Choosing a bulb to charge your glow in the dark
The brightness and type of bulb
determines the efficiency at which
phosphorescent material charges.
Efficient bulbs not only charge
faster, but can obtain a brighter
level of glow.
A black light shining on a glow
surface for 30 seconds will cause
that surface to be 10 times brighter
than a flashlight on it for 6 hours.
Here is a simple list of bulbs in
order from least to most efficient:
Incandescent - standard light bulb
Compact Fluorescent or CFL - spiral
Fluorescent Bulbs - long tubes
Black Light Tube
The efficiency of light as a
phosphorescent charging source is
determined by its brightness and its
spectrum. White light is comprised
of equal amounts of all of the
colors, such as red, green, and
blue. White light bulbs typically
also emit ultraviolet (UV) light,
which is the "color" above purple in
the spectrum, which humans can not
Each part of the spectrum effects
glow in the dark materials
Red light actually discharges the
Green light is neutral.
Blue Light inefficiently charges the
Ultraviolet light charges the
A standard incandescent light bulb
emits similar amounts of the four
colors above. The green does not
effect the glow pigments. The red
discharges and the blue charges in
similar amounts, which results in a
cancelation. The result is that only
the ultraviolet is working to charge
the phosphorescent pigments.
Therefore, when using a 100 watt
incandescent light bulb as a
charging source, only about 10-25
watts are working to actually charge
the pigment. Therefore, a 60 watt
black light bulb will far outperform
the higher powered white light.
The efficiency of white light can be
determined by the ratios of the
colors contained. "Warm" lights
contain more red and therefore are
poor for charging glow in the dark
items. "Cool" or "Daylight" bulbs
contain more blue and therefore are
slightly more efficient. Fluorescent
bulbs, both CFL and tube style,
naturally emit more ultraviolet
light, which makes them more
Black lights have another major
advantage. White light bulbs cause
the human eye to adjust to the
bright light. When the light is
removed, it takes 15 minutes for
human eyes to adjust back to the
darkness. If your eyes are adjusted
for a bright room, then even the
brightest phosphorescent material
will appear dim when the light is
Black lights do not cause your eyes
to readjust. For most applications,
this will cause the glow in the dark
materials to "appear" considerably
The final major consideration is direct vs. reflected light.
Many ceiling fixtures are designed to point light down onto a room.
Therefore, the only light reaching the glow in the dark stars on your
ceiling is reflected. Reflected light is extremely inefficient for
This holds true for sunlight entering through a window. While a
room inside may look bright, it is mostly from reflected light.
This is also why glow in the dark house numbers on a west-facing house
are brighter at 10pm than an east-facing house.
A frequently asked question at Glow Inc. is "How long does it take to
get a full charge" The easy answer is that any of our products will be
at their maximum charge from any light source in 20 minutes. However,
that is a useless answer.
"Maximum Charge" will change depending on the light source. A black
light on for seconds can cause our products to glow brighter than an
incandescent bulb lit for 10 hours. Of course, the speed of charge is
also determined by the light source.
A "full charge" is also a hard statement. Under black light, most
pigments will get to 80% of their charge within seconds, 90% over 30
seconds, 95% over about 2 minutes, 100% in about 10 minutes.
This is further complicated by the size of the pigment. Larger pigments
can glow brighter and longer, but charge slower.
In conclusion, use a black light if possible. If white light is
needed use CFL "Daylight" bulbs.A request from the author:
Glow Inc. has always
been at the forefront of providing free technical information on the
subject of "glow in the dark". Most recently, we added the
Glow in the Dark Forum so that
customers can add to this free information base.
However, we are in
desperate need of exposure on the Internet. If you enjoyed this
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