Spraybooth Lighting: Theory and Practice

Automotive spraybooths are the “operating rooms” for the refinish process. These specially built chambers prevent others in the workforce from exposure to harmful materials, provide clean, filtered air and are illuminated so technicians can perform quality repairs. The new modern booths can also supply constant controlled heat, adjust temperature at pre-set times and turn off automatically.

Today’s automotive colors, based largely on cosmetic and clothing trends, have become increasingly difficult to match. Pastel, pearl, mica, color change, ultra-thin basecoat and various clearcoat textures all contribute to this difficulty. However, the best technician with superior technique and experience cannot match colors without proper illumination.

Technicians must also realize that there are some outside factors that can destroy the best material, technique, equipment and lighting. Signals from the color receptors on the back of the eye to the brain via the optic nerve are distorted by outside influences. Nicotine, caffeine, alcohol, carbon monoxide and certain drugs impair these signals and can affect your color vision for up to six hours. Strong coffee, cigarettes and heavily caffeinated sodas are the worst. So skip your morning double latte if you have a difficult color to match first thing.

For years, owners and managers have complained about painters not being able to properly and consistently match colors. Painters, in self-defense, would blame the paint brand, switch paint supplies, and then still had the same types of problems. This condition is still prevalent, and when asked about the lighting system the shop owner’s reply is generally, “There is plenty of light.” Although this is usually true, it isn’t the right light.

How do you get the right light to achieve the correct color match? Color matching is a science requiring knowledge, skill and the proper tools, one of which is proper lighting. The “Theory of Light” is quite simple.

We see the color of an object by the reflection of certain light waves. The object absorbs the other colors. These reflected waves are also influenced by the following: the source of light illuminating the object; the painter’s ability to see true colors (color vision is something we are born with and cannot be changed or corrected); and further variations of color resulting from the addition of various pigments, metallic or mica in the paint. So let’s look at the theory of light and color.

The Light Standard, or the basis for measuring all other light sources, is daylight or sunlight. However, never try to match a color with direct sunlight. Sunlight is the hottest light source. 

Metamerism means that different light sources will make one color look completely different. A medium blue will look almost purple under a mercury vapor street light. Some violet will be brought out with fluorescent lamps, and a simple incandescent bulb can bring out the green in this single color.

Color Blindness is a physical condition that we have to live with. The shape of the “cones” on the back of the eye are like a prism, splitting the light into colors. Depending on their out-of-shape angles, they can give false readings. Color deficiency and vision vary depending on sex, race and age. Color vision can deteriorate with age and accelerate with continued exposure to bright lights such as welding rays, halogen rays, direct sunlight and certain drugs.

Color Rendering Index (CRI) is a scale that relates or indicates a light source’s color balance in relation to natural sunlight. Sunlight has a CRI of 100. Most artificial lighting will only achieve a CRI rating in the area of 50-60. 

High-quality color corrected bulbs for spray booth use should have no less than an 85-90 CRI rating.

The Color Standard is the vehicle’s color. Again, when checking the color against the vehicle, ask the question, “Is the car _____________? a). lighter/darker, b). bluer, redder, yellower or greener, and c). cleaner crisper or dirtier/less brilliant. 
Lumens, or intensity of a light source, are the rating of how strong the wavelength is. Lumens do not produce heat and can be more closely related to candlepower. High-quality color photography requires a lumens rating of 6,500-7,500. Quality spraybooth lamps should be in the area of 4,000 lumens.

Wattage is the energy used to illuminate filaments within a light unit. Most booth-style bulbs will be 40 watts. The important factor is not just brightness, but intensity.

Reality and Shop Practice
Poor color matching seems to never go away. Painters have the best products and materials, high technology spray equipment, quality abrasives, superior masking supplies and state-of-the-art spray booths, yet the basic problem of poor lighting still exists.

We know that almost every job in the shop will need paint repair, and that only about half of the jobs require a full frame machine and measuring system. Yet little consideration is given to the basic lighting. Shop owners have been stepping up and purchasing modern spray booths and yet go to the local hardware store and buy the cheapest bulbs for illumination. This makes as much sense as buying a fast, high-performance sports car and filling it up with cheap, low-octane fuel.

Consider the normal struggle of your painter to make sure the color matches: mixing, checking, tinting, spraying a test sample, tinting, spraying and then finding that the color does not match when the vehicle is taken outside. When the cost of quality illumination is broken down as in the chart above, its clear that quality illumination is a smart investment. Using the numbers in this chart, it will only take 41 minutes of time a month to justify the additional cost of the best bulbs. Eliminating one redo will more than pay the monthly cost of the bulbs. 

Better yet, if the painter has the proper lighting, how many hours of production can be increased, improving cycle time and the bottom line?

Oftentimes in business, the best way to make money is to spend it (wisely, of course). 

Available Lighting Units
Check with your local PBE jobber/supplier or a local lighting specialty distributor for proper lighting units. 
For existing spraybooths, replace all of your current bulbs with those of at least 40 watts, 4,000 Lumens, and a CRI rating of at least 85.

Consider a portable color matching light unit. These may be as large as the one pictured, or smaller and vertical in design.
Cover the light fixtures with a “glass overspray protective film” that acts like shrink-wrap and keeps paint overspray off of the protective glass.