Color QC and Matching Blog

Spot On: Lessons from a Color-Matching Master

As the North American Manager of Color Services for Pittsburgh-based PPG, a $16 billion per year manufacturer of paints, coatings, chemicals, optical and glass, Shelley Sturdevant knows something about color matching. She manages and oversees color control for the Coil and Extrusion coatings business at 10 facilities nationwide, with a color palette currently holding over 100,000 colors.

We had the opportunity to spend a few minutes with Shelley as she shared some of what she's learned managing color for PPG over the years:

CyberChrome (CC): What prompted your move into digital color matching and when?

Shelley Sturdevant (SS): About 10 years ago we decided we needed to find the right tools, the right hardware and software, to manage our color needs then and into the future. We needed to build a foundation to manage our huge color palette, including some colors we've been managing for more than 30 years.  That's when we settled on OnColor.

CC: What were you looking for in a color matching software application?

SS: Two things primarily, speed and productivity. The OnColor software can search through 50,000 to 60,000 colors in seconds. And, uniquely, it gives you the ability to do very specific color calibrations. It's an important tool for us in the lab but it's also key to our production in batch correction so technicians at all 10 of our facilities can consistently produce the same colors.

CC:  Anything else?

SS: Compatibility with a range of spectrophotometers. That enables us to get the best hardware to pair with the software. These tools form the foundation of our house so to speak, but where it really gets interesting and valuable is what you might call the ‘attached garage,' that is, how we use it to interface with our customers.

Now, we're all speaking the same language, not just internally, but we can communicate that directly to our customers. About 40 percent to 50 percent of our customer base has adopted our software and hardware systems models and we train them how best to use it. We can all access the same database which we put up on the Web and they can see new colors, research standard colors, and get precise, reproducible results.

CC: What are some of your newest challenges?

SS: Working to comply with the new ‘green' regulations that have recently been enacted, specifically achieving maximum solar reflectance values (SRVs) without sacrificing the quality of the color match. 

These new formulations take the known color matching rules and throw them out the door.  The use of brown (blended) pigments to effect L value (versus traditional black pigments) creates new color matching models and obstacles.  So, we have to rethink how we match colors.

CC: Thank you for spending time with us.

SS: Thank you.

10 Surefire Ways to Improve Your Color Matching Results

Paying attention to details can help you get the most out of your investment in a color matching system, get you the best color match accuracy, and get your colors approved in the fewest hits.

1. It's all about the database.  Or what's under the hood? Color matching starts and ends with your color matching database. How good is it? How old is it? Just a few years out-of-date is a lifetime in technology improvements; five or more years borders on Paleolithic.
2. Sampling sense. Were your samples prepared in a manner consistent with how you actually manufacture your product? Are the raw materials  (colorants, bases, resins, substrates) you use today the same as you used when the database was prepared?
3. Reliable replication. Good science and good business practice require that results be replicable, easily and consistently. Will a sample made by your lab technician today match your original used in the database?  When preparing a new database, use your most skilled technician.  Temporary employees are barely a good idea at your reception desk, let alone a temp managing your colorant database.  Tighten up procedures and your color matching accuracy will tighten up too.
4. Trust everyone but cut the cards. Check your incoming raw materials, especially the colorants, for shade and strength. Don't assume they are always 100 percent strength and exactly the correct shade.
5. Standardize. Use standardized lots of colorants when you make samples. Get a COA from your supplier and note which lots were used to prepare the database.
6. Duh! Not quite as fundamental as, "Is it plugged in?" but be sure your database is properly loaded. You'll never get the right results with a database incorrectly loaded.  Look for negative data and wayward levels on the colorant build curve.  
7.  Optimize, then verify. Optimize the database and validate it using known samples. Repeat the process of validating the database using known mixtures at least once a year.
8. Know what you know... and what you don't know. Be sure you truly understand how to run your software. More important, be sure you know how to interpret the results and pick the best match for the task at hand. 
9. Think first, select second. Consider how the colorant combination will work in production before automatically selecting the "Best Match." Getting a practical, workable formulation up front makes production adjustments easier and causes fewer difficulties later. 
10. Apples to apples. Make sure your database was measured on the same instrument you are using. Differences between instruments will directly result in less accuracy in your matches and corrections. Using a "canned" database can seem like a good idea because it saves time and lab resources and pushes the responsibility onto someone else. However, if your measurements, procedures, and raw materials don't exactly duplicate those used to prepare the database, you may be very disappointed in your matches.

