by [TC]²
Tips for Choosing the Right Spectrophotometer
for Today’s Needs and Tomorrow’s Challenges
A white paper by GretagMacbeth
By Michael M. Beering, Product Marketing Manager
If you think a spectro is just another measurement instrument, then think again. Today’s spectrophotometers not only measure color, but they can enable Enterprise Color Management (ECM) on a global scale.
An Enterprise Color Management (ECM) program consists of the people, products, processes and procedures to effectively manage color throughout your enterprise and extended enterprise – including supply chain, worldwide facilities, subsidiaries and business partners. Your spectrophotometer and those of your supplier and partner network are integral to an ECM program. Without accurate, reliable color measurement, ECM is moot. So what are the key considerations for selecting the right instrument for enterprise color management?
Instrument Basics
Spectrophotometers are available in handheld, compact benchtop and benchtop sizes. The size, once indicative of precision and additional features, has now become a matter of user preference and application requirements. However if your application requires the measurement of transparent/translucent films, liquids, etc., you’ll require a transmission measurement capability mainly found on benchtop and some compact benchtop instruments, such as the Color i 5. Otherwise a good rule of thumb is benchtop in the laboratory and portable on production. But make sure your software application will allow you to import/export stored color standards between your portable and benchtop systems.
Gaining Added Flexibility from Your Instrument
Consider today’s samples and tomorrow’s possibilities and make certain your system can adapt to your changing needs. Many systems offer multiple areas of view and special sample holders that allow added flexibility. In plastics applications, for example, it’s not uncommon to measure flat, opaque step chips, as well as transparent or translucent samples. Accurately measuring transparency requires a separate measurement port which, in some cases, means buying a completely new instrument. With a little up front planning, you can obtain an instrument that already includes these features, such as the Color i 5, or at least offers them as an option.
Sample presentation can be a significant source of measurement inaccuracy. Having the proper sample devices can eliminate measurement errors and offer more convenience. For example, the largest aperture opening provides the best representation of the sample. However, it’s not always practical to use the larger aperture. In fact, specifiers will often provide a sample that is unusually small such as a fabric swatch. To obtain an accurate measurement, you may need to fold the swatch several times to give it opacity. In doing so, the sample size becomes too small for the measurement port. That’s where small area view (SAV) and very small area of view (VSAV) aperture plates come in handy.
And remember to check your computer’s data interface. Although USB is the preferred choice, many systems still use RS232. Look for a system that will accommodate both interfaces.
Reference Grade Spectros
Depending on your role within the supply chain, you may require a reference grade instrument usually only available in a benchtop style. The reference grade instrument, such as a Color-Eye® 7000A, is considered by many to be the ultimate precision instrument and specified throughout supply chains by many global manufacturers.
If it sounds like overkill, it’s not. Consider the compounded effects of measurement variations as they ripple through the supply chain. By the time the product reaches final approval, a relatively small delta E color difference can resonate to triple or even quadruple the original tolerance. And that usually ends up as scrap or reclaim, if it can be salvaged at all.
In reality, most manufacturers are working with a supply chain with already established equipment. So how do you maintain measurement accuracy within a network of disparate instruments?
Measurement Integrity
Sounds like the answer is to standardize your supply chain on a premium reference grade instrument. While that seems like the best method, unfortunately, it’s not practical or plausible. Even the same high precision instruments can vary with environmental conditions. And your instrument is only as good as its last certification. So even if you certify the performance of your instrument annually as recommended, what happens in the 11 months before your next certification and factory calibration can result in measurement drift.
A new breakthrough technology, NetProfiler™, promises an industry-first, universal color measurement standard. This Internet-based application lets you remotely monitor, calibrate, adjust and certify a network of spectrophotometers of different makes and models. All instruments are calibrated to a virtual reference standard, eliminating measurement variability and making ECM a practical, viable program. NetProfiler works with GretagMacbeth and most other popular spectrophotometer brands. All that’s needed is an annual subscription and calibration standards. Though prices vary depending on the instrument, most licenses cost the same as or less than a service call. But unlike a service call, you can calibrate and certify your instrument as often as you like during your year’s subscription without incurring additional costs.
New Trends in Instrument Data Compatibility
Many companies have extensive color files that may have been established years ago using 20 nm measurement data, which was state-of-the-art back then. Today’s higher precision instruments measure in 10 nm increments Newer instruments, such as the Color i 5, now include two built-in data profiles that let you select 10 nm or 20 nm data compatibility for seamless integration within your instrument network. Expect to see more profiling capability and Internet based applications and services for instrumental color measurement – especially as Enterprise Color Management (ECM) reaches critical mass.
To search for vendors of color measurement and management systems, search our buyer's guide database.