Consistent colour

[Jose Martinez]

Helllo I'm Jose from Spain, I'm a new member of Primt Planet and is a big pleasure.
I have a question. How many sheets do you need to grt a consistent or stable color?
Sorry for my bad English.
Thanks for your help.
Jose.

 

[SheetSqueezer]

It mainly depends on a few basic things:

1) What make and model of offset press?
2) What tech is being utilized?
3) How dialed in is the press with ink/chemistry compatibility?
4) How well does the pressroom communicate with prepress?

Even with ideal circumstances and everything under control as much as possible, consistency and stability can still end up varying some from job to job. Sometimes the key is in not only knowing what you have, but also what you can (or can’t) do with it.

The short and most preferable answer to your original question is somewhere between 50-250 sheets.

 

[Asures]

Thats a very broad and subjective question Sir.

What is your process method to ensure that color is where you feel is right? Are you using a scanning device or hand held to measure color?

Can you give us a little more information about your shop (equipment, print application, color calibration, are you targeting visual or G7) ?

 

[Jose Martinez]

Hello, Sheetsqueezer
- The offset printer is a Mitsubishi V3000LS 5colors + Tower.
- it is conventional printing.
-Our measuring device is an in-line Intellitrax spectrophotometer
The press machine is very good adjustment rollers, ink/chemistry, blanket tensile ....erc I'm the responsible that making sure t are correct. I'm tge tesponsoble of colors curve.
The comunication betwen pressroom and pre press is excellent we are a good team we work in the same direction.

 

[Jose Martinez]

Thats a very broad and subjective question Sir.

What is your process method to ensure that color is where you feel is right? Are you using a scanning device or hand held to measure color?

Can you give us a little more information about your shop (equipment, print application, color calibration, are you targeting visual or G7) ?

Hello Asures, the process method that we use an in line Intellitrax and we works with ISO 12647-2 with Fogra 39 profile in the plotter and on the machine.

 

[Jose Martinez]

SheetSqueezer and Asures sorry for my bad English.

 

[DeltaE]

IMHO, there is no answer for your question. It depends on your jobs (artwork), the artwork with heavy ink coverage, it becomes stable faster than the low ink coverage artwork (in case your ink setting is correct).
Basically in my area, they could set the allowed waste sheets from 250 - 500 sheets per CMYK + 2 spot colors depends on run-length and quality of the jobs.
Hope this help!
DeltaE

 

[Jose Martinez]

I understand what you mean Delta E, our work is usually of very high quality, runs of 5000-6000 copies normally and CMYK normally without direct colours, your waste of sheets is very similar to ours.

 

[Jose Martinez]

Another question, how much time would it take to prepare for quality work?

 

[xmoles]

Hello

If you have intellitrax you are already guaranteed that the waste will be low, as long as you maintain the system properly.

Also, the intellitrax system is continuously making inkwell corrections.

You could record a maximum number of sheets to know if what comes out of the machine is in tolerance.

 

[Jose Martinez]

You could record a maximum number of sheets to know if what comes out of the machine is in tolerance.

Hello Moles I don-t understand this part, How should I do it?
Thank you very much

 

[SteveSuffRIT]

Variation is the result of change, either known (ink key adjustments) or unknown. Variation is the opposite of consistency or stability. All should define a duration or period between sheets. A common interval is every 500 shts. Any press stoppage will immediately cause color variation since the delicate lithographic balance between ink & water has been disrupted by a disturbance. The closer your first makeready (MR) pull (sample/measurement) is to the target aim, the less time, sheets, effort, money is needed to get to the desired target aim. This is why CIP3-4 prepress ink key presets and a calibrated press-to-proof are so important. I think many older technology 40" sheetfed presses can achieve a color OK (close/good enough commercially acceptable color match) after 2 pulls of 200 sheets each.

Do you stop/restart the press between MR pulls or does your MR run steady at run speed and you get the OK on the fly?

