Defining “Acceptable” Colour

Determining what is an acceptable colour match can be challenging, especially if there is a group of people assessing the colour. It’s not uncommon for 3 people to see three different versions of the same colour.  How can this be, you ask.

Here are a few fun facts about colour:

  • Two identical Pantone color guides were compared with 452 patches measured. The patches had deviations up to Delta E*ab 9.46 and an average of 2.22%, well over 3 Delta E*ab!
  • The average colour tolerance in the printing industry is around 2.5 Delta E CMC. 
  • The differences between two Pantone guides is higher than our industry standard!
  • Women tend to see more variation is colour compared to males. 
  • Men tend to lose their ability to see subtle colour variations as they age, and women hold onto that ability longer. 
  • Red is the first colour a baby sees, white is the safest car colour, a black car is 12% more likely to be involved in a crash and chickens are very sensitive to coloured lights.  

So what can we control when it comes to colour: 

When comparing colour it’s important to understand the terminology and Delta E is the most important one of them all. Delta E or DE comes in a few variations or different formulas. You may see Delta E 2000, Delta E CMC, Delta E*ab, Defat E 1976 and the list goes on. I personally use Delta E CMC as it is more in line with what our eyes see.

The best way to control colour is to remove the subjectivity and used a hand-held device. Techkon (SpectroDens) and X-Rite (eXact) sell great devices that can take the guesswork out of colour evaluation. You can load all your customers colours into the device, add a Delta E tolerance and set a pass-fail. That way anyone that can operate a stapler can now approve colour. Even better they can check the colour at the start, middle and end of the run. 

Another cool feature with a hand-held device is the “compare function”. Let’s say you printed a job on one printer and due to scheduling you need to move it to another printer. This change will require you to ensure the colour is acceptable. Easy, measure Sample A from the first printer and using the compare function measure the sample from the second printer. You will get a DE difference. Question:  will the prints be shown side by side or at different locations? Side by side will require a much lower DE, something in the range of 1.5 or less. If the prints are 10 miles apart then the colour tolerances can be higher. This brings us to what are acceptable tolerances. 

Production Tolerances:

In the graphics and printing industry we have specific tolerances. We also have limitations due to fluctuations in our equipment. A traditional offset printing press can have a colour variation of 2.5 DE throughout the run. Newer Inkjet presses and other digital devices are bringing that number under 1 DE. It’s imperative that you learn what your devices can do. By measuring a device regularly, you begin to understand the heartbeat of the device. 

Suggested Tolerances for Colourimetric deviation.

Customer A may be very particular when it comes to colour but Customer B is not as meticulous.  Understanding your customers and setting a tolerance for each customer is imperative. I would separate my top customers into groups – production levels A and B. Level A requires a colour match of 1.5 or less (digital) and level B is 3.5 or less (digital). Armed with realistic tolerances you can let the device decide if colour is good-to-go our needs a CSR’s approval. Keep in mind that you need to establish tolerances that fit your equipment 

What’s most important is to stick with one DE formula when discussing colour be sure to specify which one you used. 

So, what is the take away? If you are a baby driving a red car and a female chicken crosses the road, don’t look at the coloured lights. 

You can take an online colour test at this URL