Why is controlling colour complicated?
Six key factors for an appropriate production process
Colour control is one of the most common problems relating to the production of colour.Without the adoption of proper strategies, measuring colour correctly – thereby minimizing colorimetric errors – can be difficult. But why is controlling colour so complicated?
Here are the six key factors for an appropriate production process, as well as a few useful tips resulting from the experience and expertise of EuroColori.
1. 1. Colour can and must be quantified
Measuring colour is not an act of subjective interpretation.Furthermore, the use of specific, shared terminology enables customer requests to be effectively understood. Without adequate training, imprecise communication can lead to errors.If we strive to use the proper technical terms with our customers, requests like “I would like a slightly reddish colour” or “I’d prefer something a bit lighter” are replaced by a discussion in terms of DL*, Da* and Db* or DL*, DC* and DH*, achieving a more precise and decidedly more satisfying result.
2. A spectrophotometer is not a complete colour system
Although spectrophotometer calibration is an essential part of quantifying colour, it is only the first step in defining an optimal process for controlling colour quality.Colour management software that can analyse, trace and communicate colour, as well as a light cabinet, are also indispensable.Optimal conditions for properly managing colour are created when these three systems (spectrophotometer, colour management software and light cabinet) are used together.Each tinting system is also composed of parts that need to be mutually integrated and communicated with the user.With the objective of responding flexibly and precisely to the input and requests of customers and ensuring full respect of the real needs of those who make and utilize colours, paints and varnishes, EuroFormulations4 was created. This colour management software was produced by EuroColori, thanks to a team of professionals who develop colours and colorimetry solutions for architecture every day.
3. Analysing colour with a light cabinet
To satisfy customers and minimize the risk of complaints, we suggest adding the visual evaluation of colours to the quality control system by using a light cabinet.
4. There are three DE elliptical tolerance models
Many companies are accustomed to using spherical colour tolerance models based on DE*, a static tolerance system that at times is inadequate for certain areas of the colour space.In the past fifty years, much progress has been made in terms of measuring colour and developing better-performing tolerance models, leading to the creation of elliptical models like DEcmc, DE94 and DE2000.It bears reminding that DEcmc is an ISO 105-J03 international standard.
5. Designers and scientists speak different languages
Communication problems can arise when interfacing with designers and graphic designers.These professionals often use the L*C*h* language while scientists use L*a*b*.The L*C*h* language uses terms like luminosity, saturation and tone, a vocabulary at times unknown to those who develop tinting systems discussed in terms of red, green and blue.Fortunately, there are software programs that can translate communications between designers (L*C*h*) and scientists (L*a*b*), enabling colorimetric information to be shared.
6. All data must be measured under the same conditions
Once the colour management software, spectrophotometer and light cabinet have been selected, colour must always be measured and viewed under the same conditions.If for example we measure colour in L*a*b but our customer measures it in L*C*h, or our software reads data using illuminant D65 but we observe the same colour in a light cabinet with illuminant A, we cannot make decisions regarding the nature of the colour.It is therefore essential that all data be measured under the same working conditions, sharing this information with our customers.