Are you happy with the way your colorant database is matching?

Color Geometry: A Matter of Degrees

Long before computers were invented a radio, film, and television comedy team known as Abbott and Costello perfected a classic skit that became known as the "Who's on First?" routine; essentially a dizzying five-minute display detailing by example the pitfalls of miscommunication via homophones, homonyms, home-run hitters, and high comedic art.

Not so funny is the frustration and confusion many working in color measurement experience due to the persistent misuse of terminology. "Why don't my color numbers match?" is a question we hear often.

The Many Angles of Color Measurement

Probably the most common misconception is about the 2° and the 10° observer.  This frequently gets mixed up with the geometry of the measuring instrument with users saying they measured the color at 10° using D65 illumination, when in fact what they measured the sample with was a 45° /0°  instrument using tungsten illumination. The 10° comes into play with the Standard Observer they chose for the tristimulus weighting functions.

There are two areas where these angles come into play and it's easy to see how they can become confused:

The first is the instrument geometry and how the light source and detector are positioned relative to the sample.

• The second is less obvious and goes back to how the tristimulus weighting functions are specified.

The 45°/0° refers to the geometry or optical design of the measuring instrument, be it a colorimeter or a spectrophotometer.

The most common instrument geometries used today are either 45°/0° or d/8°.

The instrument geometry is described by a pair of angles or letters. The first letter or number in the pair is for the angle of illumination; the second is for the viewing angle (or the angle that the light is detected).

 

So, for 45°/0°, the sample is illuminated at 45° off the normal (perpendicular to the sample) and the reflected light is viewed or detected at 0° (meaning perpendicular to the sample). 

In the second example of d/8°, the ‘d' stands for diffuse illumination, meaning the sample is illuminated at all angles by diffuse light coming from the integrating sphere. (The integrating sphere is the white-coated ball collecting and diffusing the light).

The second term in d/8° stands for the angle of viewing which is 8° off the normal.

 

 

 

Angling for better color management

So, what are the 10° and the 2° all about?

This seems to be where all the confusion is centered. These angles refer to the Standard Observer and have nothing to do with the geometry of the instrument or the angle at which the samples are viewed.

Instead, the 10° and the 2° angles refer to the field of view when physically viewing a sample. The field of view subtends either a 2° or a 10° angle on the retina.

A better way to understand this is that a 2° field of view is equivalent to viewing a 1.7cm circle at a distance of 50cm; a 10° field of view is equivalent to viewing an 8.8cm circle at a distance of 50cm.

So roughly, the 2° field of view is equivalent to viewing a 1.7cm circle at a distance of 50cm; or like looking at your thumbnail at arms length away and the 10° field of view is like looking at the palm of your hand (or a three-inch circle) at arms' length.

The color of consistency

In industrial color control, the 10° Standard Observer is recommended because it more closely approximates the size of samples being evaluated, but you'll still find lots of standards and procedures using the 2° Observer.

These terms are important when trying to communicate color up and down the supply chain. Being able to communicate precisely how the numbers were determined is key to someone else being able to reproduce them accurately.

And now, if someday you're out at the ballpark and someone asks you, "Who's on first?" you'll know to just tell them, "Yes," and let it go at that.

Color Me Stressed Out

If we put you under the spectrophotometer now, would you show up in deep shades of recession blue? Perhaps.

Tough economic times often mean having to make do with fewer resources to handle the workload. The same workload for developing new colors, adjusting production batches, and approving colors is spread over fewer people. Staff become stressed and can easily overlook color shifts they might otherwise have caught.

And, as you know, color shifts take time to correct. They result in product that either has to be reprocessed or worse, discarded, let alone the time and labor required to make the corrections.

Sometimes, it's the more experienced staff-the more expensive staff-that had to be let go, and along with them, went years of knowledge of how to work the color matching system or operate older, more finicky equipment.

But, just like a painter who switches from brush to roller and roller to spray gun, an investment in the right industrial color matching or color quality control technology can help ease the burden while increasing productivity and reducing costs.

Don't paint yourself into a corner

Investing in technology is one way to keep up with demand while keeping payrolls lean. 

Consider these advantages from a new, up-to-date, industrial color matching system:

Fewer production adjustments: The software can automatically calculate and add colorant to bring production back on track.

