EN 1423 drop-on beads land in a similar window, around 850 down to 125 micrometers, with tight passing percentages at each sieve. The chemistry is close too: both call for soda-lime glass with a refractive index around 1.5, and roundness of at least 70 to 80 percent depending on the type.
Where they stop lining up is in the details. The sieve distributions differ, and a bead that passes M247 Type 1 might miss an EN 1423 band because a bit too much material sits in a size range the European spec allows only a few percent of. This is the trap we warn exporters about: do not assume one compliant batch automatically clears the other standard. We keep sieve data for both, and when a customer changes target market we re-screen and re-test rather than ship from memory.
What else hides in the spec
Beyond particle size, both standards poke at things like moisture resistance and, in some versions, how the beads behave after being coated. Some buyers read the refractive index requirement and stop there, but the reflectivity test matters more in practice. A bead can meet the RI number on paper and still give a mediocre line if its roundness is poor, because light bounces off a lopsided bead at the wrong angle. We tell customers to look at the whole page of the spec, not just the headline number.
Road marking bead standards: the full matrix
AASHTO M247 and EN 1423 are the two names that come up most often, but they are not the only standards a road marking bead may be judged against. Depending on where the project sits, the tender may name BS 6088, AS/NZS 2009, JIS R3301 or GB/T 16311 instead. The table below puts the main standards side by side so you can see which one applies to your market before you quote.
| Standard | Region / market | Type or class | Typical sieve range | Common application |
|---|---|---|---|---|
| AASHTO M247 | United States | Type 1 | 1180–150 µm | Drop-on beads for paint and thermoplastic |
| AASHTO M247 | United States | Type 2 | 850–300 µm | Premix beads, thicker markings |
| EN 1423 | European Union | Drop-on | 850–125 µm | Surface-applied beads for markings |
| EN 1424 | European Union | Premix | 600–125 µm | Beads mixed into the marking material |
| BS 6088 | United Kingdom | Class A | 850–300 µm | General road marking beads |
| BS 6088 | United Kingdom | Class B | 600–300 µm | Finer finish, urban markings |
| AS/NZS 2009 | Australia / New Zealand | Type B, C | 850–180 µm | Highway markings, high rainfall zones |
| JIS R3301 | Japan | — | 850–180 µm | Road marking and industrial use |
| GB/T 16311 | China | 2024 revision | Per grade | Domestic marking, revised requirements |
Two things stand out when the standards are lined up this way. First, the sieve windows overlap heavily — most road marking beads across all these markets sit between roughly 1.18 mm and 125 µm. Second, the boundaries are not identical, which is exactly why a batch that passes one standard does not automatically clear another.
What actually differs between the standards
The headline sieve range is only part of the document. Each standard also specifies passing percentages at each individual sieve, and those percentages are where most compliance failures happen. A batch can sit inside the overall window and still fail because too much material collected on a single intermediate screen.
Beyond grading, the standards touch on:
- Refractive index — most call for soda-lime glass at RI 1.5, with higher-index grades specified separately where wet-night performance is required.
- Roundness — commonly a minimum of 70–80 percent, though the measurement method varies between standards.
- Moisture resistance — relevant for coated beads and for shipments that spend weeks in transit or in port.
- Coating requirements — whether the bead is sold bare or with a moisture-proof or adhesion coating, and how that coating is tested.
- Reflectivity test — the practical performance check, and arguably more meaningful than the RI figure alone.
The reflectivity test deserves its own note. Some buyers read the refractive index requirement, confirm the number, and stop there. But a bead can meet the RI figure on paper and still produce a mediocre line if roundness is poor, because a lopsided bead sends light off at the wrong angle rather than back toward the driver. Reading the whole spec page, not just the headline number, is what separates a compliant shipment from a good one.
