First of all I apologise if you feel that I was denigrating you, that wasn't my intention. I was only purely criticising the statement and made the assumption with a question mark to indicate that further deliberation is necessary, nothing else. I'm not questioning your knowledge of printing industry or colour management. Only would like to see healthy conversation and debate about the topic. It's good to see other people who are passionate about the colour management and their job. My observations are based on my experience in the shop floor real world print production.
“Works first time, every time” I'm sorry to say this but I still don't believe it before I see it. Your statement is pretty dichotomous and I don't think people should be using this kind of statements, specially on the colour management and colour as like you said yourself "It's science, and it's art". Colour is complex phenomenon and so many disciplines involving like physics, chemistry, biology and psychology. I'm not making this stuff up either and my observation and statement is based on 15 years experience in printing industry and 11 years profiling and printing large format printers. I have worked in advertising, big magazine printer, newspaper and 2 different large format printing companies. Got training for Durst Rho in Italy their headquarters. Used several different profiling/RIP software like ProfileMaker, Binuscan, GMG, Caldera, Onyx etc. Profiled many different printers like Oce Arizona 180, Arizona 550XT, Encad Novajet, HP, Rho 160, 600, 351, Vutek 3300 and many more. I do Pantone and colour matching every day at my work. I know that some people have more experience but 15 years is pretty good experience to make observations.
Maybe with the profiles you're accustomed to creating or using. With Correct Color profiles, I have never seen this to be the case.
Our profiles are made using state-of-the-art GMG profiling package and GMG are one of the main players in the print colour management industry. These profiles are devicelink profiles with closed-loop profile optimization, where you can make as many iteration cycles until you reach the preferred dE tolerance. Also before profiling we make sure that we achieve maximum chroma with ink restrictions and the linearization is good, that we don't get any tonal banding. I really don't know how you can make better profiles then that?
Nowadays most of the profiling packages are pretty automated, that even non-experts can do high quality profiles. I don't think there is any trick to make perfect profile. You first make ink restrictions to max chroma then you make linearization and determine the ink limit and after that you make actual profile. On the profile you just need to determine colour separation settings and usually with default settings either using GCR or UCR you should get pretty good results.
So I kind of don't understand that what is so special on your profiles? Can you tell us bit more about your process and how do you build perfect profile and what software and spectro you are using? Also how do you deal with optical brightener issue and measurement errors as if you use UV cut filter you get different readings? Also different spectros give different readings and have deviation. How do you avoid anisotropy directional dependency from surface inhomogeneities when measuring colour? Also can you tell us how accurate are your profiles in dE colour difference. Remember that human eye can see difference 0.5 dE so your profile in gamut colours accuracy need to be under 0.5 dE to be perfect.
First time, every time. That's not marketing. It's simply a mathematical fact.
Exactly mathematical fact but not fact in practise and I think thats the issue here theory and practise don't always go hand in hand. I have been many training courses before. Problem with many trainees and teachers have is that they don't have clue how is the actual production in the shop floor and work as a printer operator and even if they have or they used to work for a company in the production they have forgotten how it was. I think they are teaching their own fantasy how it should be done, but don't realise that when you work fast base environment where most important thing is to get the job done and profits, you just can't always but theories in practice.
I've got several clients with Scitex XL's; several with VuTeks; several with older Dursts and plenty of clients with Jetis. They're every bit as stable as any other inkjet printers. I've gone back to some of them years later, and they haven't drifted at all.
That is really strange and hard to believe because I have experienced colour drifting from the beginning I started large format printing 11 years ago and since then I haven't operated any printer that wouldn't have some sort of colour drift.
Just which "big machines" would that be?
All our printers have some kind of drift but the big machines I was talking about are Vutek Ultravu 3300, Rho Durst 160, 600 and 351. On Rho 351 I have witnessed daily drift. Other printers we have are Oce Arizona 550XT, HP Z6200 and Lambda. I haven't calibrated other printers in daily basis so can't tell for sure if they drift daily but they do drift as always when I calibrate them they are off from the dE tolerance. Also another printer I can tell for sure that drifts daily is our proofer Epson Stylus Pro 4900. Also GMG do recommends to calibrate proofer and printers daily basis for accurate colour matching.
So as you can see, I have quite hard to believe that your clients don't experience colour drift at all. They must have controlled environment but even then I have hard to believe that they don't get colour drift at all on their machines. I'm not sure what is causing our printers to drift so much. I would assume that the main reason is because our print room and stock room is not controlled environment, I mean the humidity and temperature change daily as its kind of warehouse where heating is only on during the day, and weekends and nights it's off. So basically print room environment changes when the weather changes. Temperature can change from +5°C to +24°C and relative humidity can be anything between 20% to 70% so not so ideal. Also printer mechanical parts tends to worn and change. For example printheads gets clogged nozzles.
I have listed below other material and printer related real world situations when we get colour shift:
- Changing the roll. For example if we are printing big wall from many drops/tiles. We always try to fit those drops on the same roll and avoid printing different rolls, otherwise we might not be able to match the drops. More likely printer issue then material.
-Some materials like wallpaper we might get difference between the start and the end of the roll. So we can see difference between the first drop and the last drop on the same roll. Also the manufacture recommends to print rolls in manufacture batch order if we wanna match all the drops on separate rolls. This is because the manufacturing process of the material.
-If I need to redo one drop from big wall in another day we always get little colour shift never bang on same colour. Although usually colour shift is so small that we can get away with it.
-Also different manufacturing batches of Foamex sheets are different colour.
I could give more examples about colour shift but it would be like never ending story. Those are the main problems we have.
Would like to hear from other people, anyone else really don't have similar problems and don't experience colour shift at all on large format printing!?!?
In practice it's depending so many things like you said, inks, material, printer and environment (humidity, temperature). I would say with high gamut printers and good white paper you can get match to CMYK standards like FOGRA39 easily. Lower gamut printers yes but not all colours and not always that easy.
