Nickel Release Testing Protocol (EN 1811, EN 16128 & EN 12472)

1. Where does the nickel limit come from, and which method produces the figure?

The obligation comes from Regulation (EC) 1907/2006, Annex XVII, entry 27: an article in direct and prolonged contact with the skin must release less than 0.5 µg of nickel per cm² per week, and less than 0.2 µg/cm²/week for post assemblies inserted into pierced ears. That is the whole legal requirement. Everything else is about which method produces the figure you compare against it, and getting that wrong is the most expensive mistake in this file.

EN 1811 excludes eyewear from its own scope. A report on a spectacle frame citing EN 1811 rather than EN 16128 names a method whose scope does not cover the article, and that is a documentary defect regardless of the number it carries.

2. When can you not use the EN 12472 ageing step?

EN 12472:2020 accelerates wear and corrosion to approximate about two years of normal use before the release test is run. Two exclusions in its own scope decide whether you can use it at all:

• articles whose outer coating itself contains nickel, and
• articles inserted into pierced ears or other pierced body parts.

A piercing post is therefore tested to EN 1811 directly, against the stricter 0.2 µg/cm²/week threshold, with no ageing step. Sending one through EN 12472 first produces a result the standard does not authorise.

Practical consequence for ordering: ageing consumes a second set of specimens and a second volume of sweat. Budget both, or the campaign stops halfway.

3. What is in EN 1811 artificial sweat, and why does its nickel background matter?

EN 1811 artificial sweat is a deliberately simple aqueous solution, adjusted to pH 6.5:

• Sodium chloride, 0.5 % (5 g/L)
• Urea, 0.1 % (1 g/L)
• Lactic acid, 0.1 % (1 g/L)

There is no histidine and no phosphate. Those belong to the ISO 105-E04 perspiration family, which answers a colour-fastness question, not a metal-release one. If a supplier ships you a histidine-bearing solution for EN 1811, it is the wrong fluid.

The acceptance limit is 0.5 µg/cm²/week. A solution carrying its own nickel background eats part of that budget before the article contributes anything, and the smaller the article, the larger the share. This is why the certified low-nickel background on the Certificate of Analysis is the field to check first, ahead of the pH: a pH out of tolerance changes the release rate, but a contaminated blank can invent a failure outright.

4. How much solution does an EN 1811 immersion need?

The volume is set by the exposed surface area, not by the number of articles: 1 mL of solution per 1 cm² of exposed surface. Ten rings of 8 cm² is 80 mL; the same ten rings in duplicate is 160 mL. The specimen is held in a sealed vessel at 30 °C for one week (168 h), in the dark and without agitation.

If the surface area has not been measured yet, the volume planner in our tools section takes a count and a per-article figure and returns the litres, including the spare a campaign actually consumes.

5. How do you read and report a nickel release result?

The solution is analysed by ICP-MS or FAAS against certified nickel standards, and the result is expressed as µg/cm²/week. Two things belong in the report beside that figure: the measured surface area, because the result is normalised to it, and the blank, because it is subtracted from it.

A result close to the limit is a result about your measurement as much as about your article. Laboratories handle that with a decision rule agreed in advance rather than by comparing a bare mean to 0.5, and the surface-area measurement is usually the larger contributor to the uncertainty, not the ICP-MS.

This guide describes the decisions and the sequence. It does not reproduce the text of EN 1811, EN 16128 or EN 12472, which you need to obtain from CEN or your national body, and it does not replace your laboratory's own validated method.