Colors and Spectral Characteristics of Various Fluorescent Lamps

Please note that unless mentioned otherwise for a specific fluorescent lamp with colored glass or other filtering means, the spectrum INCLUDES the mercury lines. The strongest of these are the violet-blue one at 435.8 nm and the slightly yellowish green one at 546.1 nm. Weaker ones are the 404.7 and very weak 407.8 nm deep violet lines, the very weak 491.6 and 496 nm blue-green lines, and the 577/579.1 nm yellow lines.

DISCLAIMER - some fluorescent lamp color names mentioned below may be trademarks of their manufacturers or of companies who have these lamps custom manufactured for them.

White and Somwewhat White Fluorescent Lamps

Colored, Specialty, Aquarium, Actinic, Plant-growing, Reptile, and Ultraviolet Fluorescent Lamps

White and Somwewhat White Fluorescent Lamps

White fluorescent lamps can mostly be specified by a combination of spectral class and color temperature. A few are known by color name alone, but those mostly have specific usual color temperatures and fall into established spectral/phosphor classes.

COLOR TEMPERATURE:

3000K - warm, comparable to incandescent but usually slightly more orange or pink-orange and less yellow than incandescent. Includes "Warm White".

3500K - a whiter warm color about halfway between 3000 and 4100 K.

4100K - plain white, including "cool white". About the color of "average sunlight".

5000K - icy cold pure white, about the color of noontime tropical sunlight. Sometimes looks slightly bluish.

6500K - bluish white, including "Daylight".

Note that these are the more common color temperatures and there are others.

SPECTRAL/PHOSPHOR CLASS:

Halophosphate - these are the original types, which include "Warm White" (3000K), "White" (3500K), "Cool White" (4100K) and "Daylight" (6500K). The color rendering index (0-100 scale) is 53 for "Warm white", 62 for "Cool white", and 79 for "Daylight". The spectrum is extra-rich in yellow and orange-yellow and low on red and green. This causes reds and greens to look darker and duller than normal and skin tones to be pale.

Deluxe Halophosphate / "broad spectrum" - These have improved color rendering but with a compromise in light output. The color distortions are reduced compared to standard halophosphate lamps but although reduced in degree they have the same characteristic. These lamps include "Deluxe Warm White" (3000K), General Electric's "Merchandising White" (3500K), and "Deluxe Cool White" (4100K with a color rendering index of 89). There are even further spectral improvements in this class, including General Electric's "Soft White" (3000K) and their "Living White" (4100K with a color rendering index of 92).

Triphosphor - These lamps have a rare earth phosphor mixture. There are two basic formulations which I refer to as "7" and "8". The "8" is the better one and just about all compact fluorescent lamps use this formula. The color rendering index is in the low to mid 80's. The spectrum has a strong orange-red line at 611 nm, a strong narrow band with nearby narrow secondary bands around 542 nm in the green, and a band in the blue-green. If the color temperature is 3000K or higher, there is an additional broader band in the blue. Osram/Sylvania lamps of this type have color codes D827 (2700K compacts), D830 (3000K), D835 (3500K), D841 (4100K), and D850 (5000K). General Electric lamps of this type have color codes SPX27, SPX30, SPX35, SPX41, and SPX50. Philips lamps of this type include their "Advantage" and "Ultralume" and "TL8" series - with part numbers including 1/100 of the color temperature.

Color distortions of this type of fluorescent lamp are different from those of the halophosphate and deluxe halophosphate types. Greens and some reds tend to be rendered brighter than normal. Skin tones look natural or slightly more pink than normal. Some pure reds may be darkened but most nearly pure reds such as red poinsettia leaves tend to be made slightly orangish.

There is a "cheaper" triphosphor which I call the "7". This includes General Electric SP (as opposed to SPX), Philips TL7 (as opposed to TL8), and Osram/Sylvania's D7 (as opposed to D8). The color rendering index is in the upper 70's.

Several spectrometer plots of fluorescent lamps, especially compact fluorescent lamps, are in Craig Johnson's Fluorescent Light Bulb Spectra Page. An update in that page was noted 12/16/2006 and further updates are likely soon after that date.

Note: The particular spectrometer and sensor model used is optimized for wavelengths from UV to the middle of the visible spectrum, so the plots shown will run a little low in the red and definitely low in the IR compared to other wavelengths present. Some plots show infrared lines of argon that sometimes show up when when a fluorescent lamp is not yet fully warmed up, and as a result at least one compact fluorescent lamp is shown with both cold and hot spectra.

