An Objective View on Colour Fastness Grading
This article was written by Phil Patterson, MD of Colour Connections and Editor of the Textile Dyer, the new on-line magazine dedicated to the textile dyeing and finishing industry.
DigiEye provides an objective view on colour fastness grading
Whenever the economic outlook gets gloomier it becomes more important for all parts of a textile supply chain to work together more closely to reduce duplication of effort, reduce unnecessary testing costs and to increase levels of trust, thus enabling more efficient working.
Unfortunately this is often not the case and customers and suppliers are driven apart as they try to squeeze a bit more profit for their own organisation. Nowhere is this more apparent than in the interpretation on test results with sellers grading test results leniently and buyers judging them harshly.
The past decade has seen massive improvements in the consistency of the colour fastness testing methods but with a disappointing downward trend in the accuracy and integrity of grading of those tests.
There is also a fear by some independent labs that they will be held responsible by brands if merchandise with a ‘pass’ certificate results in customer complaints- and this fear leads to harsh grading as individuals and companies strive to cover their backsides.
With my textile consultant’s hat on I’m often asked by clients what they should do when faced with a borderline fail on a fastness test. Much as I would like to propose a technical solution to improve the product, my standard answer is to advise them to get the physical test pieces submitted and get them graded with DigiEye.
What is DigiEye?
It is a digital camera used as a colour measuring device, in a specifically designed light box with controlled lighting linked up to some clever software.
In short it is what the industry has needed for years and what buyers, sellers and everybody in industry should be using for grading colour fastness.
Imagine if you received a fine and driving ban because a policeman thought you’d been driving a bit too quickly as he saw you pass.
Well how absurd that multi-million dollar decisions are made based on human vision, with all its known limitations and flaws, when the technology exists to give accurate, objective measurements.
DigiEye is actually capable of a lot more than colour fastness grading, (as we’ll see in future articles), because it is essentially a non-contact colour measuring device that can measure anything that fits in the box – and if things don’t fit in the box the box a larger version is available.
Colour fastness tests are measured (the digital camera is surprisingly accurate and not too far behind good quality spectrophotometers in terms of accuracy and reproducibility) and a clever algorithm converts the measurements into the grey scale measurements used in colour fastness grading.
Because it is a non-contact method the machine and software is capable of measuring several tests simultaneously (such as all the fibres on a multi-fibre strip), which is a massive improvement on early methods using spectrophotometers that could only measure one test at a time.
And because the measurements are real, rather than estimates, the software can provide results to two decimal places rather than rounding down figures to the nearest half point.
This enables buyers and technologists to make much better judgments on borderline merchandise:-
a. Because the results are more accurate.
b. Because results of, say, 4.49 stay at 4.49 rather than being rounded down to 4.
The previous point is important because, in addition to catching the cheats who are putting sub-standard merchandise into the system, it also stops the unnecessary rejection of harshly graded merchandise which is good for retailers, the industry and the environment.
So far a number of retailers, including Marks and Spencer, have recommended the use of DigiEye for grading of fastness results and a number of independent laboratory groups such as ITS and STR have invested in the technology to give a better service to their clients.
The DigiEye technology costs from £10,000, and in some areas of the world this would pay for a number of human graders but if the investment saves an organisation making one bad decision it could pay for itself several times over.
And if this sounds too good to be true then consider the pedigree of those behind its creation. Ronnie Luo is widely regarded as one of the top colour physicists in the world today and his mathematics are married up with the controlled lighting expertise of Verivide to deliver one of the ground breaking inventions of the past decade.
Dyers who are providing honest results from good graders should also look at the mathematics and business benefits – all visually graded results are rounded down and this varies from 0.01 to 0.49 points with an average of 0.25 points.
The use of DigiEye makes you on average 0.25 points better overnight, and with some retailers now giving concessions for DigiEye graded samples it makes sound sense to embrace the best available technology.
Phil Patterson
June 2008
PHIL PATTERSON
Phil Patterson, Managing Director of Colour Connections, has wide ranging expertise in the textile industry gained from a career that has spanned research, manufacturing and retail; fibres, fabrics and garments; legislation, environmental compliance, standardization and innovation.
Recognised as an expert solutions provider to those trying to meet the most demanding technical and compliance standards he has vast experience in delivering policy, standards, innovation and technical support throughout the textile supply chain.
A respected authority in the textile and coloration industry, and increasingly a source of common sense for journalists, editors and authors, he has a rare enthusiasm and drive for improving textile products, processes and knowledge coupled with an ability to present solutions and advice in easy to understand language.
Phil is also the editor of Textile Dyer, the on-line magazine dedicated to the textile dyeing and finishing industry.