Colour Matching
I think, speaking from experience as a layman and as someone involved in the industry (now), that we tend to take colours for granted. Biologically speaking it is difficult to work out how many colours we can actually see, but most experts agree that the high end is around the 10 million colour mark. That is, we can see those colours, and recognise them as distinctively different.
Matching those colours to samples however, can prove taxing. Even worse, matching those colours to other colour schemes, can take hours out of the day. Of course, people tend to take this for granted, ‘can’t a computer do that?’ etc., We have to do this manually because at the end of the day it’s humans who are going to be looking at it and right now there are few matches to a human’s perception.
When it comes to most signs, there are a few choices for aluminium sign colours, white being the most prevalent, but when it comes to vinyl signs, or wide format printing, that’s where it gets a little more complicated.
Most vinyl colours are matched at GRS using Pantone or Mactac colour swatches. We use both as they have a wide variety of substrates to choose from, and according to the job we might have used some in the past and continue to use them now even though we may not use that vinyl colour for anything else. There is a dizzying array of choices. Let’s just say we stick to a selection of 50 or so, which does us just fine.
Computer designed wide format printing however, is another matter. Clearly, computer programs can create and manipulate a massive amount of colour, there are literally millions and millions of combinations of CMYK values (4!100 <- is this the right notation?). Getting the right colour can be somewhat difficult, and matching a colour to one a customer has provided, especially if we don't have a record of it, or what it looks like on vinyl, can be difficult.
One of the methods we use to match Pantone colours for our vinyl printing is by using their swatch and printing out a small colour block. Then altering the CMYK values, print out subsequent blocks and match the Pantone printed colour to what we see on the vinyl. The reason for this? Different inks print slightly differently on different substrates. What looks purple on satin paper might look maroon or red on vinyl and so depending on what substrate we're printing onto we have to get it right.
So as you can see, colour matching is more of an artform, and highly dependant on the eyesight and skill of one person, rather than relying on a computer which currently cannot do the job.
Update: As evidence of the difficulties faced by printers in such circumstances, I quote this article: ‘Virtual Proofing: A better predictor of color than hard proofs?‘ from PrintCEOblog.
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