Jul 06, 12
Whether you’re shooting at friends in a laser tag arena, venturing through the narrow passageways of a haunted house, or simply watching your favorite episode of CSI, black lights never cease to amaze. There’s something fun and mysterious about revealing secrets and hidden messages with that strange purple light. But how do black lights work? (Hint: It’s not magic.)
The signature glow produced by black lights requires two separate things: A source of ultraviolet light and a surface coated with UV-reactive phosphors. The source of the light is a bulb, whether incandescent, fluorescent, CFL, or LED. You can find phosphors—a loose grouping referring to special compounds and minerals—in and on all kinds of things: Highlighters, soap, rocks, glow-in-the-dark toys, and even your teeth. When ultraviolet light hits a phosphor, the phosphor glows in a phenomenon called luminescence.
Incandescent Black Lights
You may remember from our previous article on yellow bug lights that the short-wavelength spectrum of light beyond visible light is ultraviolet light. All light sources produce UV in varying quantities. For example, the simplest form of black light, an incandescent black light, produces very little ultraviolet light but uses a special filtering glass called Wood’s Glass to block most visible light produced by the bulb filament, thus enhancing the effect of the UV spectrum. However, the relatively small amount of UV light incandescent bulbs produce makes incandescent black lights the least impressive of black lights.
Fluorescent Black Lights: BL vs. BLB
Fluorescent light sources naturally emit much more of the ultraviolet light spectrum, making the technology ideal for use in black lights. Fluorescent black lights fall into two different categories, black light (BL) and black light blue (BLB). Fluorescent black lights use special phosphor coatings on the inside of the bulb to filter out visible light and enhance the emission of ultraviolet light. In both BL and BLB technologies, this ultraviolet light causes external phosphors in its surroundings to glow, just like an incandescent black light does. However, because fluorescent technology produces much more of the UV spectrum, fluorescent black lights are more effective than incandescent black lights.
While both a fluorescent black light and a black light blue use UV light and phosphor coatings to create luminescence, the difference between them is how much invisible ultraviolet light they emit in relation to visible white light. A fluorescent black light, which appears similar to any ordinary white fluorescent lamp, emits a relatively large amount of white light mixed with ultraviolet light. The light from a fluorescent black light looks similar to what we are used to from ordinary fluorescent sources, yet still causes limited luminescence of external phosphors.
Black light blue fluorescents are much more commonplace. Like other fluorescent black lights, they use a special phosphor coating to filter white light; however, for more complete blocking of white light, black light blue bulbs also are made of a purple-colored filtering glass. This combination allows them to emit a greater amount of ultraviolet light than white light. The result is the familiar purple-colored light and a very pronounced luminescence of phosphors in black light reactive objects.
Other Black Light Technologies
Of course, fluorescent black light technology lends itself equally well to compact fluorescent black lights. Though compact, CFL black lights work according to the same principles of black light or black light blue fluorescent lighting. LED black lights are less common, though they are starting to emerge, especially in stage and nightclub lighting. Other niche applications include HID lighting, especially mercury vapor, and “bug zapper” lights like the Paraclipse Mosquito Eliminator.
We hope we haven’t completely destroyed the mystique of black lights for you. But if we have, be sure to let us know in the comments, or drop us a line on Facebook, Google+, or Twitter page.
Jun 29, 12
It’s a long accepted fact that production of the hormone responsible for sleepiness, melatonin, can be suppressed by light. The pineal gland uses the presence of light to determine when to release and suppress the hormone, setting our “internal clock” to a cycle of wakefulness and sleep, also known as a circadian rhythm. Not surprisingly, the large amount of artificial light we encounter in the modern world can have a negative effect on this cycle by suppressing melatonin production even at night. However, recent studies suggest that not just the amount of light, but also the color of the light we encounter may affect our sleep cycles.
A 2005 study conducted by researchers at Kyushu University in Japan suggests that exposure to high color temperature light immediately preceding bedtime reduces the length of stage 4 sleep. In the study, the researchers exposed different subjects to 3000K, 5000K, and 6700K light sources for 6 hours before going to sleep. Researchers monitored the subjects’ sleep patterns and came to this conclusion:
Given that the S4-sleep period is important for sleep quality, our findings suggest that light sources of higher color temperatures may reduce sleep quality compared with those of lower color temperatures.
Other studies by the University of Basel in Switzerland and the University of Connecticut found similar results.
Though these findings are not yet accepted scientific fact, it’s worth noting that manufacturers have already started to create products with these ideas in mind. Philips, for example, produces an entire line of “Wake-Up Lights” that use increasing light intensity and color temperature to wake you from sleep, a method that is marketed as a more natural alternative to alarm clocks. The computer program and smartphone app f.lux reduces the color temperature of screens for less obtrusive nighttime reading. On the flip side, companies have long used “full spectrum” office lighting to increase alertness and productivity, assuming that if high color temperature lighting discourages sleep, it must also encourage wakefulness.
While the scientific community works this all out, what can you do now to improve your sleep? Start with what we do know: Bright light of any color temperature suppresses the production of melatonin, so limit the use of artificial light in the hours preceding sleep. This is easy to do with dimmers, 3-way bulbs, and even low wattage bulbs. Second, conduct your own study: If you currently use high color temperature bulbs and have difficulty sleeping, switch them out for soft white or warm white bulbs and see if you notice a difference.
