Good lighting is made up of a number of components — uniformity, intensity, color, reflectivity of fixtures, to name few — and good lighting is necessary to produce good working conditions.
There are two main considerations when evaluating spray booth lighting:
- What characteristics are important in evaluating light
- How we provide the light with the various types of fixtures available
Too often, when looking to upgrade a painting facility, lighting is not given the proper consideration necessary to provide for the quality finish results the end customer expects, or to meet what the competition offers. The result is a constant battle with the application professional who is asked to meet the standard in a poor environment. This information can help you become more familiar with the terms, how they apply to the situation, and how they can be used in specifying a finishing environment.
The selection of the right design can be challenging with the range of information one must know to make the right choices for a particular application. Using a lighting professional would be one way to make sure that the operation’s needs are met, and that the design is developed by someone “in the know”. If they are not using the terms described here, there might be a question of their understanding of what’s right for the operation. Too many see lighting design as “just provide lots of light fixtures”. The result could be disastrous for everyone. Now, let’s learn more about the technical basics.
Qualities of Light
In 1676, Sir Isaac Newton discovered that color is a component of light, not of the object being seen. By passing sunlight through a prism, he discovered the full spectrum of color and identified seven distinct hues: red, orange, yellow, green, blue, indigo, and violet. The colors that we see are simply a reflection of a particular portion of the light that strikes an object. The portion of light that is not seen is absorbed into the object to become heat. Without light, color does not exist. A full-spectrum light source is necessary for any type of color analysis.
Light is a form of radiant energy belonging to the electromagnetic spectrum. The sun, earth, and other heavenly bodies radiate electromagnetic energy. The electromagnetic spectrum is a continuum of all electromagnetic energies arranged according to their various frequencies and wavelengths. The frequency of a wave is the number of complete cycles it makes in a single second and is measured in Hertz (Hz). Wavelength is the distance from peak to peak of the wave and is typically measured in meters. X-rays, microwaves, television and radio waves are all portions of the electromagnetic spectrum. Visible light accounts for the smallest portion of the electromagnetic spectrum ranging in waves of 380 to 760 nonometers (nm).
The higher the frequency of the wave, the greater the energy level. The specific length of the wave also determines its color. Waves of different color, therefore, have different levels of energy. The wave lengths found in visible light correspond to the following hues:
- Less than 480 nm – blues
- 480 to 560 nm – green
- 560 to 590 nm – yellow
- 590 to 630 nm – orange
- 630 to 700 nm – red
Some hues are not naturally found in the visible spectrum. For example, mixing red and blue, which are at opposite ends of the visible spectrum, produces purple and magenta. White light is achieved through a balanced combination of light waves differing in color. Blending red, green and blue light will create white light; hence, these three colors are considered the primary colors of light.
When two primary colors combine, a secondary color is produced. Yellow light can be produced through the combination of red and green. Combining green and blue light produces cyan. White light will be produced when secondary colors are superimposed.
By contrast, the mixture of color pigments is an example of the subtractive principle.
Here the primaries are yellow, cyan, and magenta. When combined, these three pigments produce black.
Subtracting colors from black produces new colors. White represents an absence of color. A black body will absorb any color of light; similarly, white objects reflect all light. Colored objects absorb light of different color and reflect light of their same color. Thus, in order for an object to appear a particular color, that color must be contained in both the object and the light it is viewed in. This is important since light waves themselves are not visible, but their reflection or emissions from surfaces are.