How to establish ISO 12647 based quality control?

[yk_chin86]

Hi,
I am new to this field and currently our company is trying to establish ISO 12647 based quality control.

Currently our quality control is based on density measurement and visual inspection by printers (which in my perspective is very bias).

It is possible to establish quality control on printing based on ISO criteria such as Lab?

We are running on offset.

Kindly advise.

YK Chin

 

[Lukas Engqvist]

There are several QC software based on the media wedge. For density check are you using an auto scanner or manual spot measurements? In Gordo's blog there are some great articles that shed a light on what you can and what you cannot expect with density control, though just changing to Lab will not circumvent those problems.
It may help to look at it as two levels of quality control. The daily monitoring of production, which should be with a tool that the printer is well aquainted with. Second the monitoring of the process, which is done with routine checks using a media wedge or some other patch chart (measured in Lab).

 

[tmiller_iluvprinting]

Research SpotOn! software, an excellent tool for doing exactly what you are asking. SpotOn! Press Software:
Regards,
Todd

 

[yk_chin86]

There are several QC software based on the media wedge. For density check are you using an auto scanner or manual spot measurements? In Gordo's blog there are some great articles that shed a light on what you can and what you cannot expect with density control, though just changing to Lab will not circumvent those problems.
It may help to look at it as two levels of quality control. The daily monitoring of production, which should be with a tool that the printer is well aquainted with. Second the monitoring of the process, which is done with routine checks using a media wedge or some other patch chart (measured in Lab).

Dear Lukas,
I had goCurrently we are using manual spot measurements. As for now, some of our supplier evaluated our printed sheets through usage of light, standard and dark format which in my opinion is not accurate and bias. To make matter worse, most of our printing job involve trapping and usage of special color (Pantone).

Is there any way to measure color on printed sheet with trapping? or any quality control that is applicable to these?

Kindly advise

Thank you.

YK Chin

 

[Lukas Engqvist]

Trapping should not be a problem, if you mean trapping as in the means to avoid miss registration.
There are Lab targets for primaries and secondaries. Secondaries are dependant on the other kind of trapping i e magenta ink printed on top of wet cyan, this is why Lab values of both Primary and secondary colours are important. We found the closest match by without any control software, just using measuring device and plotting the values.
The main thing is to have a calibrated photo spectrometer. A good measuring device and the G7 guide will get you all the way there if you are meticulous.
After you confirm all your sub systems are stable it is basically a 1-3
1) Work out your SID (primary and secondaries)
2) Get your TVI curves sorted, per paper
3) Verify result.

Remember to document your state so that if things change you can see where and act accordingly. It's not difficult, just do it right

I don't understand how you mean light standard and dark. Are you talking of 25% 50% 75% tones?
You should be able to get a visual on those, but a good measuring device will get you actual numbers, and as you may see on other posts it can be essential to pay special attention to 0-10% and 90-100% screens, since many jobs today are fade to white or fade to black.

 

[Bloodsaler]

I advice you do a fingerprint test first,find your print condition,if your conditon is not ok,then check your press whetherr have mechanical problem.If have then fix it.Using spectrometer find your best density for primary colors,and the density range of it.Then try to find the best trapping color when the primary within the tolerance.But don`t foget focus on your ink sequence,this affect the trapping color a lot.