Spray booth lighting can affect your work in many ways. Learn the details to ensure you?re seeing things clearly.
Have you ever thought to yourself, “I sure wish someone could do something with the lighting in this spray booth”?
Most spray booth manufacturers and their representatives rarely mention booth lighting in their proposals or accompanying literature. Sometimes they will state how many fluorescent fixtures they offer (usually less tubes) and that’s about it. But what many of us could use are some straight facts about lighting to help us make better decisions about our spray booths.
During my days as an automotive spray booth salesman, I would usually ask that, if possible, the painter sit in on the meeting with the prospective customer and myself. To me, his or her opinion was by far the most valid. Who better to know what to ask or look for than the very person who would be spending the most time in the booth. And guess what? The request I heard the most was “Can I have more light?” This was almost always the case of automotive booths, be they in a dealership, independent body shop, trade school or municipal service garage, the amount of lighting was nearly always considered insufficient by the people using the booth. What is sufficient light? How does one measure the light to determine its value?
Types of Booth Lights
There are basically two different types of booth lighting available, one is fluorescent and the other is high-intensity discharge or (HID). Early automotive spray booths were simply closed versions of industrial walk-in style booths. The lighting in the industrial booth was almost always fluorescent and located in the ceiling. But fluorescent fixtures in the ceiling would not cut it for an enclosed automotive booth—more fixtures were needed, especially in the walls. Early single-skin or non-oven booths offered eight fluorescent (four-tube, 4-ft. long) fixtures as standard. Options allowed the buyer to add two to four more fixtures for better lighting. HID lighting was seen as a way of reducing the number of light fixtures to four while still maintaining light similar to eight fluorescent fixtures.
Incandescent lamps have never been considered for automotive booth lighting for several reasons. For one thing, they are the least efficient of all types of lighting due to their high power consumption. It would take a tremendous amount of lamps to equal nearly any other type for light output. This would also produce an enormous amount of heat, which would not only be undesirable, but unsafe as well. They have a very short life, anywhere from 500 to 3,000 hours. They do, however, have excellent color rendering.
These days, fluorescent lights are the most popular and commonly used lamps for automotive booth lighting. They are available in a complete line of color combinations. They produce very low heat and have an extremely long life of 20,000 plus hours.
Commonly called a “parking-lot light,” HID lights are especially efficient. They have a long warm-up time and as such, are very slow to light up. They deliver a large amount of light, allowing some booth providers to install only four each in a booth, usually at each corner. They have a long life of between 5,000 and 24,000 hours. They tend to have a spotlight effect, making them somewhat uncomfortable to work under. Color rendering isn’t bad, but there isn’t much to select from for improvement.
A closer look at fluorescent lights
Fluorescent lamps have long been the most popular choice in refinish spray booths. Let’s take a look at the details of fluorescent lighting. First, the “T” followed by a number that describes the bulb, such as T-12, refers to the diameter of the fluorescent lamp and is measured in one-eighths of an inch. A T-12 would equate to 12 eighths of an inch or 1 1⁄2 in. in diameter. Similarly, a T-10 would be 10 eighths of an inch or 1 1⁄4 in. in diameter and a T-8 would be 8 eighths of an inch or 1 inch in diameter. The lengths of the tubes vary, with 4-ft. and 8-ft. long being the most common.
Fluorescent lamps are available in color temperatures ranging from warm (2,700°K) “incandescent-like” colors to very cool (6,500°K) “daylight” colors. The most common fluorescent lamp color (4,100°K) is “cool white.”
Just how bright is the lighting in my booth?
Everyone knows that it is important to have good and sufficient lighting in a paint spray booth, but there is very little to officially say just what is good. The most quoted source for spray booths is The National Fire Protection Association (NFPA) bulletin 33, but it says nothing on the subject of lighting. This probably explains why booth manufacturers rarely mention this matter, let alone use it in a sales brochure. Booth manufacturers will state just how many four-tube fluorescent fixtures they do offer in any of their line. In all fairness, though, most booths are sold and shipped “less fluorescent tubes.” This has been a common practice for decades, because it is costly to package and ship glass tubes and not have breakage. So it makes sense that if you don’t provide the lamps (tubes) you can’t vouch for the resulting brightness in the booth. For this reason, it is necessary for the shop operator to understand lighting measurement when specifying and sourcing bulbs locally.
The brightness in any booth is measured in footcandles. According to the Illuminating Engineering Society (IES) the recommended amount of light level for a paint spray booth is 100 to 150 footcandles.
The proper way to determine the light level in footcandles in any spray booth is to measure it with a light meter. They may be rented from your lamp supplier or you may wish to buy one from your electrical supply or photography store. They aren’t all that expensive (under $200) and can, of course, be used in many places around the shop and office areas.
Light fixtures
As NFPA-33 requires, light fixtures are fitted over sealed tempered glass in booth ceiling or wall panels (18-gauge mild steel) and are suitable for illuminating direct spray painting (class I—division I) conditions. The fixture itself may be an open fixture as it is glass sealed from the painting activity. Areas around door openings are considered class I—division II or non-direct spray activity. Light fixtures in these areas are to be vapor-proof because the fixture itself can be contaminated from vapor escaping from an opened door. These fixtures are approved for spray booth use. NFPA-33 does state that no light fixture be placed and wired inside the booth. Nor does NFPA-33 use the word explosion proof. Light fixtures that are gasket and glass sealed and are mounted in the booth walls or ceiling are acceptable.
