Prevention of nickel release from decorative nickel-chromium electroplated articles in the context of allergic contact dermatitis

Figures & data

1. Bright nickel-chromium plated ABS plastics specimen

Table 1. Rate of nickel release from specimens A to G in triplicate

Specimen	Protective coating	Minimum thickness of chromium/μm	Top-coat	Trial	Nickel release rate / μg/cm^2/week	Pass/fail^*
A	Regular Hexavalent Chromium (Cr^6+)	0.16	—	1	< 0.01	Pass
				2	< 0.01
				3	< 0.01
B	Regular Hexavalent Chromium (Cr^6+)	0.27	Electrophoretic	1	< 0.01	Pass
				2	0.01
				3	0.01
C	Regular Hexavalent Chromium (Cr^6+)	0.18	Sol-gel	1	0.01	Pass
				2	< 0.01
				3	< 0.01
D	Microporous Hexavalent Chromium (Cr^6+)	0.40	—	1	0.13	Pass
				2	0.01
				3	0.23
E	Microporous Hexavalent Chromium (Cr^6+)	0.28	Electrophoretic	1	< 0.01	Pass
				2	0.01
				3	0.01
F	Microporous Hexavalent Chromium (Cr^6+)	0.16	Sol-gel	1	< 0.01	Pass
				2	0.07
				3	< 0.01
G	Regular Trivalent Chromium (Cr^3+)	0.41	—	1	2.82	Fail
				2	4.19
				3	1.74

* Note: Deemed to pass if the nickel release rate is < 0.5 μg/cm²/week.

2. Reverse side of specimen, with blue masking paint applied before testing for nickel release

3. Reverse side of specimen (non-significant surface), showing yellow colour of exposed nickel at the racking point

Table 2. Test method verification. Nickel release from reverse (non-significant) surface where nickel was exposed at racking points

				Non-significant surface covered with paint		Non-significant surface exposed
Specimen	Protective coating	Top-coat	Trial	Nickel release rate / μg/cm^2/week	Pass/fail	Nickel release rate / μg/cm^2/week	Pass/fail
D	Microporous Hexavalent Chromium (Cr^6+)	—	1	0.13	Pass	9.94	Fail
			2	0.01		6.35
			3	0.23		4.70
E	Microporous Hexavalent Chromium (Cr^6+)	Electrophoretic	1	< 0.01	Pass	0.24	Pass
			2	0.01		0.03
			3	0.01		0.09
F	Microporous Hexavalent Chromium (Cr^6+)	Sol-gel	1	< 0.01	Pass	0.62	^*Please see NOTE
			2	0.07		0.61
			3	< 0.01		0.82

* Note: “EN 1811:2011, Annex.‘Expanded measurement uncertainty of the test procedure and compliance assessment’. For the migration limit of 0.5 μg/cm²/week, nickel release of ≤ 0.28 μg/cm²/week is compliant. For values >0.28 to < 0.88 μg/cm²/week, no clear decision is possible.