A new study on light variation explores when imperfectly matched lighting is OK and when it’s not.

Marilyn R. P. Morgan,
Lighting Research Center

Light sources of the same type are not always exactly the same color. That can cause problems for retailers, who suffer when such mismatches give customers an impression of lower quality.

Even though two lamps may produce white light, one might be a yellowish white while the other might be slightly blue. Such ever-so-subtle differences can make a store look less attractive. Upscale retailers must be especially careful about their lighting in order to maintain their images.

What people involved with lighting need to know is how closely individual lamps must match for a given application so the lamps can be obtained as inexpensively as possible while still producing attractive lighting. Producing lamps with no apparent color differences requires a manufacturing process with close tolerances, which can increase the cost of the lamps.

Just how much variation is acceptable? That depends greatly on the application. For example, if the lamps are close together and directly visible to the observer, a small color variation will be noticeable. On the other hand, if the same lamps are placed far apart, the color variation may not be noticeable.

Because color discrimination depends on the application, setting a general criterion for acceptable color variation for a lamp type may not be appropriate: What is excessive for some applications may be inadequate for others. How, then, can manufacturers and users of lighting products know how much variation is acceptable?

An Enlightening Study

The Lighting Research Center (LRC), based in Troy, N.Y., recently completed a research project in this area. As part of this effort, researchers, including Nadarajah Narendran, Sandra Vasconez, Peter Boyce, and Neil Ecklund, investigated at what point observers perceive a color difference between similar lamps when used in display lighting. “The LRC is working to improve lighting in both homes and businesses,” says Mark S. Rea, Ph.D., director of the center. “Part of that improvement is in the area of cost. Neither lamp manufacturers nor retailers should have to spend more money than is truly necessary to meet the needs of their customers.”

This study simulated the frozen food aisle in a grocery store using a mock-up refrigerator display case with two side-by-side cabinets divided by an interior wall so each cabinet could be illuminated separately. The experimental setup duplicated the light levels of typical freezer cabinets and was placed in a room that had general lighting similar to that of a supermarket. In the cabinets, the researchers placed common frozen food items such as entrees and ice cream. The researchers systematically varied the color of the lighting in one of the two cabinets while keeping the color in the other cabinet constant. Then they asked test subjects whether they could detect any difference.

The research confirmed that a single standard for consistency in color among lamps is not adequate for all situations. “With visually complex displays, such as those that include objects of many colors and lots of fine detail,” Vasconez says, “you find that people have a greater tolerance for illumination from lamps of different colors than they do otherwise.” The color of lamps for refrigerated grocery display cases can vary significantly before customers start noticing a color difference because colored objects inside the cases make color discrimination more difficult.

On the other hand, less visually complex displays, especially those that include white objects, require lamps made to closer tolerances. White objects easily reveal the color of any light that shines on them, so they pose a special challenge in lamp color matching. Lamps used as wall washers, for example, should be closely matched because wall and ceiling surfaces are likely to be white and relatively simple, visually.

Common Mistakes

What should retailers know about buying lighting products for their stores? The most common mistake buyers of lighting products make is not realizing that there are different colors of white. White lamps are broadly differentiated into warm white and cool white. Within these categories are different whites distinguished by color temperature. “Someone who doesn’t know that a 3000-K lamp will be yellow-white while a 5000-K lamp will be blue-white may order lamps randomly and put them up in the ceiling together, and that’s going to look pretty bad,” Vasconez says.

Retailers should stick with a single lamp manufacturer whenever possible rather than buying lamps from many different manufacturers. Two 3000-K lamps from the same manufacturer will probably look more alike than two 3000-K lamps from two different manufacturers. If it’s necessary to buy lamps from different manufacturers, it’s best to use them in applications where there will be visual complexity so customers are less likely to see any difference in color.

Lighting experts usually advise those in charge of maintaining facilities to replace all the lamps in a system together at fixed intervals rather than replacing lamps piecemeal as they fail. This “group relamping,” as the practice is called, can reduce the cost of operating the lighting system by saving on labor costs. It also keeps illuminance levels close to the design value for the facility. Another reason for group relamping is that it avoids mixing old lamps with new. Some lamps, especially metal halide lamps, shift in color as they age, so mixing old lamps with new ones may introduce color differences even though all the lamps have the same color temperature rating.

