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by Steven D. Johnson
Racine, Wisconsin

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The Science (and Art) of Comfortable Lighting

Figure 11 - Lighting looks okay now, but note the dark
walls... this causes an effect called "tunneling."

I love words and the most recent object of my affection is paralipsis, a word so obscure that my computer's spell check wants to "fix" it. It is a word particularly apropos in the political season, as it describes a literary or verbal technique of drawing attention to something while professing to pass over it. An example might be, "No one is suggesting my opponent is dishonest..." which means, of course, that "I am suggesting..."

Hundreds of articles have been published describing techniques for workshop lighting. Most are either exercising "deliberately concise treatment of a topic, that much of the significance is being omitted" as one definition of paralipsis goes, or the authors are brilliantly encouraging us to look deeper into the subject ourselves, using paralipsis as "a rhetorical device in which an idea is emphasized by the pretense that it is too obvious to discuss."

Regardless, all the articles left me wanting...no...needing more.

One of the better of the dissertations is a chapter in "Great Workshops". The article covers, as do many others, the basics of light measurement (measured in foot candles), the formula for fluorescent strip placement (space rows apart no more than 1.6 times the distance from the strip to the work height, i.e. your bench top), the differences between fluorescent bulbs (T8s, T12s, etc.), and includes a good primer on ballast design. I recommend it as a good starting point. Yet, for truly pleasing, optimal lighting, you need more.

For the few days that the shop was essentially complete, but equally essentially empty, the artificial light from eleven fluorescent strips seemed more than adequate. But with all the equipment on the floor and many tools and cabinets hanging from French cleats around the wall, the lighting became less pleasing.

Figure 12 - Note the shadows on either
side of my phone. This photo was
taken without a flash, so those
shadows are from the overhead lights.

Standing over the workbench, I noticed shadows on two sides of everything lying on the bench. Looking across the shop, there was a bit of distracting glare, and something kept directing my eyes down and toward the center of the room. There was a lot of light, but somehow it didn't seem entirely pleasant. Was my design bad? Did I have too many lights? Not enough? Was it bad Feng Shui? What is going on?

Initially the inclination was to surmise that the cause was my eyes, not the lights. After all, lights are lights, right? As long as there was enough light, according to the formula, and the lights were spaced correctly, according to the formula, all should be well. So it must be that pesky deterioration of the macula, the central part of the retina, that can begin to occur naturally with age and that can be exacerbated or accelerated by a plethora of external factors, including long term exposure to bright sunlight.

It is also true that as we age, our pupils get smaller and less responsive. A smaller pupil does not let in as much light, and the slower response is the reason mature eyes have more difficulty adjusting to changing light conditions. Older drivers often complain about oncoming lights when driving at night. Chalk that up to eyes that are slower in adjusting from dark to bright and back to dark.

There is a condition known as photophobia, which is not, as I thought, an unnatural fear of photographs, but rather an abnormal sensitivity to light. I'm no hypochondriac, but I began to think I might suffer from this as well.

Having had an eye exam only a few weeks ago, a call to my ophthalmologist confirmed there was nothing unusual going on with my eyes or vision. There simply had to be more to this lighting issue than (sorry) meets the eye. Time to dig in and do some research.

Figure 13 - Simply moving the overhead fluorescent strips
closer to the wall provided much needed light on the walls
and eliminated the "tunneling" effect.

It turns out, lighting is a science and a subject far too complicated and extensive to cover in this column. There are countless scions of the subject, a virtual drawer full of doctoral dissertations, and the internet is awash with white papers. Interspersed are thousands of pseudo science papers that are little more than thinly veiled advertisements for products or services. Instead of wading deeply into this murkiness, read on, and I will reveal a few critical omissions from most of the previous articles on workshop lighting and a few cheap, quick fixes that could well make your shop a more comfortable, safe, and pleasant environment. I am now the self-appointed scion of workshop lighting!

Figure 14 - Here a cheap wall sconce lightens a wall and
helps negate some glare from outside light.

The first issue that is seldom, if ever, addressed is described as "tunneling." Rows of lights running through your shop can create "tunnels" of light. If the walls are not also washed with light, this "tunneling" effect can be distracting and unpleasant. The medium-to-light tan walls in the Down To Earth Woodworking shop reflected a good bit of light when the shop was empty, but with the shop full and darker tools, racks, and cabinets hung on the walls, they reflected less and less light. The subtle tendency to look down or toward the center of the room was an autonomic response to this tunneling effect. By simply repositioning three of the previously installed fluorescent fixtures, I was able to throw a little more light on two of the walls and eliminate the problem. This is often referred to as "wall washing" with light. Sconces, up-lights, and even high-intensity spotlights can be used, too.

