Is achieving your production color a challenge? If so, you are not alone.
Many manufacturers struggle to ensure color consistency across multiple production runs or between manufacturing locations. While there are many factors that can affect color consistency – including materials, dyes, paints, coatings, color communication, and environment factors – one area that is often overlooked is the importance of lighting.
It’s not unusual to hear of a plant operator or quality control professional taking a production sample outside to visually evaluate color under natural lighting conditions. Others may simply assess color next to a window or under a traditional lamp.
If this sounds familiar, your visual color evaluation process could be a key reason for your color inconsistencies and product rejects. It’s time to abandon the ‘trial and error’ method of visual evaluation and add a light booth to the manufacturing floor. For example, viewing color outdoors leads to inconsistent results based on the time of day and the weather conditions. Equality important, if you are evaluating a product under natural light and your customer is evaluating the sample under incandescent tungsten light, the results will be different.
Proper visual evaluation considers how the product will look, when assembled, in each possible location. Incorporating a light booth into your visual evaluation process will ensure a consistent light source. Light booths can simulate colors pre-purchase under store lighting, in a store or show room, and under lighting that represents their final environment. Light booths also help eliminate challenges associated with metamerism, an optical phenomenon in which a pair of samples appears to matches under one light source, but not under another. Viewing samples and products under a variety of light sources will show any color inconsistencies.
Industrial light booths are specifically made to be durable and rugged for manufacturing environments. When using a light booth to verify color and appearance, keep these helpful tips in mind.
Know your limitations. If your eyes aren’t capable of seeing accurate color, there’s not much a light booth can do to help. Everyone perceives or ‘sees’ color differently. Factors such as age, sleep, what we eat/drink and lighting can all affect how people see color. Anyone involved in a visual evaluation program should be tested for color discrimination. The Farnsworth Munsell 100 Hue Test is an easy and effective method for identifying superior (or sub-par) color vision.
Choose the correct lighting condition. Select every light source under which the final product will be seen and evaluate the color. Today’s light booths should provide five lighting sources, including a dual Daylight Options for D50 lighting for print and packaging evaluation, and D65 for industrial applications. The other light sources should include Tungsten (A), UV and fluorescent lamps. Make sure that the fluorescent lamps comply with ISO, ASTM, DIN, ANSI and BSI visual assessment requirements.
Be aware of surrounding lights, colors and objects. Our eyes are constantly processing the light that strikes the retina. It is best to minimize surrounding light when evaluating colors, and to wear neutral colors like white or gray. It is also critical that only the samples being evaluating are in the light booth – the presence of items will impact the assessment the samples.
Properly arrange your samples. Although it depends on the product and material, the general rule is to view samples at a 0°/45° geometry. Light booths make this easy by simply placing the sample on the bottom of the booth, parallel to the light source. When comparing samples, it is best to lay them side-by-side and touching. Make sure to move samples around – left to right, top to bottom – and observe any changes in color. This is especially important for curved or oddly shaped parts.
Look fast. Only look at an object under a light booth for 5-10 seconds, and then glance away. Staring at an object for any longer than that will make your eyes less sensitive to color variations.
Establish evaluation standards. Determine the lighting and process that works best for your company, products, and customers, then write it down and create standard operating procedures. This will ensure that everyone, regardless of shift, manufacturing facility or at a customer site, is evaluating color under the same conditions and processes.
Incorporating a light booth into your visual evaluation process is easy and affordable. More importantly, it can have a big impact on quality control processes by helping managers identifying color or appearance variations early in a manufacturing process. Whether you are viewing textiles, plastics, metals, or other materials, light booths provide the consistent light source needed to properly evaluate color and appearance.
About Tim Mouw
Tim is the manager of the Applications Engineering and Technical Support Team for X-Rite in the Americas. In his role, Tim oversees a team of 20 technical support specialists that help customers improve color quality control processes. Over the past two decades, Tim has taught over 300 courses on color science across North & South America, Europe, Asia, and Australia.