Vasconez has one more tip for retailers: “Conceal the light source whenever possible, especially if you think the lamps may not be exact matches. Some people will look up at the ceiling, for example, and they may be able to tell that one lamp is more yellow than another, but if the lamps are hidden it will be much more difficult for anyone to see a difference.”

Alternatives to Fluorescents

It’s to a retailer’s advantage to understand how consumers react to display lighting. Retailers can also start investigating alternative ways to light cases: There are other options besides the traditional fluorescents. Technologies such as metal halide lamps, fiber-optic lighting, or lighting-emitting diodes (LEDs) can provide solutions for specific lighting applications. Even though these technologies are notorious for variations in color among lamps of the same nominal type, they can still be used in applications where this variation is not noticeable.

Marilyn R. P. Morgan is a technical editor at the Lighting Research Center. The center is an interdisciplinary center of 40 professionals devoted to lighting excellence.

20 Store Equipment & Design - August 2000

It is well known in the grocery industry that fresh, vibrant colors of top quality flower, fruit and vegetable displays are the number one attraction that brings customers into a supermarket. To optimize the visual impact of their fresh flower displays for as long as possible, retail stores must store the flowers in cool temperatures and protect them from premature damage caused by heat and light radiation. Cut flowers are sensitive to the effects of harsh conditions, including excessive heat, UV radiation and ethylene gases created by photochemical processes. UV radiation from general purpose display lighting contributes to flower wilting and accelerates the decomposition process, shortening the shelf life of cut flower displays.

PROMOLUX lamps are color balanced to reveal the existing natural colors of floral arrangements, resulting in displays with the best possible consumer eye appeal. Installing full balanced spectrum lighting from PROMOLUX Lighting International is a simple way to stimulate sales with spectacular natural color rendering. Moreover, since they are designed to reduce heat and UV effects in fresh product displays, PROMOLUX provides safe and effective lighting and extends the shelf life of retail floral displays.

Visually Appealing Floral Displays and Impulse Sales

“Our response to color is intensely emotional, and flowers can be a catalyst for feelings that stimulate more than just our sense of sight and smell.”

~ Leatrice Eiseman

It is no accident that colorful floral displays are placed near the entrance of supermarkets to greet shoppers as they enter the stores and where the flowers are easily available to every customer. As much as 80 to 90 percent of a supermarket’s total floral sales can be attributed to impulse buying—and the sales technique is most effective when interesting displays can attract wide attention and offer easy access to shoppers. Vibrant colors of fresh floral displays can also be counted on to stimulate impulse buying of other items.

“Color plays a vitally important role in the world in which we live. Color can sway thinking, change actions, and cause reactions. It can irritate or soothe your eyes, raise your blood pressure or suppress your appetite.”

Color Matters,www.colormatters.com/entercolormatters.html

Store designers know that the use of color has a strong influence on consumer decision-making and they count on the strong appeal of colorful flower displays to influence purchasing behavior. “Flowers can enhance the image of a store,”explains Wendy Liebmann, founder and president of WSL Strategic Retail, a consulting firm in New York City that publishes the consumer studies How America Shops. “Consumers walk in to something that is pretty, smells great, and builds the notion of fresh.”

Impulse buying accounts for most supermarket flower arrangement sales. In a relaxed and happy atmosphere, marketers expect that customers wil be more likely to respond to their natural impulses to purchase not only the colorful flowers, but other items as well. PROMOLUX, a pioneer in the field of lamp production technology, adds: “High quality floral display lighting is essential to elicit strong consumer appeal, and PROMOLUX true color rendering is what makes retail floral display lighting effective for marketing.”

Conventional fluorescent lighting that is designed for brightness, instead of defining a full balanced range of colors, usually allows the yellow portions of the visible spectrum to predominate, causing white flowers to appear yellow or greenish, and red flowers to appear brownish.

PROMOLUX, in contrast, utilizes Balanced Spectrum technology, a proprietary phosphor-coating process developed for commercial lighting that not only produces natural, balanced light but filters out damaging ultraviolet, infrared, and harsh visible spectrum wavelengths.

