Durability Marking shall be easily legible, durable and indelible.
Laser marking directly on the product and marking made by moulding,
pressing or engraving are not subjected to this test.
Compliance is checked by inspection, using normal or corrected
vision, without additional magnification and, if necessary, by the
following test.
The test is done by rubbing the marking for 15 s with a piece of
cotton cloth soaked with water and again for 15 s with a piece of
cotton cloth soaked with n-hexane 95 % (Chemical Abstracts Service
Registry Number, CAS RN, 110-54-3).
NOTE n-hexane 95 % (Chemical Abstracts Service Registry Number, CAS
RN, 110-54-3) is available from a variety of chemical suppliers as
a high pressure liquid chromatography (HPLC) solvent.
When using the liquid specified for the test, precautions as stated
in the relative material safety datasheet provided by the chemical
supplier shall be taken to safeguard the laboratory technicians.
The marking surface to be tested shall be dried after the test with
water.
Rubbing shall commence immediately after soaking the piece of
cotton, applying a compression force of (5 ± 1) N at a rate of
about one cycle per second (a cycle comprising a forward and
backward movement along the length of the marking). For markings
longer than 20 mm, rubbing can be limited to a part of the marking,
over a path of at least 20 mm length.
The compression force is applied by means of a test piston which is
wrapped with cotton comprising cotton wool covered by a piece of
cotton medical gauze.
The test piston shall have the dimensions specified in Figure 5 and
shall be made of an elastic material which is inert against the
test liquids and has a Shore-A hardness of 47 ± 5 (for example
synthetic rubber).
Figure 5 – Test piston dimensions
When it is not possible to carry out the test on the specimens due
to the shape/size of the product or the marking is not accessible
with the test piston:
– a suitable piece having the same characteristics as the product
can be submitted to the test
or
– another test piston with different shape can be used on the
condition that radius B is kept.
