Can You Identify RoHS-Compliant Fasteners by Colour?
The ten restricted substances, and how to judge compliance by surface finish.
A fastener falls under RoHS not because of its base material but because of its surface finish (plating). Cheap, corrosion-resistant hexavalent chromium (Cr⁶⁺) was traditionally in wide use.
The ten restricted substances
| Group | Substances |
|---|---|
| Heavy metals (4) | Lead (Pb), mercury (Hg), cadmium (Cd), hexavalent chromium (Cr⁶⁺) |
| Flame retardants (2) | PBB, PBDE |
| Plasticisers (4) | DEHP, BBP, DBP, DIBP |
The four plasticisers were added by the RoHS 2 amendment (EU 2015/863, commonly "RoHS 3") and applied in full from July 2019
Can you tell by colour? Only partly
The short answer is that you must judge by the finish material and its composition, not by colour. There are useful tendencies, however.
| Finish | Appearance | RoHS |
|---|---|---|
| Yellow zinc plating | Yellow, iridescent | ❌ Usually hexavalent |
| Hexavalent clear / black chromate | Silver-white / black | ❌ Hexavalent |
| Trivalent clear / black chromate | Silver-white / black | ✅ Compliant |
| Nickel plating | Uniform silver | ✅ Compliant |
| Dacromet (original formulation) | Silver-grey | ❌ Contains hexavalent chromium |
| Geomet and other chromium-free zinc flake coatings | Silver-grey | ✅ Compliant |
| Pickling (stainless) | Matte silver | ✅ No plating involved |
Note that the table contains two pairs that look identical but are judged oppositely. Clear and black chromate exist in both hexavalent and trivalent form and cannot realistically be told apart by eye, and Dacromet and Geomet are both silver-grey. These are the clearest demonstration that colour is not a criterion. "Dacromet" is often used loosely on site as a generic term for zinc flake coatings, so check the exact process name on the specification and which chromate (hexavalent or trivalent) it uses.
More recently, trivalent yellow chromate has appeared as a replacement for hexavalent yellow, so a yellow part may well be compliant. Whatever the colour, appearance is only an indication — confirm from the process specification and compositional analysis.
Many people believe yellow zinc means "no plating applied". It does not. It is a yellow chromate conversion coating, and it normally uses hexavalent chromium. If your customer requires RoHS compliance, avoid yellow zinc plating.
There is no such thing as a "RoHS certificate"
RoHS is not a third-party certification scheme; it is a manufacturer's self-declaration. What actually answers a request to "send us your RoHS certificate" is a material test report from an accredited laboratory.
A fastener made only of metal and plating cannot contain the flame retardants (PBB, PBDE) or the four phthalate plasticisers, which are organic compounds. The substances that genuinely need checking narrow to the four heavy metals (Pb, Hg, Cd, Cr⁶⁺). Parts with polymer elements — nylon patch locking screws, SEMS assemblies with resin washers — do need those elements checked separately.
When a customer asks for RoHS evidence, we provide a test report from an accredited external laboratory covering the four heavy metals. We also support changing the specification to a RoHS-compliant finish. Tell us your customer's requirements and we will propose a suitable finish.
※ Nickel plating is not restricted under RoHS. However, products sold in Europe that stay in prolonged contact with skin may be subject to the separate REACH restriction on nickel release, which should be checked.