PROMOLUX lamps are color balanced to reveal the existing natural colors of floral arrangements, resulting in displays with the best possible consumer eye appeal. PROMOLUX’s balanced spectrum has been rated with the highest Color Preference Index rating ever tested. CPI ranks colors according to what is most pleasing to the human eye. Under PROMOLUX lamps, all colors are more vibrant and appealing.

Increase Flower Shelf Life

Increased impulse sales with beautiful flower displays illuminated by full balanced color rendering is not the only benefit that PROMOLUX can bring to floral merchandisers. PROMOLUX can also help maximize the benefits of brightly colored displays, by increasing the shelf life of fresh cut flowers by up to 50%, depending on the variety of the flower.

Flowers that look like they have not yet reached their prime and will last a long time after they are taken home are the most appealing and marketable. Shoppers expect commercial flowers to last at least a week, yet it often takes 5 to 7 days for the flowers to reach the retailer once they have been harvested. Floral display cases must be brightly lit for optimal floral merchandising, yet hot spotlights can cause cut flowers to wilt as soon as they are put on display under the lamps. Roses and spring flowers such as daffodils, tulips, and irises are particularly sensitive to heat and light radiation.

UV radiation in floral display cases encourages cut flowers to bloom, triggering them to release higher than normal levels of ethylene gas in a photochemical reaction that stimulates the blossoms to open and eventually decompose. Like a domino effect, the release of ethylene gas causes nearby cut flower buds to bloom, become overblown, and decay prematurely.

Even when some of the ethylene is absorbed from the atmosphere by sachets or filters, the gas is continually being produced by flowers sitting under display case lighting. UV radiation contributes to flower wilting and accelerates the decomposition process, shortening the shelf life of cut flower displays. Increased surface temperatures from display case lighting can also encourage bacteria to grow, causing flowers to ferment and decompose.

Although some heat and ultraviolet light radiated by most floral display case lamps are healthy for living plants, they accelerate organic decomposition of cut flowers. Floral display case lamps that lead flower buds to bloom prematurely, wilt, or ‘blast’and fall off, are responsible for increased product shrinkage and lost sales.

PROMOLUX color balanced lamps prolong the shelf life of floral displays while showcasing them to best advantage due to lower emissions of damaging visible spectrum light and UV radiation.

Beyond superior illumination of flowers on display, PROMOLUX lamps stake their reputation on 86% lower UV emissions than most floral display case lighting. Designed specifically to reduce the effects of excessive heat and UV radiation, PROMOLUX full balanced spectrum lighting is the ideal choice for retail floral and other fresh produce displays.

“An increase in shelf-life of four or five times is common. The general appearance of all products subjected to the PROMOLUX bulb is astounding.”

Holly Sales, Pittsburgh, PA

Draw more and more business with an attractive floral department, and your store can become known as the place to shop for all floral purchases. PROMOLUX Safe Spectrum lighting is the ideal choice for retail floral displays. For more information about PROMOLUX distributors in your area, call 1-800-519-1222 and visit the PROMOLUX website at http://www.promolux.com/ .

A few flower merchandising tips:

• Make sure consumers can easily see available floral displays in your store
• Set up fresh flower displays that are colorful and eye catching
• Maintain displays of flowers only of the highest quality
• Make the floral department accessible and user-friendly with helpful personnel
• Create variety in the department with frequent changes of display design
• Replace items that make a minimal contribution to sales with items that create sales appeal
• Generate interest with displays that tie in with a national slogan or storewide theme
• Use themes that highlight special products and services
• Present attractive merchandising displays on a consistent basis
• Stick to a regular maintenance program for fresh floral display
• Install Promolux color balanced lamps to help maximize appearance of fresh floral displays and minimize waste.

As a demonstration of the best lighting effects for all retail displays, Promolux Lighting International has made available a new interactive computer simulation now featured on their website at http://www.promolux.com/english/color_booth/.

The computer simulation dramatically demonstrates how Promolux lamps enhance lighting design with balanced full spectrum lighting that produces outstanding color and low glare. The innovative online Color Booth is a useful resource for retail store owners and designers when they are selecting store fixtures for illuminating product displays.

