The Science of Light and Its Impact on Paint Color, Specification, and IEQ

Using artificial and natural lighting to help specify paint for healthy spaces
Sponsored by Benjamin Moore & Co.
By Andrew A. Hunt
1 AIA LU/HSW; 1 IDCEC CEU/HSW; 1 GBCI CE Hour; 0.1 ICC CEU; 0.1 IACET CEU*; 1 AIBD P-CE; AAA 1 Structured Learning Hour; This course can be self-reported to the AANB, as per their CE Guidelines; AAPEI 1 Structured Learning Hour; This course can be self-reported to the AIBC, as per their CE Guidelines.; MAA 1 Structured Learning Hour; This course can be self-reported to the NLAA.; This course can be self-reported to the NSAA; NWTAA 1 Structured Learning Hour; OAA 1 Learning Hour; SAA 1 Hour of Core Learning

Learning Objectives:

  1. Describe how color affects the symbolic, emotional or associative perceptions of occupants, and in turn, their health, safety and well-being.
  2. Explain how correlated color temperature (CCT), color rendering index (CRI), and spectral power distribution (SPD) impact the quality and color of light.
  3. Distinguish the CCT and CRI of different artificial light sources, and describe their effects on color.
  4. Provide examples of how design professionals can use their knowledge of light to create designs that support the health and well-being of the occupant.

This course is part of the Interiors Academy

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Requesting a Drawdown

Sheen is a quality of paint that impacts not only its appearance and durability, but how colors are represented. Typically, color chips are produced using an eggshell finish; however, the same color can appear lighter or darker in a glossy finish. If a project calls for a glossy finish, it is advisable to sample the paint color in the desired sheen to ensure the color is right.

Design professionals can request drawdowns to get a good idea of what the paint will look like in a given space with a certain type of lighting. A drawdown is a sample of paint from the actual color and sheen specified for the job. Drawdown cards usually measure 8 x 11 inches and are made by placing a small amount of paint on a plastic card and spreading it using a metal bar. This method eliminates distracting brush strokes and ensures consistent coverage.


An important consideration when selecting paint is a phenomenon called metamerism. Metamerism occurs when two colors that look identical under one light source look different from each other under another.

Metamerism occurs because the spectral power distributions of these apparently identical colors are different. When two such colors are plotted on a graph showing relative reflectance across all wavelengths, the curves will overlap if they are non-metameric but they will cross or intersect at least three times if they are metameric.

Metameric matches, or pairs, are quite common, especially in near neutrals, grays, gray-blues, gray-greens, and mauve, and the differences can be surprisingly dramatic.

Metamerism typically occurs when matching two colors that are made of different materials—for instance, paint and fabric. This occurs because the paint is colored with pigments, while the fabric relies on dyes.

Recall that colors can be created using additive (light) mixing or subtractive (substance) mixing. Blending pigments is different than mixing inks for printed material or using light to create colors on a computer screen.

Evaluating Paint Color and Ensuring Consistency

Metamerism is a key reason to evaluate color chips under various lighting conditions, including natural daylight and different types of artificial light. Manufacturer color chips are typically produced using an eggshell finish, as this finish is less prone to glare and provides an accurate rendition of a color.

Professional paint retailers typically equip their stores with state-of-the-art lighting technology and light boxes that enable a customer to view paint chips under various lighting conditions.

To properly evaluate color, specular reflection must be eliminated. This is accomplished by viewing color at an angle—ideally, 45 degrees from horizontal. This angle ensures only diffuse reflection is seen. It also eliminates glare, which can distort color.

When color standards are viewed in the lab under specialized lighting in a light box, a stand is used to hold a drawdown on a 45-degree angle to improve color viewing accuracy.

A key point to remember is that color formulas are not the same across manufacturers. For example, one manufacturer may use more green in their formula while another may use more blue. The undertones in the colorant are impacted by the changing light source.

In addition to the range in color formulas, product composition varies from manufacturer to manufacturer. For example, some colorants are made from solvents, which are paint thinners; others are made with waterborne technology. Such resins improve durability and hide without contributing volatile organic compounds, or VOCs.

For these reasons, it is recommended that design professionals indicate on their specification or contractor instructions that product substitutions are unacceptable. This is the best way to ensure that the end result is exactly what the designer or architect intended.

There is more than one way to make the same color. Paint color prescriptions and colorants vary from manufacturer to manufacturer. Some use proprietary colorant systems, while others rely on third-party sources.

