There are two types of UV emission on BL(B) bulbs: Actinic and pure black
light.
My experience:
BLB has peak around 360 nm and dark violet-blue glass.
BL has peak around 360 nm and untinted glass.
Actinics have something different, such as wider bandwidth or longer
peak wavelength. One example is the 03 actinic, which has peak around
410 nm or maybe a few nm longer.
"Actinic" refers to taking some of the lower wavelengths, like the
254/313/356 clusters and converting them using a fluorescent powder to a
continuum, with a peak either at ~370-375 or ~380-390, depending on type.
I thought the longwave mercury line cluster was 365-366 nm and it is not
utilized well (often not at all) by most fluorescent lamp phosphors. One
blue-glowing phosphor used in at least some triphosphors and Philips
"Special Blue" does have significant utilization of 365-366 nm.
Phosphor utilization of 365-366 and 313 only matters a little, since low
pressure mercury does not produce a whole lot of 365-366 or 313 but mainly
254 with 185 in a somewhat distant second place.
It is true that acrylic blocks the 356 line, but it doesn't block the
actinic continuum which peaks at 370/390, so your fluorescence might come
from this area.
Acrylics vary. But in my experience the usual stuff mostly blocks 360
and 365-366. The phosphor peak in BL and BLB is at a wavelength slightly
shorter than that of the 365-366 nm mercury line cluster, which is far
weaker than the phosphor output. The phosphor output is strong at least
from the low 350's to about 370, maybe a little wider. I have seen
somewhat wider in at least some Sylvania and Moolim lamps.
To summarize:
TLAK (BL): Actinic fluorescent with peaks at 370/390nm
If it really peaks that long, then it's different from the BL lamps that
I see in the USA, which peak around 360 nm.
BLB: Black light fluorescent: Actinic + Wood's glass, peaks at 370/390 and
filters out visible
USA BLB lamps peak around 360. But even here BLB is made with Wood's
glass and BL is made with untinted glass.
In my experience in the USA fluorescent lamps referred to as "actinic"
have untinted glass and a phosphor that differs from that of BL by peaking
at a longer wavelength such as 410 or low 410's nm or by having a wider
bandwidth that extends significantly into the visible violet.
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Another one: The 350BL. This is an untinted blacklight fluorescent
lamp with a peak wavelength of 350 nm. This is supposedly more attractive
to insects than other blacklights with a peak wavelength of 360 nm, so
350BL is used in bugzappers.
It appears to me that the advantage of 350BL is its wider bandwidth. I
have made a homebrew bugzapper and tried a few different fluorescent lamps
in it, and my best results were with plain blue ("B"). As a result, I
suspect insects find more attractive lamps that not only have peak
wavelength in the blue-UV range but also wider bandwidth - possibly
with spectrum not too different from that of clear blue sky. Also I found
an advantage of running the lamp from DC and I suspect that insects can
see 120 Hz flicker.
One more thing about bugzappers with UV or blue lights: These do not do
a good job of attracting houseflies, blue or green bottleflies or biting
mosquitoes. Mosquitoes on the prowl for blood are focusing on what their
targets emit - CO2, sweat odors, heat, any or any combination or all of
these but not attracted much to light or UV that their prey does not emit.
I had experience of bugzappers attracting mainly insects other than what
I most wanted a bugzapper to kill, and this means things that attract
enemies of mosquitoes, such as bats. In my year when I deployed a
homebrew bugzapper with a DC-fed 20-watt "B" blue fluorescent lamp in
springtime, I believe I made a dent in the local population (a goodly
faction of a city block) in the bugzapper-attracted flying insect
population, and this lasted a good 2, maybe 3 months. What I killed was
mostly leafhoppers, and back then I thought this was good since
leafhoppers suck juice out of plants. But now it appears to me that
plants tolerate leafhoppers mostly fairly well (as opposed to other
insects that feed on plants in ways or to extents that do significant
noticeable damage). And in that year (1978) one thing that I noticed in
the summer following my mid-late spring bugzapper deployment was that the
bat population centered on a park almost 2 blocks away stayed closer to
the park as opposed to doing some flying over my block. That summer, on
my block mosquitoes were as bad as ever.
One more thing about bugzappers: I have seen them attract and kill
lacewings. Lacewings are good, since they eat aphids. I have seen aphids
feed on plants to an extent that harms plants. In my experience,
plant-feeding bugzapper-attracted insects are not much of a problem to
anything, but do attract the enemies of the bugs that you want killed
which are not as attracted to bugzappers. And in spring and summer, most
species of aphids do not fly in most areas - in most areas, most aphid
species have several generations per year with only the last significant
generation of the year producing aphids that have wings. Since I never
did bugzapper testing in autumn, I don't even know if bugzappers attract
flying aphids, but in most of the time of year for flying insects in most
areas with winters and flying insects, aphids do not fly.
- Don Klipstein (
[email protected])