The term explosion proof is a term that is terribly misunderstood. It means that any electrical device that is rated as being explosion proof can survive an explosion and still function. Electrical devices that are rated as being explosion proof are to be used in, according to NFPA, grain elevators, where dust is constantly present and can cause an explosion to occur. Similarly, they are used in waste treatment plants on electric pumps that are in sumps where the threat of methane gas is constantly present. Should an explosion occur, the pump’s electric motor needs to continue to function—thus it is explosion proof.
If a paint spray booth had the chance of having an explosion, you certainly would not put a human being (painter) inside along with an explosion proof device and wiring .
Need more light? Add more fixtures
The main reason that most booths don’t have more light fixtures is cost. When a booth manufacturer needs to lower its booth price, light fixtures are the first thing to go (along with quality filters). Let’s face it, many people buy purely on price. But too few light fixtures is not the end of the world, they can be added. Good fixtures that are similar to what’s already in place and are approved for spray booths along with a reputable mechanical contractor should work.
The best place to position new light fixtures is to ask the painter where more light is needed. My bet is that it will be the lower side walls, especially near the floor to help illuminate rocker panels and the lower portion of the vehicle being painted. We are talking of fixtures that are fluorescent type and accommodating tubes T-8, T-10 or T-12. Any HID or other similar type of lighting will not be so easy to improve as the fluorescent type.
What lamps to choose?
The question “What lamp should I choose?” must be answered by the spray booth user. Following are some common questions and answers:
“All we want is brighter light.” Here you need only to shop for lamps that are high in wattage and/or in lumen output. Usually, lamps in the T-12, 4-ft. long and 40-watt range that are high in lumens are also lower in CRI ratings.
“Do we need color correction in our lamps?” Has color matching been a problem? Does your shop have the ability to alter or change the color formula? Do you have a paint mix room? How do you buy your paint, in bulk or premixed per job? These questions can help determine just what kind of lamps are needed and where they are best suited for.
“What about stress and fatigue?” The CCT of a light source is becoming more recognized as a key contributor of “stress and fatigue,” especially where older employees are involved. “Warmer” light (3000°K or less) is a “friendlier” light to many people, especially when confined to a limited space for long periods of time, like a spray booth or an office.
Here is where I recommend you to get some help in analyzing your shop and your needs from your lamp supplier and/or the manufacturer of lamps that they represent. Again, I can’t overemphasize the importance of sitting down and discussing this first with your painter and shop manager.
Getting help and/or a learned opinion of your lighting needs will get you closer to solving your problems, as opposed to simply guessing or being “sold” something by an eager and aggressive sales person.
Helpful products and tips
Portable light devices. Portable light devices can be a great help in matching colors and not having to rely on your spray booth lighting. Usually the portable lighting is truer to preferred daylight and is different from the spray booth’s lighting. This gives a distinct advantage without a large cost to consider. A portable correct light source also has the advantage in that it can be used anywhere, booth, shop or mix room.
Booth paper. Booth paper is normally considered for maintaining a clean floor during booth operations. While that is true, it also offers a good white surface to help the booth’s lighting. A non-white floor absorbs light; you don’t want this.
Painters like to test their spray guns on a vertical surface other than the item to be painted. This is usually done on the booth’s wall. A strip of white booth paper, taped to the wall provides an excellent vertical test surface. Replaced from time to time it will keep the booth bright, shiny and clean.
Keep the booth walls and glass clean. Strippable coatings are a great booth product to consider. Let’s face it, a lot of atomized paint flies around during spray painting and a great deal of it finds its way onto the booth’s walls. The best way to keep a booth’s walls clean and bright is to coat them with a flat white strippable coating. When they show signs of wear they are peeled off like a sheet from a tablet. Some suppliers also offer the coating in clear for the glass over the lights. This certainly beats scraping with blades. Again, simply pull a corner up and tear the coating off.
There is also a clear plastic film that clings to the glass and can be torn off when it is soiled. Some are even offering a pack of clear plastic covering that allow one to tear off a sheet and expose the next clean sheet, kind of like a cartridge of ammo.
Maintenance
A clean and uncluttered booth means there can be good airflow, which helps carry the unwanted overspray to the filters. Unwanted overspray kept off the booth keeps it clean. A clean booth means better and brighter light to see and work by. The better the condition in the booth, the better the job done in the booth, and it all comes back to that magic word maintenance.
I have seen an awful lot in my travels regarding booth maintenance and a good bit of it was less than good, in fact a lot of it was terrible. In body shops, training and tech centers, and in trade schools, the picture is repeated over and over. Paint overspray so thick on the walls that it can be pealed off. The glass over the lights painted over making the booth a dark cave. With these situations cleaned up, in nearly all cases, it was like adding extra lights in the booth.