Recall that paints exhibit a mass tone, or dominant tone, and undertone. Examine two seemingly identical colors from two different manufacturers, and you may find that one adds more red, while the other adds more yellow. This difference only becomes apparent once the paint is applied and the light source illuminates the surface. The color temperature of the light source effects the undertones in the colorants and may cause a color shift.

Another factor that impacts the tinted color is the quality of the base paint, or the paint before it is tinted. Base paints vary; some are slightly gray or yellow, while others are white. The quality of the base paint also impacts the quantity and distribution of colorant that is used to create the tinted color.


This section will discuss the key factors to consider when specifying paint: Application, Light Source, LRV, and Sheen, and will instruct design professionals how to use paint chips to successfully select paint color. It will also discuss the importance of paint schedules and paint specifications and what each should include. This section will also discuss how specifications can be used to avoid color discrepancies.

As we have seen, artificial lighting sources vary in their ability to render color. It will be important to determine the color temperature and CRI of the light source. Is the CRI adequate for the application? Remember, a CRI of 80 or above is acceptable for most spaces. A CRI of 90 or above will provide excellent color rendering. In many cases, artificial lighting can be supplemented by daylighting. Many if not most colors show well in natural light; however, keep in mind that light conditions change throughout the day and through the seasons, and the color will often be illuminated exclusively by artificial light. Light sources with CCT values around 3000 K will better mimic natural light. Also, keep in mind that higher LRV will increase the amount of light reflected in the room, whether the light source is natural or artificial.

The choice of sheen can make colors appear lighter or darker, so be sure to request a drawdown in the exact color and sheen specified for the job. Remember that sheen tends to impact darker colors more dramatically, and that glossier sheens can cause glare.

LRV and sheen will in part be determined by the building type and function. An industrial or healthcare project will have different requirements for aesthetics, performance, and durability than a residential project.

Finally, the manufacturer’s paint formula will have an impact both on paint performance and on how the color is perceived in different lighting conditions.

Photo courtesy of Benjamin Moore & Co.

Paint Schedules and Specifications

During the design process, much time and effort are spent selecting lighting and color for a space. All too often, however, contractors allow product and color substitutions on the job, often with disappointing results.

Design professionals can use schedules and architectural specifications to ensure the correct products are applied on the right surfaces.

A schedule is a list of materials, fixtures, finishes, building components, or equipment in table form. Schedules can be found on construction drawings, or in the project manual. The purpose of schedules is to avoid cluttering a drawing with too much text, and to quickly clarify the size, quantities, location, finish, etc., of items.

A paint schedule provides an easy to understand materials list for all the paint finishes required for a job. It also helps the painters identify where each color should go. Paint schedules typically indicate a manufacturer, product name and number, a color name and number, and gloss or sheen.

Schedules are an important part of construction documentation. However, a specification is still required to control the quality of the supplied coatings and how they are to be applied. Division 01 defines if and how product substitutions are to be proposed, evaluated, and approved. This is particularly relevant to paint specifications, due to the practice of color matching.

The best way to completely avoid color discrepancies in critical installations is to use a proprietary spec to dictate the manufacturer’s name, product, and color name and number, with instructions not to substitute product and no color matching.


Selecting paint is more than just choosing an appealing color. How a given paint color will actually appear in a space depends on a host of factors, including the lighting type, reflectance, finish, and formulation of the paint itself. Specification can also have psychological and physical effects on occupants of a space. Design professionals can use their knowledge of light and color to select the perfect paint for the given application and can translate their selections into specifications and schedules that ensure the exact product is ultimately used on the job and—ultimately—provides design elements that lead to environmental quality and health and well-being for the occupant.

Andrew A. Hunt is a multi-functional project manager, writer, and musician with over 15 years of experience in multi-media production, instructional design, and content development. Andrew heads the content development team at Confluence Communications (, producing and delivering multi-media material to clients in both the residential and commercial sector.

This test is no longer available for credit
Benjamin Moore & Co. Benjamin Moore & Co., a Berkshire Hathaway company, was founded in 1883. One of North America's leading manufacturers of premium-quality residential, commercial, and industrial maintenance coatings, it maintains a relentless commitment to innovation and sustainable manufacturing practices. The Benjamin Moore premium portfolio spans the brand’s flagship paint lines, including Aura®, Regal® Select, CENTURY®, Ultra Spec®, Natura®, and ben®. The Benjamin Moore Diversified Brands include specialty and architectural paints from Coronado®, Lenmar® and Insl-x®. Benjamin Moore & Co. coatings are available primarily from its more than 5,000 locally owned and operated paint and decorating retailers.


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Originally published in Architectural Record
Originally published in June 2022