The Color Booth makes it easy to simultaneously contrast the effects of traditional lighting products with the full balanced color that becomes possible with Promolux Gold and Platinum lamps. It is immediately apparent how the balanced spectrum lighting can improve the appearance and market appeal of all types of retail goods including fruits and vegetables, baked goods, meats and seafood, as well as fine fabrics, leather, and china.

Fluorescent lamps are usually sold according to a measure of emission levels expressed in degrees Kelvin. A color temperature level is described in terms like warm yellow or cool white with a number such as 3500 K. Lower Kelvin ratings have a warm or red/yellow appearance while higher Kelvin ratings are typically cool or blue/white.

But gauging the quality of lighting for merchandising displays by Kelvin degrees alone is not the best indicator of lighting quality. Promolux Gold and Platinum lamps rate higher than everyday lighting products on the Color Preference Index (CPI) � a photometric scale that expresses the effects of lighting on colors as they are perceived by the human eye. The CPI is a measure of how illuminated products appear to consumers and differentiates between high and low quality light sources that have similar Kelvin degrees or of the same color in the visible spectrum. Promolux full balanced spectrum display lamps have the highest CPI rating of any merchandising lamp on the market.

The Electromagnetic Spectrum

Light is color. Light is defined as the part of the electromagnetic spectrum that is visible to the human eye. The visible portion of the spectrum covers a wave-length range from approximately 380 nm to 780 nm. The human eye regards the green/yellow portion of the spectrum as brighter and the outer blue/red portion of the spectrum as darker. General purpose lamps are designed to focus in the green/yellow portion of the spectrum to provide brightness for lighting offices, schools, warehouses, etc.

Promolux lamps are designed to encompass a full portion of the spectrum. Including the darker colors will give a slight impression of less brightness, but will dramatically increase the vividness of natural colors of the fresh foods or merchandise placed beneath the lamps.

Phosphors are compounds used to coat the interior surface of fluorescent lamps and emit visible light when exposed to energy. Promolux lamps are manufactured with rare-earth phosphors previously used only in television picture tubes and are significantly more expensive that those used in regular lamps. The result is a much stronger red definition at 3850K than a standard lamp of 3000K and much better blues than a standard lamp of 5000K.

Promolux has made it possible to use the full, natural range of colors in merchandising displays without using lamps that produce too bright a light, cause color distortion, or artificially enhance colors for commercial displays.

Visitors to the Color Booth on the Promolux website will see the difference lighting can make and learn how Promolux lighting can be best used for individual applications.

A pioneer of lamp production technology, Promolux Lighting makes specialty lamps for quality commercial displays in all standard sizes and wattages. Market Group Ventures, Inc., the parent corporation for Promolux, is a world leader in providing retail technology solutions for merchandisers.

For information about Promolux distributors in your area, call 1-800-519-1222. Visit the Promolux website at www.promolux.com .

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Damaging effects of ultraviolet radiation and excessive brightness in dairy display lighting can cost dairy retailers plenty from rapid deterioration of product flavor, color and texture. Scientific studies demonstrate that light exposure can cause chemical changes in dairy fats and proteins and diminish the fresh colors and delicate flavors of milk and ice cream. Milk, ice cream and other dairy products will last longer with Promolux safe spectrum display lighting.

Promolux International has drawn on years of research and dozens of field trials to design specialized showcase lighting. Safe Spectrum Lighting was created for the retail food industry to meet the need for increased food safety and improved shelf life for merchandising displays and, of paramount importance to any retailer, always with the best true color presentation possible.

Photo Oxidation in Milk Display Cabinets

Promolux International offers solutions for superior milk and ice cream displays in stores and supermarkets. Minimizing light damage with Promolux can reduce product losses, add significant revenue and help maximize high-margin sales.

The “light struck” or photo oxidation effect on milk has been demonstrated in numerous studies of the effects of natural light and fluorescent lighting in food displays. Milk loses flavor under conventional fluorescent lights and also suffers nutrient losses, including the degradation of riboflavin and vitamins A and D.

