Featured Product
This Week in Quality Digest Live
Metrology Features
Andrei Vakulenko
3D scanning speeds custom product design
Ryan E. Day
FARO products help Composiflex deliver industry-leading service
DP Technology
Seamlessly integrates with milling center, enabling company to make full use of five-axis machining capabilities
Dat Duthinh
Were secret emergency repairs for New York’s Citicorp Building in the late 1970s actually unnecessary?
ZEISS Industrial Quality Solutions
German precision and powerful centrifugal force

More Features

Metrology News
Stereotactic robot helps identify target and deliver electrodes to target with submillimetric accuracy
GOM CT scanner offers highest accuracy and resolution of any 225kV system available today
Instantly separates surface texture into wavelength bands, displays data in highly intuitive, single-screen interface
Delivers production calibration and color profiling capabilities for the widest range of industrial print applications
Provides eight operating modes and five alarms
The profile measurement system has an accuracy of 5 µm and a measuring range of 1 mm to 50 mm diameter
ATOS Triple Scan used to design 12 bronze busts
Kreon breaks new ground with 3D scanner designed mainly for CMM applications
Deal provides new and better solutions for customers

More News

Tim Mouw

Metrology

Five Steps to a Successful Color Quality Control Program

Setting up a color QC program can help you accurately communicate color with clients and suppliers

Published: Wednesday, July 24, 2019 - 12:03

Spending too much time and money on incorrect color? Even if you use the best color measurement tools available, your color will still fail without quality control. You may think you’re doing everything right, but if you (or worse, your customers) are rejecting a lot of products, then there’s more you should know.

Quality control (QC) means verifying the color you specify is the same color you manufacture, throughout production. Setting up a color QC program can help you accurately communicate color with clients and suppliers, inspect raw materials before you begin working, and verify that your color is correct before you ship.

Whether you have a quality control program or are considering one, here are five important components to consider with regards to color.

1. Quantify color using a spectrophotometer

Human vision is subjective, which leads to communication errors and confusion. A little brighter, a touch bluer, or a smidge darker are impossible to achieve without hours of trial and error. Measuring color with an instrument such as a spectrophotometer instead of just evaluating by eye can dramatically reduce that wasted time.

A spectrophotometer captures and evaluates color by filtering light into very narrow bands of color, which pass back up through the instrument’s optics and into a receiver to be analyzed. The spectral reflectance curve provided by a spectrophotometer is commonly known as the color’s “fingerprint” because it is unique to that color. Comparing spectral data is the most accurate way to quantify color.

When it comes to spectrophotometers, there are three primary types: 0º/45º, sphere, and multiangle. They come in a range of sizes, from portable devices to large benchtop instruments. Selecting the right spectrophotometer depends on application, desired functionality, and portability.

 

Macintosh HD:Users:nicolespoonster:Downloads:Ci6x_in_use_02-2.jpg

2. Choose an acceptable color tolerance

A tolerance is the amount of acceptable difference between the color you hope to achieve (called the target or standard) and the color you produce (the sample). The size of the tolerance you choose is important. If your tolerance is too tight, you’ll spend a lot of time trying to hit an unachievable target. But if your tolerance is too large, you’ll approve colors that your customer will reject.

Not sure what tolerance method to use? Read my earlier article on color space vs. color tolerance.

Macintosh HD:Users:nicolespoonster:Downloads:tolerancing-key-to-accurate-color-white-paper-400x285-grid-4.jpg

3. Analyze color using QC software

QC software can help you compare production color against standards, using tolerances to determine pass/fail status. the software can notify you if the color starts to drift, and help you figure out what you need to do to bring it back into tolerance. QC software can also track trends to generate historical reports, which is especially helpful when you’re working with a global supply chain because it keeps everyone informed and accountable.

4. Visually evaluate color by eye

Visually comparing the color you produce against the target color is the first line of color evaluation. Although this may be sufficient for less stringent color applications, it also leaves the door open for error and disagreement with your customers and suppliers. That’s because many people are not properly trained to visually evaluate color, different lighting conditions can lead to variable assessments, and everyone sees color differently.

In fact, one in every 13 men and one in every 300 women exhibit some type of color deficiency. Everyone who is involved in visual evaluation should take—and pass—the Farnsworth Munsell 100 Hue Test, because a quality control person with subpar color vision will make bad decisions.

To find out if your color vision passes the test, check out this online color and hue challenge. (It’s fun, but not a substitute for the real FM 100 Hue Test.)

Macintosh HD:Users:nicolespoonster:Desktop:Screen Shot 2019-06-24 at 3.46.55 PM.png

5. Evaluate color under controlled lighting

Viewing a sample’s color in the parking lot is not considered standard D65 lighting. Natural daylight is dynamic. To have it agree with standard lighting, you can evaluate outside only between 11 a.m. and 2 p.m. using North Sky Daylight. But what if it’s a cloudy day? And what does the third shift do?

The best way to know how your assembled products will look once they enter the world is to use controlled lighting in a light booth. The benefit of calibrated light booths is that they come with light sources that agree with CIE standard illuminant values, which are used for calculating colorimetrics in QC software. When everything agrees, you can make confident color decisions.

Macintosh HD:Users:nicolespoonster:Desktop:Screen Shot 2019-06-24 at 3.45.37 PM.png

Discuss

About The Author

Tim Mouw’s picture

Tim Mouw

Tim Mouw is the manager of applications engineering and technical support for X-Rite Pantone in the Americas. Mouw oversees a team of 20 technical support specialists that help customers manage and improve color quality control processes. Mouw has taught more than 300 color science courses throughout North and South America, Europe, Asia, and Australia. X-Rite helps customers communicate and manage color standards for raw materials, paper-based products, ink, photography, video, metal, glass, textiles, plastics and wood.

Comments

Color Quality Control

While color is not a physical property, it is an important attribute for many products.  A visual tolerance for allowable variation needs to be established based upon expert evaluation under controlled environmental conditions as well as in a "natural" setting of where the color will be viewed by the customer.  Then, a correlation can be mapped to a given analytical device that applies a numerical value to color.  For a company that has yet to select an instrument to measure color, one must be extremely thoughtful to understand how the instrument receives a signal as well as how that signal is conditioned to provide you a number or a set of numbers to judge the quality and consistency of this attribute.  

 

In my opinion, the 5 items listed in the article are important, but may need to be re ordered to ensure success.

Douglas - I appreciate your

Douglas - I appreciate your comments, and you make several good points.  Specifcally, selecting the right type/geometry of instrument is a critical choice.  While a single angle instrument (0°:45° or 45°:0°) is the right choice for some applications, a spherical device (d/8°) or a mutli-angle device may be the better choice.  All of this is dependant on the material being measure, just as you menitoned.  Investing in the work to determine the proper type of device for measuring color of a specific material is critical to success.