Visual and instrumental color matching: How do they work together?

Visual and instrumental color matching: How do they work together?

The human eye is incredibly effective at discerning different colors, and different shades of the same color. Research estimates that humans can distinguish up to 10 million colors and shades.
That is why vision still plays an important and irreplaceable role in color matching, as there is no substitute for a trained color expert with a keen eye. However, because there are many contributing factors in a color match, it can be a lengthy process to obtain the best match for a customer, which is where instrumental color matching comes in.
In the industrial colorants industry, human vision and technology work together to provide paint and coatings companies with the most accurate color matching for their products.
Here is how man and machine work together to deliver the best color match.

Instrumental color matching
To match colors using an instrument, you need a spectrophotometer and a software program capable of analyzing how a colorant absorbs and reflects light. The spectrophotometer and software are sensitive enough to detect subtle differences in how the colorant in a given material reflects light, far more perceptible for quantifying what is contributing to those differences than those detected by the human eye.
This is important, because light can behave differently depending on the materials used in a coating film, which can alter how the viewer perceives color. 
With instrumental color matching, software assigns a mathematical value to the color it detects, giving chemists a quick-reference way to evaluate potential formulas using different pigment chemistry. The software can also be programmed to factor in metamerism, cost, end-use properties and resistance requirements specified, helping color chemists devise industrial color formulas that are ideal for each customer.
Just as important, color-matching software can alert chemists when a targeted color match is not possible. If a target color is not fully achievable because it is outside the color palette in use for a particular coatings product, the system can readily identify it. This capability can save chemists and their customers significant time in pursuit of an impossible color match and allow them to find alternative solutions together.
It is critical to remember that the system will provide a color match based upon its settings, which include but not limited to, instrument geometry, degree observer, color space and illuminants. When the system has a match by instrument measurement, it may or may not look like a match visually; that will depend upon how closely the settings will simulate how the eye sees it.

Visual color matching
In short, instrumental color matching can detect very subtle color shifts, examine multiple colorant combinations, take outside factors into account and identify impossible matches, all in a fraction of the time it would take a person to do the same.
However, there are numerous color variations and conditions that could be involved. As a result, it could take extensive research, equipment and setup to meet every need that might be encountered for a color match, so the resulting color from the formulation system may not always correlate visually.  That’s why the trained eye still plays a very important role in color matching, not only for these situations, but also for the skill needed to use the spectrophotometer and software tool in the most effective way. Using equipment and settings that reflect the majority of the daily work is recommended.
The most common instrument setup used in the coating industry contacts the color target at one angle of measure and has sphere geometry with the specular included. This setup performs well as long as the sample surface being analyzed is smooth and consistent and is similar in sheen to the coating being used. But instruments can encounter problems with this setup when there are textured samples involved or there are differences in the surface between the target sample and the coating being used. These differences can alter the amount of light absorbed or reflected, which can cause instruments to detect a variation in color that isn’t there, or fail to detect one that is.
Effective color matching is a system of checks and balances between man and machine. Technology allows chemists to build data that can produce an accurate color match, as well as to assess and communicate differences in color.. But it’s never a good idea to rely solely on instruments to perform your industrial color match. Color samples always need the watchful eye of a trained expert, overseeing the entire color matching process from start to finish.

How can you use visual and instrumental color matching to attain perfect color matches for your customers? Contact Chromaflo at (440) 997-5137 to discover the keys to effective color matching.

Author: Teri Kummer, Color Science Manager - Americas
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