Safe, Legal, Blue...But Are They Any Good?
What's the Scoop on "Extra White" Bulbs From Reputable Manufacturers?
You're asking about the current crop of bulbs, widely available in auto parts stores, with a blue absorption filter on the bulb glass, which is there to make the light look whiter. These bulbs are generally safe and legal, though not advantageous, to use in your car.
Some people feel that "whiter" light is better. Some people prefer the appearance of the headlamp when fitted with these bulbs. And then there are the True Believers, who ascribe all kinds of magical (and imaginary) benefits to "whiter" light.
Some companies (PIAA...) even capitalize on this by claiming that their 55W bulbs are as bright as 85W bulbs, among other pseudoscientific claims. Here's how this claim works: Higher-wattage bulbs of a given type generally appear whiter than lower-wattage bulbs. Think of the last time you replaced a 60W bulb in your home with a 100W bulb. So the idea with these "blue" filtered bulbs is to have a lower wattage bulb that mimics the color of a higher wattage bulb, but not its performance. However, there's no getting something for nothing. The altered light color does not mean you're getting more light, or better quality light, just that the light is of a different color.
In fact, you get less usable light from such a bulb than from a regular clear bulb, and here's why: A blue filter removes nonblue components of the light passing through it. Halogen bulbs produce very little light in the blue frequency range. When you put a blue filter on the bulb or lamp, you are reducing the amount of usable light that gets from the glowing filament to the reflector, to the lens and from there to the road. Prove it to yourself using nothing more than the windshield in your car...drive towards a yellow-orange Sodium vapor street light and watch the light as it shines first through the clear portion of the windshield, then through the blue strip at the top. Up there through the blue, it certainly looks "whiter"...but it's also dimmer. If a bulb's sales material focuses on the color of the light rather than the amount of light, you should ask critical questions about the amount of light the bulb produces before choosing to use it.
But If That's True, Then How Come These Bulbs Have All The DOT and ECE Approval Markings Saying It's OK To Use Them On The Road?
The name-brand "extra white" bulbs mostly produce legal light output, true. But there's a lot of wiggle room in the bulb standards that permit two bulbs of the same format to put out significantly different amounts of For illustration of the principle, take a standard HB5 (9007) bulb, which is legally required to produce 1000 lumens of light from the 55W low beam filament at 12.8v, plus or minus 15 percent. That means that in order to be legally certifiable as conforming to Federal standards, a 9007 bulb in the low beam mode must produce between 850 and 1150 lumens. Most folks want to see better at night, not worse, and the way to do that is to use bulbs that produce the maximum legal amount of light. On a dark road, I want bulbs producing 1150 lumens instead of 850, how 'bout you?
So now, where do these legal "blue" bulbs fit on our 850 to 1150 lumen range? Most times, this information isn't available, for it's often made unavailable by bulb manufacturers. Some of the bulbs come with specification sheets giving a wattage and lumen rating, but these don't list actual output, they simply list the nominal specification contained in the Federal standard. The assumption they want you to make is that the bulb you're holding in your hand actually produces the nominal amount of light. In most cases, with blue glass, they don't. About all that can truthfully be said is that they're safe, they're legal, they're not dangerously poor performers like illegal blue bulbs are, but they do not give an actual performance improvement.
So If Blue Filtration Steals Light, How Do They Still Make These Bulbs Produce Legal Output With The Blue Filter?
The manufacturer optimizes the bulb's efficacy through filament and gas-fill technology, so that the uncoated bulb performs up near the top end of the allowable output range, or even slightly above the maximum allowable output. But the bulb is blue, which "steals" some of the light. If the bulb is designed to produce within the legal light level without the blue, the presence of the blue bulb will reduce the output so it's closer to the bottom end of the allowable output range. If the bulb is designed to produce slightly over the legal light level without the blue, then the bulb will perform nearer the middleof the legal range. Here again, though, we can't have something for nothing.It took reputable bulb makers quite a bit of research and development to produce blue filters that would not drop the bulb output below the legal minimum while still altering the appearance of the operating headlamp enough to appeal to consumers after a "whiter" appearance to their headlamps. The cost? Bulb lifetime. The filament changes made to produce enough extra light that the bulb will still be legal despite the blue-filtration losses mean the filament's lifespan is shortened considerably.