OFF-WHITE BASICALLY WHITE TYPES:

Natural - this is a "cool white" but with a deep-red-emitting ingredient added to the phosphor. The color is a pinkish white that sometimes looks purplish. Some meat display cases have these to make the meat look more red. Some makeup mirrors with built-in fluorescent fixtures have these to make skin tones look more pink.

Cool Green - this is an uncommon one that has a greenish white or blue-greenish white color. It is brighter than "Daylight" but not quite as bright as "cool white".

Colored, Specialty, Aquarium, Actinic, Plant-growing, Reptile, and Ultraviolet Fluorescent Lamps

"*" preceding a specific brand/model/type indicates that I have actually seen in person the spectrum of a working lamp of this type.

Many of these have spectrometer results shown in Craig Johnson's Fluorescent Light Bulb Spectra Page.

* "GREEN" (color code G) is a slightly whitish and very bright green.
The phosphor's spectral output is a broad band with a majority of the output in the 505 to 570 nm range. This band extends visibly into the red.

* "BLUE" (color code B) is a whitish and very slightly greenish blue color.
The spectrum consists of a very broad band extending from approx. 410 nm in the violet through approx. 540 nm in the green. This band extends significantly into the red region, weakening gradually as wavelength increases. With at least one of these lamps, I have seen a minor peak around 415 nm in the violet.

* "SPECIAL BLUE" (color code BB) This may be a Philips specialty. The phosphor specializes in blue output - mostly between 420 and 485 nm with a majority between 425 and 475 nm and the peak is around 445 nm. This lamp has about 60 percent of the lumen light output of regular "blue" but it is at least as eye-catching, maybe a little more.
This lamp has a medical application - treatment of hyperbilirubinemia, or "yellow jaundice". In order to be good for this, the lamp output has to be extremely low on UV output, and it surely accomplishes this. Either the phosphopr or the glass has a UV block ingredient that even blocks at least half of the 404.7 nm mercury line.

Aquarium Lamps:

Aquarium fluorescent lamps serve any of or any combination of three functions:

1. Illuminate aquarium contents in a pleasing manner.
2. Provide light needed for plant growth.
3. Provide special (deep blue and/or violet blue) light needed by live coral.

See below for more specific lamp types (actinic and plant-growth).

Actinic lamps - These lamps generally produce substantial violet, violet-blue, and/or deep blue light needed by live coral. Some of these lamps are also used for some photographic and photochemical industrial processes.

* Hagen "MARINE-GLO" Visible Actinic - This is a very bright and vivid blue fluorescent lamp intended for aquariums with live coral, which need violet-blue and/or deep blue wavelengths of light. The color is less white than the ordinary "blue" fluorescent lamp described above, but slightly whiter and slightly greener than a computer monitor displaying a pure blue screen. It looks at least as bright as a regular blue fluorescent lamp but has a more-blue color that could be useful in signs.
The spectrum consists of a blue band and a green band which merge together with hardly any dip in between. The blue band is stronger, with the green band being just a little more than an extension of the blue band into the green. I suspect the purpose of the green output is to give this lamp a bright appearance or a not-too-low lumen rating - or to illuminate green vegetation more pleasantly than a pure blue lamp would.
The strongest portion of the blue band is from 435 to 480 nanometers, and there is not much below 415 nm. The green band is mainly from 500 to 540 nm. As noted above, the region between 480 and 500 nm is almost as strong as the 500 to 540 nm range. The green band extends weakly into the red region.

* Philips Actinic 03 or Super Actinic 03 (color code 03) - This lamp makes mostly violet and violet-blue light. The color is a slightly dim and not extremely deep violetish blue. I get an irritation/"pressure" sensation when I look at this lamp directly at close range. I have seen this lamp sold for illuminating aquariums with live coral, which require deep-blue and/or violet-blue light. Although this lamp has a "blacklight" effect, this is due to visible violet and not ultraviolet. I suspect this lamp is also used for some photographic/photochemical industrial processes.
The phosphor band's spectrum seems basically confined to the 400 to 480 nM range, with most of the output between 410 and 435 nm. The peak seems to be in the 415 to 420 nm range (bluish violet). There is a very weak spectral line around 610 nm in the red-orange.

Philips Actinic 05 - my knowledge of this one is mainly from the European Philips online catalog, and it shows this lamp producing a broad band of phosphor output throughout most of the UVA portion of ultraviolet and through visible violet plus a bit of a "tail" throughout visible blue. The broad phosphor band peaks around 365 nm. This is different from blacklight types which have a narrower band of phosphor output and usually also dark violet glass tubing.

One application of the 05 Actinic is attracting insects since ones that are attracted to light seem to like broadband light sources producing both blue and UV.

