Over the years, we have been asked, on numerous occasions, to provide evidence based results to assist in disputes between customer and supplier over the acceptability of a colour match. Although each dispute is unique, they all have a common theme which can be summarised thus:
The reason why such disputes occur can be explained by taking the example of the Blue 109 Standard which is one of the 140 colours supplied by the British Standards Institution in the form of the BS 381 collection of standard colours. Blue 109 comes in the form of a coloured card which is intended to be used as a visual or instrumental reference for colour matching purposes. There are, however, no instructions associated with this standard or with the BS 381 collection as to how good the colour match has to be.
Now consider these two specifications:-
Basically disputes like this arise because the customer uses Specification 1 and thinks it means the same as Specification 2.
In order to avoid such disputes, the customer needs to specify not only the colour but also how close the colour match to this standard should be. The difference between two colours can be measured instrumentally (using a colorimeter) and expressed in "Delta E units" where a Delta E value of zero represents a perfect match. The greater the Delta E value, the poorer the match and as a general rule a Delta E difference of 1.0 is perceivable visually while a Delta E difference of 0.2 represents the best match obtainable for commercially produced paints. In practice there are some shades where a small change in Delta E can result in a noticeable colour change. Yellows and brown shades are particularly Delta E sensitive while reds and blues can tolerate much larger Delta E changes without perceptible colour change. Greens lie somewhere in the middle.
At first sight the simplest solution to the colour specification problem, once it has been appreciated, is to specify a match to the tightest possible specification ie a Delta E value of 0.2 or less. In practice however although top quality automotive paints tend towards this value, other types of paint may not available to such a tight tolerance. It is at this point that the situation becomes quite complex for the customer because he has to consider a number of questions without being certain of how to obtain the answers or indeed how to interpret the answers once he has them.
We assist clients with a wide range of colour specification problems and some idea of the complexity of the subject can be illustrated by considering the example of the type of questions that an architect might pose when specifying doors, windows and other building components:-
It can be seen from these questions that colour specification is far from straightforward. Getting it right is not easy and getting it wrong can be very expensive.
Our consultants can act as advisors, arbitrators and expert witnesses. They can also work with you during the early stages of a project and help you to specify exactly what you need.
PRA Irfab have released the first module of the new Global Industrial Coatings Market study, Protective.Read more
Did you miss PRA’s 10th International Woodcoatings Congress? You can now buy a copy of the full proceedings and papers from the European Coatings Website!Read more
We will be closed between Saturday 24th December 2016 and Monday 2nd January 2017.Read more
Notice of Management Buyout of PRA from Pera Technology SolutionsRead more
Welcome to our newest member - Olin Epoxy!Read more
PRA are pleased to welcome M&K Ghana to membership.Read more
PRA is delighted to welcome another new member to the PRA - Dupre MineralsRead more
The market for agricultural, construction and earthmoving equipment remains attractive, according to a recent artic… https://t.co/O5QFztHagi
Our Principles of Waterborne Technology course is a hit. Simon Palm of Kriya Materials said: 'The course is packed… https://t.co/1rGSiDUI2p
On November 15, PRA will be making their way to Mottram Hall in Cheshire to attend the BCF Awards. We’re delighted… https://t.co/UbNR63C20N
PRA’s Paint Technology Course is getting great feedback. Peter Carter of Camcoat Performance Coatings said 'Excelle… https://t.co/DgADM6vHqz
Congratulations to Miriam Peralta from Lubrizol, winner of the Holbrow Medal for Best Paper presented at PRA’s 11th… https://t.co/3D49HaeSbv