ALTANA Balanced Beam - Manual (Page 8)

7
The uncoated surface of any rigid material may be
tested for hardness by finding the load required to
make a visible scratch on the surface. The Needle
Stylus, Hoffman Tool or Rod Stylus are used for
this purpose.
The two Ball-Tipped styluses may not actually
scrape or scratch, but will depress a coating or
other material under sufficient load, creating a
groove in the surface. As with scratch resistance,
resistance to „grooving“ is a practical test because
the product may be subjected to forceful contact
with sharp and blunt objects.
The resistance of a surface to penetration by
too sharp and too blunt objects mayor may not
correlate.
The Spit Stylus is used for rubbing tests. A soft
object supplied by the user is impaled upon the
stylus and then rubbed against the test surface
under a certain load. Examples are rubbing an
eraser against printed characters on paper or a
piece of shoe leather against a polished floor tile.
Operation