1. Sprinkle some powder across the plate.
2. Starting at a signal of a few hundred hertz, slowly
turn the amplifier power up until the powder starts
to vibrate. Adjust the frequency and volume until
To reduce friction, I periodically rub graphite powder over the plate and brush off any excess. Then
my other powder slides around on this slick surface
like a cat in roller skates.
Clean patterns will appear for only those frequencies that resonate with the plate. On smaller plates
only very high frequencies will show a stable pattern of nodes and antinodes; on larger plates, lower
frequencies will resonate as well. On a large plate
with a high frequency, you’ll see a detailed pattern
across the plate.
On a round plate, you’ll mostly get concentric
circles, with the number of circles indicating the
ratio of the driver frequency to the plate’s natural
fundamental frequency. In such cases, the driver
is playing a harmonic (or multiple) of the lowest
frequency that the plate produces naturally when
you strike it. With some frequencies, you’ll see a
serpentine pattern on the round plate.
On a square plate, or a plate in the shape of a
violin or other complex shape, the resonances are
more complex and interesting.
If you want a permanent display of your vibrational patterns, photography is the way to go.
Although if you have an extremely effective filter
mask and a high tolerance for a horrible mess,
I would think that laser printer toner would make a
nice pattern, and then, using a heat gun from below,
you could fuse it to the metal for a permanent
display. I haven’t tried this, however. Also note that
laser toner is extremely bad for your lungs, laundry,
and household harmony.
KEEP YOUR POWDER DRY
Any fine powder will work, but the finer the powder,
the more sensitive it will be to vibrations, enabling
it to work at lower volumes. If you’re using a coarse
powder, you may need to turn up the volume quite
a bit before it bounces into place.
If the powder is sticky or overly fine, it may not want
to bounce at all, but instead may stick to the plate and
ignore even the most abusive volume levels.
Some powders, such as salt or sugar, will absorb
moisture from the air and melt (especially here in
Texas), making a terrible mess. Gelatin and graphite
powder are both very fine, but tend to stick to the
plate over time. Fine white sand should work nicely,
with minimal mess.
The traditional superfine substance of choice is
Lycopodium powder, which is the spore of a particular fern. This powder is used by magicians and
pyrotechnicians as a flash powder, and it can be
found at chemical supply houses.
See Edwin Wise’s Chladni plate in action at