Operations
14
M E A S U R I N G V I S C O S I T Y
Prior to operations, check the viscosity or thickness of
the lacquer to be used. To measure the viscosity of
the lacquer, you will need a #2-Zahn Viscosity Cup
and a stopwatch. The cup has a hole in the bottom
from which the lacquer will run out until the cup is
empty.
The amount of time that it takes to empty the cup
(Zahn-seconds) is used to calculate the viscosity or
thickness of the fluid tested. The thicker the fluid, the
longer it will take to empty the cup.
NOTE: Water measures at a rate of 14 Zahn-
seconds.
The lacquer being used for coating should drain in the
35 to 50 Zahn-second range.
To measure the viscosity of the lacquer you are using
in your laminator, you will need the following:
1. One 16-ounce cup of lacquer. (If necessary, filter
the lacquer to ensure that there are no particles
present which may otherwise block the drain hole
in the Zahn Cup.)
2. A #2 Zahn Viscosity Cup
3. A stopwatch
Figure 17: #2 Zahn Viscosity Cup
MEASUREMENT PROCEDURE
1. Immerse the #2 Zahn Cup fully in the lacquer.
2. Raise the cup out of the lacquer. Immediately as
the top edge of the #2 Zahn Cup emerges from
the lacquer, start the stopwatch.
3. The stream of lacquer draining from the hole in
the bottom of the #2 Zahn Cup will get thinner
and thinner as the cup empties, until a point
where the continuous flow is broken.
4. Watch for the break in flow about 10 in. (25 cm)
below the bottom of the cup.
5. When the stream breaks its continuous flow, stop
the stopwatch.
NOTE: Flow will most likely resume again
following the initial break in continuous
flow. Ignore any additional flow.
6. Repeat the measurement a second time to verify
the accuracy of the measurement. Values from
both measurements should be identical.
7. If the lacquer is in the 35-50 Zahn second range, it
is good to use. Thick lacquer can be restored to
normal by adding distilled water.
NOTE: Particles in the lacquer may plug the hole
in the cup, breaking the stream giving
you an inaccurate time. Verify that no
particles have plugged the hole.