If you try these ideas out, we’re curious about the results. Does color temperature have any effect on your sleep? Let us know in the comments, or drop us a line on Facebook, Twitter, or Google+.
Mar 09, 12
Despite the media hype surrounding the phase-out of incandescent light bulbs, most news outlets failed to mention that manufacturers will also phase out other popular light bulbs this year. These other phase-outs—which are not part of the EISA 2007 legislation, but rather 2009 US Department of Energy regulations—will affect some of the most popular bulbs on the market today: T12 fluorescent tubes and Halogen PAR lamps.
T12 Fluorescent Phase-Out
The T12 fluorescent tube phase-out has been a long time coming. More efficient T8 and T5 lamp types have all but replaced the once ubiquitous T12 already, perhaps because the standard 4-foot T12 lamp burns a whopping 40 watts, while its T8 replacement uses between 25 and 32 watts. To anyone who has installed a fluorescent fixture in the past 5 years, it’s been a no brainer: Go with the T8 and save up to 60 watts per fixture.*
Here’s a partial list of T12 lamps affected by 2009 DOE regulations:
The DOE regulations also affect some T8 lamps, but those affected aren’t very popular. Though the phase-out doesn’t take effect until July 14th of this year, you’d be hard-pressed to find a T12 lamp in any local hardware store, so you’ll have to check online if you intend to stock up.
The full list of fluorescent phase-outs can be found in this summary from GE.
Halogen PAR Phase-Out
Perhaps more significant than the T12 phase-out is the elimination of most Halogen PAR38, PAR30, and PAR20 lamps. The ban covers most Halogen PARs between 40 to 205 watts. Do you have a PAR38 in an outdoor fixture or a PAR20 in a track light? Chances are, you won’t be able to get either of those after July 14th, 2012 when the ban takes effect.
Fortunately, there’s a silver lining to the Halogen PAR ban. Most eliminated PAR lamps will be replaced with IR Halogens, which have a special infrared coating on the Halogen capsule to redirect heat inward and increase the efficiency of the bulb. This allows them to meet the minimum efficiency requirement of around 18 LPW. Other options include CFL and LED PAR bulbs and even some self-ballasted metal halide PAR lamps.
So what do you think? Are these regulations a step in the right direction, or are they a case of government overreach? Leave your thoughts in the comments section, or connect with us on Twitter and Facebook.
*Calculated assuming a 4-lamp troffer using 25W F32T8 lamps instead of 40W F40T12 lamps.
Feb 10, 12
Unless you’re an electrician, you’ve probably never changed a ballast. Chances are, when your garage fixture or kitchen light went out, you changed the bulbs, and when that didn’t work, you went to an overpriced hardware store and bought a brand-new fixture. Sound familiar?
Unfortunately, you could’ve saved a lot of money by switching out the ballast—an investment of only $10 to $15.
But with so many options out there, how would you know which ballast to pick? The truth is, it’s pretty simple. There are tons of fluorescent ballasts to choose from (we have nearly 300 on our site!), but most business owners and even homeowners will find it easy to wade through that seemingly never-ending selection if they concentrate on just 3 key specs: Bulb type, start method, and ballast factor.
Needless to say, this is the most important part. If you don’t know what type of fluorescent bulb you’re using, you’re going to have a hard time figuring out which type of fluorescent ballast to buy. Fortunately, most fluorescent fixtures will use one of three common bulb types: An F40T12 (4′ long; 1.5″ in diameter), an F32T8 (4′ long; 1″ in diameter) or an F54T5 (46″ long; 0.625″ in diameter). If your bulbs don’t meet one of these descriptions, you’ll need to check the etching near one of the ends of the fluorescent bulb (a good idea even if you think you know the bulb type).
Once you’ve determined what type of fluorescent bulbs you have, don’t burn them out prematurely by choosing a ballast with the wrong starting method. As discussed in a previous article on how to extend the life of a light bulb, an instant start ballast hits the fluorescent bulb cathodes with about 600 volts every time you flip the light switch. As you might imagine, the bulb can only stand so many of those on/off switches. Consider where your fixture is installed. Offices, boardrooms, and retail spaces tend to stay lit for long periods, so use an instant start ballast should be fine, as long as you don’t switch the lights off and on more than about 3-4 times a day. Hallways, stairwells, and bathrooms are switched much more frequently, especially since the lighting in these areas is often controlled by an occupancy sensor. In these areas, it’s best to use a programmed start ballast, which will heat the bulb cathodes more slowly and prolong its life.
Finally, you need to consider light output. “What?” you say. “You mean the bulb isn’t exactly the brightness it says it is on the label?” Nope. The light output shown on a fluorescent bulb’s label, expressed in lumens, is figured using a normal light output ballast with a ballast factor between 0.77 and 1.1. A normal ballast factor is usually the right option, for “normal” circumstances. But if you don’t need your room quite as bright, you can save electricity by using a low output ballast with a ballast factor below 0.77. On the other hand, if you are lighting a warehouse or manufacturing facility where brightness is important, you will need a high output ballast with a ballast factor above 1.1, which will push the bulb to be 10% or more brighter than stated on the label.
Of course, if you need something more specialized like a sign ballast, dimming ballast, or circline ballast, you’ll likely need an equally specialized electrician. The same principles still hold true, however, so if you need to call an electrician, at least he’ll be impressed by how much you know!