Regardless of the technology and process, most decisions are ultimately a business/financial/productivity one, hopefully quality too.
It often comes down to a compromise or tradeoff between quality and cost. A closer match will need more time and paper which costs more. Was it estimated for, will the customer/market pay for it, am I making enough profit?

 

[Jose Martinez]

Variation is the result of change, either known (ink key adjustments) or unknown. Variation is the opposite of consistency or stability. All should define a duration or period between sheets. A common interval is every 500 shts. Any press stoppage will immediately cause color variation since the delicate lithographic balance between ink & water has been disrupted by a disturbance. The closer your first makeready (MR) pull (sample/measurement) is to the target aim, the less time, sheets, effort, money is needed to get to the desired target aim. This is why CIP3-4 prepress ink key presets and a calibrated press-to-proof are so important. I think many older technology 40" sheetfed presses can achieve a color OK (close/good enough commercially acceptable color match) after 2 pulls of 200 sheets each.

Do you stop/restart the press between MR pulls or does your MR run steady at run speed and you get the OK on the fly?

Regardless of the technology and process, most decisions are ultimately a business/financial/productivity one, hopefully quality too.
It often comes down to a compromise or tradeoff between quality and cost. A closer match will need more time and paper which costs more. Was it estimated for, will the customer/market pay for it, am I making enough profit?

Hello, yes I stop/restart the press between MR pulls, 3 or 4 times,We print 125 sheets each time aprox depending on the job.
I think Many of our jobs are not economically profitable

 

[SteveSuffRIT]

Did you ever consider that if you idle the press between pulls, for that 2-3 min that you are adjusting ink keys, the oscillator/vibrator rollers are evening out the ink key settings. Then when you start back up it's taking time and sheets to show the actual ink setting from the fountain blade own to the paper. Between pulls, consider actuall stopping the press and not idling. This way it will take less sheets to get a true response to any adjustments made.

 

[SheetSqueezer]

Did you ever consider that if you idle the press between pulls, for that 2-3 min that you are adjusting ink keys, the oscillator/vibrator rollers are evening out the ink key settings. Then when you start back up it's taking time and sheets to show the actual ink setting from the fountain blade own to the paper. Between pulls, consider actuall stopping the press and not idling. This way it will take less sheets to get a true response to any adjustments made.

In the post above yours, OP literally says that he stops/restarts the press during make-ready pulls. He doesn’t idle the press… While I too might have my own preferred way of setting up on a job, as every seasoned operator should*, I don’t know if I personally would be too quick to get behind this philosophy.

*asking for advice on the internet can truly be a roll of the dice, at times

 

[Jose Martinez]

Did you ever consider that if you idle the press between pulls, for that 2-3 min that you are adjusting ink keys, the oscillator/vibrator rollers are evening out the ink key settings. Then when you start back up it's taking time and sheets to show the actual ink setting from the fountain blade own to the paper. Between pulls, consider actuall stopping the press and not idling. This way it will take less sheets to get a true response to any adjustments made.

Sorry i think i have explained myself wrong, becsuse of my bad English, i never leave the machine stopped when i adjust a job i leave it on idle.
Thanks and sorry for my bad English

 

[Jose Martinez]

In the post above yours, OP literally says that he stops/restarts the press during make-ready pulls. He doesn’t idle the press… While I too might have my own preferred way of setting up on a job, as every seasoned operator should*, I don’t know if I personally would be too quick to get behind this philosophy.

*asking for advice on the internet can truly be a roll of the dice, at times

Hello, i'm sorry about what i said above i made a mistake when i wrote it in English, i never stop the mschine ehen i adjust the work, i leave it on idle, i agree that asking for advice on the internet is risky, but then everyone draws their conclusions and try what seems the most interesting.... then every workshop doesn't have to work in the workshop another, this is where the operator has to show their experience and knowledge to achieve that difficult balance between quality and production.
Thank you very much for your help.