ALTANA Balanced Beam - Manual (Page 7)

6
Operation
Operation
Level the base plate using the bubble level and the
three adjustable feet. Secure the desired stylus in
position in the appropriate end of the holding rod.
The Loop Stylus fits into the end of the rod with
the two-hole stylus clamp. The Needle Stylus can
be placed in either of the two holes, as can the
Rod, Spit and Ball-tipped styluses. The Hoffman
Tool is mounted in the single-hole end of the
rod. Styluses are held secure at either end by
tightening a screw. Turn the instrument so that the
stylus end is toward the operator and the counter-
weight is pointing away. The sample platform
may then be pulled or pushed freely using both
handles.
The test specimen for this instrument must
be flat and smooth. When a coating is tested,
its substrate must have this form. The sample
platform measures 4-3/4“ x 8“ (12.1 cm x 20.3
em). The sample can be as wide as 5“; although
it can be somewhat longer than the bed, the the
Needle Stylus onto the sample and then with a
uniform motion pull the sample and inch or two
using a very light initial load (about 50 gm) on the
weight holder. Make successive passes across
the sample, increasing the load by a convenient
increment (perhaps as little as 10 gm) until the
needle cuts through the film to the substrate. The
coating should be penetrated with less than 1 kg.
A load of 1.5 kg or more may damage the Needle
Stylus. Where relatively heavy loads are needed
for scratch testing, the sturdier Hoffman Tool or
Rod Stylus can be used in the same manner.
Low power magnification may be required for
determining whether the Needle Stylus exposed
the substrate, especially when the coating is
transparent or the same color as the substrate.