• Optimized adds: Color matching software can find the one, optimal colorant to add to correct a batch.
• Batch size variation adjustments: Color quality control software automatically calculates accurate adjustments by weight or volume, or even when the batch amounts are not known.
• Faster estimating: Detailed production costing lets you provide estimates faster, beating the competition to the bid.
• Wider color range: Today's sophisticated industrial color matching software databases help you reduce the number of colorants in inventory while broadening the range of colors you can produce.

This recession will end someday (or so they keep telling us). In the meantime, consider how technology can increase productivity, lower inventory, and keep staffing costs in check. Then, focus on the future, one with a bright, sunny, yellow outlook.

Report on the 11th AIC Colour Congress 2009 Sydney

The 11^th Congress of the AIC (International Colour Association) was held at the John Niland Scientia Centre, University of New South Wales in Sydney at the beginning of the month and was a highly successful event.

There were over 330 delegates of whom ~220 were from overseas in fact from 34 countries from most continents around the world.

The Congress showcased the latest research and development in all disciplines of colour study from architecture to design, measurement, psychology, philosophy, science and vision with the participation of leading international researchers. Over 130 oral papers and 80 poster papers were presented during the Congress.

The Opening Ceremony had a very strong Aboriginal component with a traditional Welcome to Country; which was very moving. Delegates also had the opportunity of being involved in a sand painting created by local artist Walangari Karntawarra.

 

 

A dynamic and colourful keynote address titled ‘Why are animals colourful? Sex and violence, seeing and signals was then presented by Professor Justin Marshall from the Sensory Neural Group, School of Biomedical Sciences and Queensland Brain Institute, The University of Queensland.

New features during and prior to the Congress were:

1. Pre-conference workshops

Master Class for Artists and Designers - Associate Professor Lois Swirnoff

Colour: Meaning and Communication - Associate Professor Dianne Smith

Introduction to Colour Psychology and Statistics - Professor Byron Mikellides

2. Overview sessions on the latest in research in:

          Colour Vision - Professor Paul Martin

          Colour Science - Professor Roy Berns

          Environmental Colour - Associate Professor Karin Fridell Anter

3. Two multi-disciplinary Symposia

          i. Appearance in Nature and Design

          Speakers:      Dr. Kevin Hellestrand - Underwater photographer and Cardiologist

Chalisa Morrison - Senior Design Colour and trim Toyota Design Australia

Gabi-Kigle-Boeckler Global Business Manager with BYK Gardner GmbH

            ii. ‘Good' and ‘Bad' Colours: Painting, Conservation and reproduction

          Speakers:      Dr John Gage - Fellow of the British Academy

Dr. Maria Kubik - Paintings Conservator Art Gallery of Western Australia

Professor Roy Berns - Richard S. Hunter Professor in Color Science, Appearance and Technology, Rochester Institute of Technology, USA

The seminars successfully met their objective of encouraging inter-disciplinary discussion and interaction.

There were over 20 papers relating to colour measurement and one session devoted to colour control in the automotive industry in addition to the Symposium on appearance.

The social functions included dinner on a Sydney Harbour Cruise and an excursion combining the Sydney Botanical Gardens and the Aboriginal Art Exhibition at the Art Gallery of New South Wales.

Copies of the Proceedings on CD are available for purchase at a cost of A$175.00 plus postage.  To purchase, please email: sales@nhpl.com.au .   Please note stocks are limited.

The 12^th Congress in 2013 will be held in Gateshead, England with interim and mid-term meetings:

2010: Argentina - Colour and Food - From the Farm to the Table

2011: Switzerland: - Interaction of Colour and Light

2012: To be confirmed

CyberChrome was a Congress sponsor.  Comments from any attendees are welcomed.  This blog post was written by the Conference Chairman, Nick Harkness of NHPL.  http://www.nhplcolour.com/ and nick@nhpl.com.au

 

Installing OnColor Color Software under Windows 7 and Vista

The OnColor  Suite of color QC and color matching software is licensed through use of a hardlock key.  The USB hardlock key that is shipped with the software can be used on one computer at a time. 

There are two ways to successfully install the Hardlock driver required for the USB key used by OnColor in Windows 7 and Vista:

1. OnColor setup will run HLDRV32.EXE (Included on the installation CD) which installs the Hardlock drivers.
2. Allowing Windows to install the Hardlock driver the first time the USB key is used.

