colour consistency

[brettn]

Looking for others views...

If a 'proof' is done for a customer on a freshly calibrated printer (middle of day - printer warmed) and the next day after approval the job is started (middle of the day again, so everything warmed up - freshly calibrated again on same stock). Should the colour of the two samples be of consistent colour? The following days print had a decidedly yellow 'cast'. Only subtle, but the subject looked 'jaundiced'.

Techs seem to believe we should make adjustment to colour curves to match, but I am of the opinion that the above incident shows the printer to be inconsistent and in need of service of some sort.

Who's blowing smoke here? Me or them?

 

[maxon]

- freshly calibrated again on same stock

? Also, do you use a viewing booth of some sort.

 

[Curtis Johnson]

Color consistency is a challenge with any printer; some machines are better than others. Usually, it costs more to maintain accurate color; better printers, expensive spectrophotometers, higher maintenance levels, and color management training. Ask the Techs, what is the acceptable color error for the printer? If this is not acceptable for your standards; you may be adjusting the color curves or looking for a more color consistent solution.

 

[UberTech]

Looking for others views...

If a 'proof' is done for a customer on a freshly calibrated printer (middle of day - printer warmed) and the next day after approval the job is started (middle of the day again, so everything warmed up - freshly calibrated again on same stock). Should the colour of the two samples be of consistent colour? The following days print had a decidedly yellow 'cast'. Only subtle, but the subject looked 'jaundiced'.

Techs seem to believe we should make adjustment to colour curves to match, but I am of the opinion that the above incident shows the printer to be inconsistent and in need of service of some sort.

Who's blowing smoke here? Me or them?

To your credit you don't mention the model of machine. I would be looking at the last time the RIP was reloaded. Colour variations I have encounted that verge on the extreme are just about always related to the RIP looseing the plot.

I assume you have a hold/store queue you should get your designer to make up some colour swatches and keep them in the hold queue so you are reprinting the same file everytime. Print over the week and see what the difference is.

If you have an ES1000 you should download EYE-ONE share from Gretag macbeth (it's free) and measure the difference between days. Anything over 5dE isn't too flash. If this is process grey take your designer outside and shoot them for me.

On Konicas when the developer is over it's life consistency can be an issue.

 

[PGE]

Be sure to evaluate in good stable light conditions (preferably the same illuminant as the one used in your press (source) profile.
Although recent printer/media combinations have improved drying characteristics, there is still a time frame in which you should not judge colors too critical. Epsons with K3 inks have a fast drying characteristics but when you measure carefully, you can still see shifts in the first 30 min.
So when you compare a proof from yesterday with a fresh reprint , wait at least for 30 '
The stabilty , to my knowledge is rather good, Certification bodies like Fogra etc .. test on these parameters and they only allow a DE of 1.5 on the primary colors for what they call "repeatibilty" tests (for measurements after 1 h and 24 h).

If nothing has changed to the printer (consumables, or settings), and if all nozzle are printing accurately (which is not always visible on a nozzle check) then there is not really a need for recalibration ... unless the numbers fail.