* Coralife "100% Actinic 03 Blue 7100 K" - This lamp seems very similar to the Philips actinic 03 in spectral output and color (I did not test both _of_the_same_wattage_ side by side). The most significant difference between these lamps was the presence of a very weak red-orange line near 610 nm in the spectrum of the Philips lamp. This line was not present in the spectrum of the Coralife lamp. This line accounts for only a fraction of 1 percent of the output of the Philips lamp.
I don't know how Coralife thinks the color temperature is 7100 Kelvin, or if 7100 K is just part of the name of the lamp and nothing to do with color temperature. This lamp is much more blue than infinite color temperature.
Since this lamp is so similar to the Philips Actinic 03, get whichever costs less.

* Coralife "50/50" (50% 6000 K, 50% actinic 03 blue 7100 K) - I saw the spectrum of one that may have been in use for quite a while, but found no actinic blue content beyond that typical of a high-color-rendering-index fluorescent lamp of this color (approx. 6500 Kelvin). The spectrum had the 611 nm (orange-red) and weaker orange and red lines of triphosphor red, the 542 nm narrow band of triphosphor green, and a broad band in the green and blue (mostly 415 to 540 nm) like that of an ordinary blue fluorescent lamp.

* "AQUA" "Volt Arc" "Marine" - This lamp has a purple-white color close to that of most plant-growing lamps, and is roughly as bright as many plant-growing lamps, but is more of an actinic lamp. Use this lamp if you like the color and color rendering effects and need an actinic lamp for live coral. It is not as good at growing plants as other lamps of similar color, and may be almost useless to any plants containing colored substances that block blue and violet light.

The spectrum of this lamp has some red and green "triphosphor" spectral content, namely the 611 nm orange-red line, weaker orange and red lines, and the 542 nm narrow green band. The strongest phosphor spectrum feature is the violet-blue band characteristic of actinic 03 lamps - from 400 to 480 nm, mostly 410 to 435, and peaking around 415-420.

* "Blue Moon" - This is basically a plain blue fluorescent lamp. The color is slightly less green than that of a regular blue, and the spectrum has slightly less green and has a dim red-orange line near 610 nm that plain blue fluorescent lamps don't have. Otherwise, the spectrum is close enough to identical to that of an ordinary blue fluorescent lamp. In my opinion, this lamp is minimally more beneficial to coral requiring actinic blue light than a plain blue fluorescent lamp is.

* Duro-Test "Aquatinic" - This lamp is basically a high-color-rendering-index, largely triphosphor 6500 Kelvin lamp. Its spectrum is basically triphosphor, with the orange-red line around 611 nm, the dimmer orange and red lines, the green one near 542 nm, and the blue-green band around 480-495 nm. The blue-green band has a slightly different shape than usual for triphosphor lamps. There is a somewhat dim, broad band throughout the blue and green range (mostly 415-540 nm), resembling the phosphor output of a regular blue fluorescent lamp. This is instead of the 440-475 nm band normally present in the spectrum of triphosphor lamps with color temperatures 3500 Kelvin and higher.
This lamp probably has a slightly higher color rendering index and slightly better scotopic vision stimulation than that of most triphosphor lamps of similar color temperature. In my judgement, its actinic benefit to coral is hardly to not at all more than that of most triphosphor lamps of color temperature 5,000 Kelvin or higher. I believe it is mis-named and overpriced.

Plant Growing Lamps: (Aquarium or otherwise)

The usual plant photosynthesis using chlorophyl works best from red light. There are two slightly distinct processes that both work best from red light. Both work well from red wavelengths from 610 to 675 nm, and one of them also efficiently utilizes wavelengths up to 695 nm. Most fluorescent lamps made for plant growth purposes usually produce most of their spectral output in the 630 to 670 nm range. These wavelengths are red, and not as visible as shorter red wavelengths in the 610 to 630 nm range typical of fluorescent lamps designed for maximum apparently visible red output. Therefore, plant-growing lamps are not as bright as lamps designed for general illumination purposes.

Since plant-growing lamps produce mainly the light blue light of the low pressure mercury vapor arc and deep red wavelengths, they usually have a light purple or purplish-pinkish color and are noticeably dimmer than white fluorescent lamps.

Although chlorophyl also utilizes blue light, it does not utilize blue light as well as red light. Other photosensitive chemicals such as carotene respond to deep blue and violet-blue light, and therefore some plants may need some blue light for proper health. However, plants will usually get enough of this from the violet-blue 435.8 nm mercury line from any fluorescent lamps that provide enough red light. Use of blue light by chlorophyl may be impaired in a few types of plants by colored substances in these plants that block blue light.

