Chapter: Mark specimens
52 M16-16905-EN
• applying the marks to the specimen so that they stay in place and are visible to the
camera throughout the test
If you are testing to a particular standard, gauge length and gauge width are often pre-
defined and you must apply marks as specified in the standard.
Marking tips
• Test your specimens as soon as possible after applying the marks to minimize the
possible effects of solvent from inks or adhesive on the specimen properties
• If your specimen breaks at the point where the mark is applied, consider an
alternative marking method
• If your specimen undergoes long extension during testing, make sure that the marks
are still visible at the end of the test
Dots must be used if you are measuring both axial and transverse strain. Lines can be
used for axial measurement only.
Applying ink dots
The minimum recommended diameter for ink dots is 2mm. The maximum
recommended diameter is 4mm.
The marking jigs provided are designed to be used with the marking pens
provided.These pens have spring-loaded tips that prevent too much pressure being
applied which would accelerate damage to the tip. Each jig has several sets of holes
arranged to produce 3mm diameter dots at commonly-used axial gauge lengths and
transverse gauge widths.
1. Ensure that the marking jig is clean and has no residue of a previous ink color that
could cause cross-contamination and reduce contrast between the dot and the
specimen.
If you are continuously swapping between black and white ink, it is recommended
that you purchase an additional marking jig.
2. Locate the holes in the jig that match your chosen gauge length.
3. Select the appropriate ink color.
4. Make sure the specimen is clean and free from grease.
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