Here's actual data for for output and lifespan at 13.2v for H1 bulbs. The numbers here are a composite of values applicable to the products of the three major manufacturers' bulbs. Each maker's product in each category is slightly different but not significantly so, and while the absolute numbers differ with different bulb types, the relative comparison patterns hold good for whatever bulb type you consider. Lifespan is given as Tc, the hour figure at which 63.2 percent of the bulbs have failed:
|H1 Bulb Variant||Output Lumens||Life Hours|
|Standard (plain)||1550 lm||650 hr|
|Long Life||1460 lm||1200 hr|
|1680 lm||400 hr|
Ultra High Efficacy
|1750 lm||350 hr|
|1380 lm||250 hr|
Part of the impetus for the development of these bulbs was for the makers of good-quality bulbs to take away a portion of the dangerous "crystal blue" (spark blue, 8500K blue, etc.) type bulb sales and satisfy consumers desiring a different headlamp appearance with a legal and safe product. The retail-level marketers have an easy sell here; Pep Boys offers a "Silverstar Upgrade" service for fifty bucks, for instance. And there are always going to be people lining up to offer glowing testimonials about how much better they think they can see with these bulbs. But can they really?
There's no good evidence that the type of light produced by this sort of bulb actually allows drivers to see better than the type of light produced by a regular, clear bulb. And there've been no studies on the effect of this type of light upon seeing and glare in bad weather, for instance. It has, on the other hand, been shown that these bulbs cause more glare than clear bulbs. Can you see better with this sort of bulb? No, probably not. Some people vigourously defend blue-glass bulbs, insisting they can see better. But that's another problem: they think they can see better than they actually can. There've been no studies to determine exactly how dangerous it is to think you can see better than you really can, but it probably doesn't help safety.
It should be mentioned that while these are critical questions that ought to be asked, they are academic to some degree if what you're deciding is whether to use a no-name bulb or the product of a reputable manufacturer, such as Narva, Candlepower, Osram, Philips, or GE.
OK, So These Extra-White Bulbs Aren't The Best Choice For Maximizing My Headlamps' Performance. What Should I Get Instead?
For those who want the best possible performance from their headlamps and are more concerned with their ability to see rather than the appearance of their headlamps, the major bulb companies offer optimized bulbs without the light-stealing blue glass. Narva RangePower+50 and RangePower+30, GE Night Hawk, and Philips Vision Plus, and Osram Silver Star are the ones to get.
Wait a Minute, Earlier You Said Silver Star Bulbs Have Blue Glass!
It's a name game: Osram, the well-established German lampmaker, sells a line of automotive bulbs they call "Silver Star". These are Osram's top-of-the-range headlamp bulbs, equivalent to Narva RangePower+50, GE Night Hawk, Philips VisionPlus, and Tungsram Megalight Premium. They produce the maximum legal amount of light while staying within legal power consumption limits. They have colorless clear glass.
Osram bought the well-established American lampmaker Sylvania in the early 1990s, so Osram is now Sylvania's parent company. Sylvania also sells a line of automotive bulbs they call "Silver Star", but it's not the same product. The Sylvania Silver Stars have blue glass. Light output is of legal levels, but as with all blue-filtered bulbs, you do not get more light from them. The Sylvania SilverStar bulbs have a very short lifetime, because the filament is overdriven to get a legal amount of light despite the blue glass.
To get the best possible seeing performance at night, don't choose extra-white bulbs.Daniel Stern Lighting (Daniel J. Stern, Proprietor)
Copyright ©2005 Daniel J. Stern. Latest revisions 10/12. No part of this text may be reproduced in any form without express permission of author. Permission to quote is granted for the purposes of communication with the author.