Plants will utilize orange and orange-yellow light, just not quite as effectively as red light. Fluorescent lamps rich in orange and orange-yellow output will generally work, but you may need enough lighting to be distractingly bright since human eyes are more sensitive to orange and yellow light than to the deep red wavelengths that plant lights are optimized to produce.

Please note that lowest-color-temperature ("warmest") tri-phosphor lamps (generally with rated color temperature at or near 3,000 Kelvin) produce lots of orangish red light around 611 nm, and will grow plants somewhat better than other white and near-white fluorescent lamps. These will grow plants almost as well as lights made for plants, but will look brighter.

Lights optimized for plant growth are low on green output, since plants reflect green light and cannot utilize green light well. One side effect is making red and blue objects look extra bright, and making green objects look an extra-deep darker shade of green. Part of the color-enhancing effect is from a relative lack of orange, yellow, and blue-green wavelengths that make green objects look slightly less green, with the presence of some nearly pure (only slightly yellowish) green light from the 546.1 nm mercury line. The shortage of orange and yellow light results in red objects looking vivid pure red. All this results in a general color-enhancing effect which is often considered a desirable side effect of plant-growing fluorescent lamps.

* "Aquarilux" "Aquarium Light" - This is a common model of fluorescent lamp nearly optimized for growing plants. The phosphor spectrum consists mainly of a 5-peak red band, with the major peaks near 624, 632, 648, and 660 nm. Within each of these two pairs, the longer wavelength peak is somewhat stronger. The 648-660 pair is substantially stronger than the 624-632 nm pair, but looks slightly dimmer due to the lower visibility of the longer wavelengths. There is a much weaker peak in the middle near 640 nm.
In addition to the strong 5-peak red band, there is a weak continuous spectrum.

Reptile Lamps such as "Day Cycle" and "Repti-Sun 2.0" - These are lamps with a cooler white color with a color temperature in the 5000 to 6500 Kelvin range and a high color rendering index, as well as ultraviolet-emitting phosphors. There is UVA output as well as UVB output. The UVB content is usually 2 to 2.4 percent of the total output. Please note that the UVB/visible ratio is about 2-3 times that of average noontime tropical sunlight, so your illumination should generally not exceed 1/3 that of tropical sunlight. Otherwise, the spectral content roughly simulates tropical daylight.
Since average high-noon tropical sunlight is approx. 500 watts of visible and UV per square meter and these lamps are approx. 25 percent efficient at producing this, between 500 and 1,000 watts (lamp wattage) per square meter, or 45 to 95 watts per square foot, will give roughly as much UVB as high-noon tropical sunlight. I doubt most life forms want full-blast noontime UVB all day, so you probably want less. For better info, consult herpetology experts who know the needs of your specific pets. Please also note that human skin generally does not want much UVB, and human eyes like it even less.
There are "Repti-Sun 5.0" and "Iguana Light 5.0" lamps. These are of the same brand ("Zoo-Med") and are identical in all specifications printed on the package. I am guessing that they may or may not be different - possibly the Repti-Sun is more of a broad-spectrum type and the Iguana Light may be more triphosphor. (?) Both of these lamps have 5 percent of their total output in the UVB range, slightly over twice that of other reptile lamps.

* Blacklight (color code BL) - This fluorescent lamp has a phosphor emitting UV, mostly near 360 nm. This is the non-filtered type of blacklight. It glows light blue.

* Blacklight Blue (color code BLB) - This is the filtered type of blacklight. The tubing is made of dark violet, UV-transparant glass known as Wood's Glass. The color is a very dim and very deep violet-blue. The UV output and the deep violet 404.7 nM mercury line get through easily. The violet-blue 435.8 nm mercury line is significantly attenuated, but enough gets through for this wavelength to dominate the color of the visible light from this lamp. All longer visible wavelengths significantly emitted from inside the lamp are very highly blocked by the dark violet glass.

* 350BL - This is an unfiltered blacklight similar to the BL, except that a different phosphor emitting mostly ultraviolet wavelengths near 350 nm is used. This phosphor's spectral band has a slight tail that extends detectably to approx. 420 nm in the visible violet.
350 BL lamps are often used in electric bug killers, since the 350 nm range of UV is supposedly more attractive to insects than the 360 nm range. I think the advantge of the 350 over the 360 is in the wider bandwidth of the 350 - I have done a few experiments that give me some indication that insects are better attracted by light sources of wider bandwidth, preferably stimulating both the "UV" and the "blue" of the four types of color sensors in insect eyes.


Written by Donald L. Klipstein.

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