As many of the articles and literature suggested, I originally aimed for 50 to 100 foot candles of light on work surfaces. A foot candle (FC) is the American way of measuring luminance on a surface. A foot candle equals one single lumen of light density per square foot. I know we have a lot of readers in the metric world, so you will measure light in "lux," which is one single lumen of light per square meter.

Figure 15 - The Luxmeter app on my iPhone.

If you do not have a light meter (and who does?) don't despair. Download a free app for your smart phone or tablet device. The one I installed is called Megaman Luxmeter. It uses the camera in your iPhone, iPod Touch, or iPad and the light through the lens to provide accurate light readings in Lux or FC. There are Android-based applications as well.

The "Great Workshops" lighting chapter recommends 50 FC if you are less than forty years of age, and 100 FC if you are over 40. A bit strict in formula, it shortchanges the subject somewhat. OSHA standard 1926.56(a) mandates a minimum of just 10 FC for "general construction plant and shops" and 30 FC for "first aid stations, infirmaries, and offices." An office design and ergonomics book recommends a whopping 200 FC for offices, and yet another reference recommends 150 FC for surgical suites. Easy to see, even with less than the recommended foot candles, that the subject of light intensity can be confusing.

On my workbench, which is 36 ½" high, my readings were a fairly consistent 56 to 58 FC. On top of the table of my Rikon band saw (at 42" from the floor) the FC reading was in the mid-sixties. My highest reading was at the drill press, which has a high table and where I had also installed some additional spot lighting. The lowest reading was at the mortising machine, whose table is too low at 34" (a situation which I will be correcting soon). At its current height, only 30 FC illuminated the surface. All of this measuring points out the very important factor of distance, light source to work surface. All my fluorescent fixtures measure 96 ½" from the middle of the bulb to the floor, so you can see how even minor differences in work surface height can dramatically impact the amount of light. If you simply need more light in certain areas, and have the space, try lowering the fixtures a bit.

Figure 16 - These spotlights wash the wall with additional
light, dilute the light on the bench to minimize shadows,
and add a few foot candles.

Another factor that will contribute greatly to lighting comfort, or lack thereof, is diffusion. Harsh shadows can create overly harsh contrast that can in turn distract and fatigue, but the total elimination of shadows can harm depth perception resulting in work inaccuracies and even accidents. Take a look at the picture of my phone in "light meter" mode above, and look at the shadows cast to either side of the phone. The shadows were the result of bright, non-diffused T8 bulbs in the fixtures above the bench. We woodworkers don't care much for diffusers. They gather dust and reduce light output, and make it more difficult to change bulbs. In this case, though, a diffuser on the light would help remedy the situation. But there is another way. By adding some additional light from yet another direction the shadows can be minimized through a dilutive effect. In essence, we can dilute the effect of shadows by throwing more light on the object from a different direction. Photographers and videographers do this all the time. But care should be taken that shadows are not eliminated completely. In photography, the total elimination of shadows yields a stark, depthless look.

I have since "repurposed" another light fixture removed from the "Unhandy House" and aimed its three movable heads at the bench, much as I did at my other bench. The difference is amazing. If you cannot adequately diffuse the light, try diluting it.

All of the articles in other magazines do a good job of describing the color output of various light sources. The part they leave out is that the color of the light doesn't really mean much until it hits something. We see objects as a function of the light reflected from those objects. The reflected light has color that is attenuated by the object it strikes. Thus our perception of the color quality of light can be changed without necessarily changing the light source. Think of how the lights looked in your living room before and after your spouse decided to paint the walls that trendy bold blue color.

A well-known kitchen designer told me he never allows a customer to select a finish for cabinets until they take a sample home and look at it, for several days, in their current kitchen. He wants them to see it under changing light conditions and their own changing physiological conditions. Are you aware that your color perception changes from morning to afternoon, in response to your mood, to your blood sugar level, to your hormones, and other factors? It's true.

To achieve truly pleasing lighting is a personal experience, and a little experimentation is in order. I have tried, I think, every color temperature of fluorescent bulb made, and my most pleasing combination is currently a mixture of warm bulbs (3,000 Kelvin rating), cool bulbs (4,200 Kelvin), and a few conventional tungsten filament bulbs. I know, I know...I may soon not be able to buy conventional bulbs, but for now, the miniscule few in my shop are not single-handedly thawing any glaciers and the combination produces color that suits me very well.

Light affects everything from productivity to safety to your general mood. If your shop lighting needs a little tune-up, remember to throw some light on the walls, check the brightness at various working heights and adjust as necessary, minimize (but don't completely eliminate) shadows with diffusion or dilution, and experiment with color, either at the source of the light or by changing the color of some major components of your shop. These fixes will cost almost nothing (except some time) and could help you create a much more comfortable, productive, and even safer place to work.

To see the finished Down To Earth Woodworking shop and some scenes from the move-in, be sure to click on this link for this month's video.

Next month, join me in my gradual re-immersion into the woodworking world as I re-hone my skills with a neat shop storage solution.

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