If both driver setups take place, however, the Hardlock key will not work as the drivers conflict.

The preferred method is to follow our instructions and not insert the Hardlock USB key until after the setup of OnColor.  The OnColor setup will run HLDRV32.EXE, which will prevent the Windows drivers from being installed when the USB key is inserted.

If for whatever reason, the Windows driver for Hardlock has been installed before the OnColor setup, you must uninstall the HLDRV32 Hardlock drivers after the OnColor setup.  To uninstall the Hardlock drivers, go to the Control Panel -- Programs and Features, which shows a list of programs that can be uninstalled.  You should see "Hardlock Device Drivers" in that list.  Uninstall that program.  Unplug the Hardlock key and then reboot the computer.  Plug in the Hardlock key and you will now be using the Windows supplied Hardlock driver.

If you know that the Vista Hardlock key driver has already been installed by Windows, you can hit the Cancel button during installation of the OnColor CD when the Hardlock setup dialog is displayed and then continue on with the OnColor installation.

Color Matching of Plastics and Coatings

The latest newsletter of the Color and Appearance Division of the Society of Plastics Engineers contained a noteworthy article that should be read by anyone involved in the coloring of plastics or coatings.  Bruce Mulholland of Ticona authors a technical article "Effect of Additives on the Color & Appearance of Plastics".  It can be found in the SPE CADNEWS Summer2009 starting on page 14 at:

http://www.4spe.org/technical-groups/newsletters/105

His opening salvo was right on target about how often color is just considered a necessary evil in the product development cycle.  His 9 steps of a typical cycle made me laugh, but sadly are all too often true.  The article goes on to describe in depth why color cannot be an afterthought in the development cycle. 

What I particularly liked was his explanation of the physics of light scattering and absorption and how various additives to a resin system will affect the color.  Equations and diagrams are used to explain how changes in the refractive index within the polymer system will change the color.  He describes the effects on color in different resin classifications and then goes on to list typical additives and how they affect light scattering and therefore the color.  Any color chemist who wants to understand more about these interactions with light and color would benefit from reading this article.  This article would also be of interest to anyone involved in the coloring of plastics-from designer and specifier to the development chemist and technician.  Even their counterparts in the coatings industry would benefit from understanding the principles described here.

While you may not always like what happens to a color formulation when you put it into a product matrix, at least now you can better understand what's going on and why.

Connecting your color spectrophotometer to OnColor with a USB adapter

Many color instruments and spectrophotometers in use today come with a serial cable to connect and communicate with a computer.  However, serial ports are a thing of the past and very few PC's come with a serial port as standard configuration these days.  While you can always install a serial port, an easier way to connect to the PC is to use a Serial to USB adapter.  This is a special cable that plugs into the serial port output of your spectrophotometer on one end and plugs into a USB port on the computer on the other.  This circumvents the need for a serial port on the PC. 

There are a few tricks to getting this to work however.   Resist the temptation to just plug the cable in and see if it works!!!    First, it is important that you read and follow the installation instructions that come with the USB adapter.  Typically (but not always), the instructions will direct you install a driver for the adapter BEFORE plugging it into the computer.  It's important that you follow the proper sequence, because once you get Windows confused on what is attached to this port, it can be difficult to undo it.

After installing the driver, go to the Windows Device Manager and go to Ports and note what COMM PORT the adapter was assigned to. I In Windows Xp Device Manager is found under Control Panel, then System, then Hardware tab, and then Device Manager button.) You will need to know this in OnColor when you tell it what Comm. Port to look for the spectro on.  Then connect the spectrophotometer to the adapter and finally plug it into the PC.   

For spectrophotometers that do not use a "straight through" cable, you will need to use the manufacturer's cable out of the spectro and then attach the USB adapter to the 9-pin end of that cable.  (Examples of spectros like this would include the Konica Minolta CM-3600d, CM-2600/2500d and CM-3700d.)  

Finally, you can open OnColor and go to Communications, choose the comm. Port assigned to this adapter and then test the settings.  You should be good to go.

Don't move the adapter around to different USB ports, as the driver typically only configures it for that one USB port.  If you move it to another USB port, it may be assigned to a different comm. Port number. 

Not all USB adapters are created equal.  Some are not compatible with Windows Vista.  Others don't handle this type of data communication well.  We recommend the Belkin serial to USB adapter (http://belkin.com/support/product/?lid=en&pid=F5U257&scid=1 )  since many OnColor users report no problems using this model.