One study reported that trained panelists were able to detect an oxidized flavor after only 15 to 30 minutes of light exposure and a consumer test group detected flavor changes after a time period between 54 minutes to 2 hours.

In her paper, New Study Validates Light Blocking Efforts: Teens Taste Light-Oxidation in Milk and Don’t Like It, Kathryn Chapman reported: “Both natural and artificial light can induce quality defects that consumers notice—and don’t like. Light exposure causes chemical reactions in milk that can modify the proteins and fats that are present to produce many negative flavors, ranging from burnt protein (burnt feathers or hair) to cardboard or metallic. The resulting off-flavors are dependent upon various factors such as exposure time, intensity and wavelength of light, and composition of the milk.”

A report from Cornell University confirmed that a “Light-oxidized defect develops in milk as a result of its exposure to sunlight or to fluorescent lighting … common in store dairy cases. Light initiates a chemical reaction in milk that modifies specific proteins and fats, resulting in the characteristic off-flavors.”

The Cornell study explained that photo oxidation can occur very quickly in dairy display cabinets:

“Exposure to sunlight for as little as 10-15 minutes (5 minutes in very intense light) is sufficient to cause the defect and longer exposure times are generally required for fluorescent lighting. The closer the milk is to the fluorescent light source (or the more intense the light), the quicker the development of the off-flavor.

Cornell noted further that milk packaging can provide some protection: “In general, the defect is more common in milk packaged in transparent glass or plastic, though it can also occur in milk in paper cartons if there is sufficient light intensity and exposure time.”

Ice Cream Displays

Milk is not the only dairy product susceptible to light damage in from display case lighting. Photo oxidation can also damage ice cream products in the dairy freezer, since the fat content in ice cream is fairly high. A study published in the Journal of Food Science reported that “ice cream might deteriorate during storage under strong lighting in grocery stores. Light-induced oxidation could potentially cause serious problems in the quality and safety of ice cream.”

Promolux Safe Spectrum Lighting

Promolux lamps emit 86% less UV radiation than conventional display case lighting. Typical fluorescent lamps convert approximately 60 percent of the input energy directly into ultraviolet energy, with 38 percent going into heat and 2 percent into visible light. Damage to sensitive dairy products, fading and discoloration is a result of heat and UV radiation typically found in fluorescent lamps.

Promolux offers milk and ice cream retailers cost effective options. Safe Spectrum lighting is food safe balanced spectrum light is and is designed to improve the marketability of perishable goods in two important ways: by reducing the levels of harmful wavelengths of the color spectrum and by minimizing damage to foods displayed for sale to the public. Using Promolux color balanced, low radiation lamps results in improved food safety, reduced rates of spoilage, and visually attractive food presentations.

Scotty Davenport is one of many enthusiastic store owners who use Promolux balanced spectrum lighting for true color definition and food safety. He states:

“I started looking for better lights because on our ice cream we were constantly getting a frost buildup and high condensation. I found Promolux on the Internet and they gave me the name of a distributor in my area. When I put Promolux bulbs in my case, I no longer had any trouble with frost buildup or condensation.

“And with Promolux—customers often comment to me that the colors of my ice cream are so bright and vibrant—no matter which flavor. I am in the process of opening another store, and let me tell you—one of the first things I am doing is yanking the regular bulbs out of my case and replacing them with Promolux!”

The quick solution for effective milk and ice cream displays is to switch to Promolux. All you need to do is replace your light bulbs. For information about Promolux distributors in your area, call 1-800-519-1222. Visit the Promolux website at www.promolux.com and www.safespectrum.com .

References

New Study Validates Light Blocking Efforts: Teens Taste Light-Oxidation in Milk and Don’t Like It. Kathryn Chapman. Dairy Foods (Sept. 2002).

Light-Oxidized Flavor Defect of Milk. Dairy Science Facts 2002. Cornell University.

Photooxidative Stability of Ice Cream Prepared from Milk Fat . M. Shiota, N. Ikeda, H. Konishi, and T. Yoshioka. Journal of Food Science, vol. 67, no.3 (2002).

Scotty Davenport is the owner of The McCall Candy Company, ID