Choosing the right standard for your project
In practice the choice is rarely yours to make — the tender or the client’s specification names the standard, and the beads are tested against it at the site gate. But when you are quoting into a market for the first time, or when a project spans more than one region, it helps to know where the differences sit.
| If your project… | Then specify | Watch out for |
|---|---|---|
| Is tendered in the United States | AASHTO M247, Type 1 or 2 | Type 2 is for premix — do not substitute |
| Is tendered in the EU | EN 1423 (drop-on) or EN 1424 (premix) | Passing percentages at each sieve |
| Is tendered in the UK | BS 6088 Class A or B | Class B is a narrower band |
| Is tendered in Australia or NZ | AS/NZS 2009 | Wet-night performance requirements |
| Spans two regions | Both standards, verified | Do not assume one clears the other |
| Is in China | GB/T 16311 (2024 revision) | Recent revision changed requirements |
Why a batch can pass one standard and fail another
This is the single most common surprise for exporters, so it is worth spelling out. Say a batch has a sieve distribution of 2 percent oversize, 15 percent on the coarse screen, 60 percent in the middle band and 23 percent on the fine screen. That distribution might sit comfortably inside AASHTO M247 Type 1, and still fail EN 1423 because the European standard caps the material on one of the intermediate screens at a lower percentage.
The chemistry is rarely the problem — both standards ask for essentially the same soda-lime base. The roundness figure is usually met too. It is the size distribution, measured screen by screen, that decides whether a batch clears both. When a customer changes target market, the safe move is to re-screen and re-test rather than ship from memory or from an earlier certificate.
What to ask your supplier for
Whatever standard your project names, the document that matters at the gate is the sieve analysis report for the actual lot. Not a generic certificate, not a specification from an earlier order — the report for the bags on the truck. Ask for it before the shipment leaves, so any discrepancy is a factory conversation rather than a rejected delivery.
A supplier who can produce sieve data for more than one standard is worth keeping. It means that when your next project moves to a different market, the batch can be verified against the new specification without starting the qualification process from scratch.
If you are between two markets
Tell us which standard your current project names. If the answer is both — which happens with some international jobs — we will confirm the batch passes both before it leaves the factory, not after it arrives at the port.
Why this matters to a buyer, not just a lab
Spec compliance is not paperwork for its own sake. On a motorway tender, the beads are tested against the named standard, and a batch that fails means the whole lot gets rejected at the site gate. That is a costly surprise nobody budgets for. When we quote, we state which standard the batch is produced to, and we can include the sieve report with the shipment so the contractor has the numbers in hand before the inspector asks.
If you are between two markets
Tell us which standard your current project names. If the answer is both, which happens with some international jobs, we will confirm the batch passes both before it leaves the factory, not after it arrives at the port.
Frequently asked questions
What is the difference between AASHTO M247 and EN 1423?
AASHTO M247 is the US standard published by the American Association of State Highway and Transportation Officials; EN 1423 is the European standard for drop-on beads. Both specify soda-lime glass at roughly RI 1.5 with roundness of 70–80 percent, and their sieve windows overlap heavily. The difference sits in the passing percentages at each individual sieve, which is why a batch that passes one standard may not automatically clear the other.
Can a batch of glass beads pass AASHTO M247 and fail EN 1423?
Yes, and this is the most common surprise for exporters. A batch can sit comfortably inside the overall sieve window of AASHTO M247 Type 1 and still fail EN 1423 because the European standard caps the material retained on an intermediate screen at a lower percentage. The chemistry and roundness are rarely the issue — it is the screen-by-screen size distribution. Always re-screen and re-test when changing target market.
What is the refractive index required for road marking glass beads?
Most road marking standards call for soda-lime glass at a refractive index of approximately 1.5. Higher-index grades (RI 1.7 and above) are specified separately for applications needing better wet-night visibility, such as high-speed roads, tunnels and airport surfaces — and they cost more.
Which standard applies to road marking beads in the UK?
BS 6088, which defines Class A and Class B. Class A beads typically sit in the 850–300 micron range for general road marking; Class B is a narrower band used for finer urban markings. A UK project will normally name BS 6088 in the tender rather than AASHTO or EN.
What documents should I request with a glass bead shipment?
Ask for the sieve analysis report for the actual lot — not a generic certificate and not a specification from an earlier order. That report is what the inspector tests against at the site gate. Requesting it before the shipment leaves the factory turns a potential rejected delivery into a factory conversation.
Related reading
- Standards (short) — bead standards
- GB/T 16311-2024 — bead standards
- Spec Checklist — road marking selection
- Why Beads Fail — road marking selection