How to improve Inter-instrument Agreement with Instrument Profiling

So many color disputes arise these days because color instruments don't necessarily read the same.  Electronic color standards are widely used and shared within a supply chain and have many benefits, but if all of your instruments are not regularly monitored and are known to read the same, then problems can arise. 

Many users assume that since they do a daily calibration on their instrument, their readings are correct.  And if they are correct, then they must match every else's.  That's not usually the case.  Spectrophotometers from different suppliers may read color differently.  Even with the same model from the same supplier, significant differences can be found depending on the age of the instrument and how well it is maintained.

In order for electronic standards to "work" within your supply chain, you need to be able to recall a stored standard, measure the actual stored standard on another instrument and have a resulting DE of 0.15 or less.  The number of 0.15 is dependent on how tight your tolerances are.  If you are trying to supply a color match that is < 0.5 DE, then you certainly don't want to have half of that deviation taken up by lack of inter-instrument agreement.  A good rule of thumb is that no more than 25% of your tolerance should be given up to instrument variables (such as INTER-INSTRUMENT AGREEMENT, sample repeatability, and instrument repeatability).  So if your tolerance is DE=1.0, then you can live with measurement uncertainty of up to 0.25 DE.    If your tolerance is DE < 0.5, then you can live with an uncertainty of no more than 0.125.  So as tolerances get tighter and supplies get more critical of color, INTER-INSTRUMENT AGREEMENT becomes more important.  Instrument profiling can help you achieve the INTER-INSTRUMENT AGREEMENT that you need in order to meet these tight tolerances.

One advancement in color technology in use today is instrument profiling.  Instrument profiling is used to make a population of spectrophotometers read to within a tighter specification of each other.  A master instrument is used as the reference point and all other instruments are "cloned" to match this master instrument.  A complex set of equations is used to profile or "correct" a target instrument so that its spectral data mimics that of the master.  After profiling, all data taken on the target instrument is now corrected to match the master.  The result is much tighter agreement between instruments which leads to fewer disputes over whether the color match is acceptable and faster acceptance and approval of submits.

Color Correction – How to use your color software to get practical answers

Have you experienced a case where the color computer wants to double the batch size and add a ton of white to correct a batch?  Or maybe it's adding some red and you think the color is already too red? A common complaint about color matching software is that it gives bad answers or impractical adds to correct the color of a batch. 

Well...this frequently happens when a minor colorant is overshot in the batch and the only way the computer knows to correct it is to dilute it out by adding all of the other colorants.  Remember, the color computer is always trying to go for the perfect match or DE=0.00.  Often times this is not the "perfect answer" in the practical world.  The colorist is frequently able to accept a small color difference if he can fix the batch with the add of one colorant, or a small add of two colorants.    In these cases, using the manual correction features of OnColor can solve the problem by giving you control with practical choices on how to adjust the color of a batch.

The Manual Add feature gives the colorist complete freedom to "fix" the batch with whatever colorants and amounts he chooses.  The colorist usually starts by setting the computer generated adds to zero for all amounts.  Looking at the color plot and  color differences, the colorist can then try different adds and see the effect on the delta components and the DE.  Using his knowledge of the colorants and products, he can interface his practical experience to get an answer that gets him to an acceptable tolerance, while still being a reasonable add.  Colorists like this feature because it puts them in control of the decision making process.

The Optimize Add feature is used to try and correct the batch with an add of only one or sometimes two colorants.  In many cases, a colorist will prefer correcting a batch by only adding one colorant.  This is due to speed and simplicity.   The Optimize Add feature allows him to select the colorant and then automatically computes the "best add" (the add that will yield the lowest DE) of this colorant.  If needed, he has the option to optimize on another colorant if it is needed to get within tolerance.  The benefit of this feature is that the batch may be adjusted to an acceptable DE with a small add of only one or sometimes two colorants.  The fewer colorants to be added, the less chance there is of making a mistake or mis-weighing a colorant.

The Reduce Add feature uses a special algorithm to reduce the size of the add by accepting a DE greater than 0.0.  The user inputs the DE or tolerance that he can accept, and then the color matching software computes the smallest add that will get within this tolerance.

Using these manual adjustment routines can greatly speed the batch adjustment process.  They save time and money by making smaller adds than the automatic add, while allowing the operator to blend his practical experience with the sophisticated algorithms of the color computer.