Industry standard spot color tolerance?

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Industry standard spot color tolerance?

Postby flexomonkey » Wed Feb 06, 2019 2:29 pm

Hi everyone!

What would the industry standard tolerance (delta E2000) be for a printed spot color for different production runs?

I was browsing the ISO 12647-6:2012 Part 6- Flexographic printing and I find conflicting information. One part says DE2000 of 6-
DE2000 6.JPG
DE2000 6.JPG (22.3 KiB) Viewed 647 times


But if I take a look at the Table referenced, it mentions DE2000 1.5!
DE2000 1.5.JPG
DE2000 1.5.JPG (31.04 KiB) Viewed 647 times


Does anybody know what is generally accepted?
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Re: Industry standard spot color tolerance?

Postby Gory » Wed Feb 06, 2019 3:14 pm

As I read it, that seems to specify no more than 1.5 from a standard, no more than 6 between different prints during a run, or different runs of the same job.

There is also the L:C ratio to consider.

I am not sure that I have ever encountered an 'industry standard'. Many customers set the spec at the high end/ high profile level. Many manufacturers set the spec they manufacture to if a customer does not specify one. For example, a perfume manufacturer is going to demand a much tighter tolerance than a customer who sells garbage bags. Coca Cola and McDonalds are very demanding for example, as their color is part of their brand identity.
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Re: Industry standard spot color tolerance?

Postby flexomonkey » Wed Feb 06, 2019 3:29 pm

Hi Gory,

Thanks so much for your response. Maybe I'm understanding incorrectly, but if you're always 1.5 DE2000 from your standard, how can you have a difference of 6 for different prints?

Would it be 1.5 for your starting point and then press variations can move you all the way to 6?
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Re: Industry standard spot color tolerance?

Postby Gory » Thu Feb 07, 2019 7:12 am

It's a bit of a black art to me also. However, if you start up 1.5 clean and light, drift 1.5 from that, then next run you started up 1.5 dark and dirty, then drifted 1.5 from that, I believe you could get to a differential of 6.

Most of the industry - generally speaking - that I have encountered sets a DE spec of 2.0 from standard, and try to run within that window - you could still get a difference greater than that within a run (2.0 light v's 2.0 dark would be greater than 2.0 difference, but they would both be at 2.0 from standard)

I also try to use my eyes when something is running, and confirm data with a visual - sometimes a specrtophotometer will 'pass' a color that just looks too far from standard.
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Re: Industry standard spot color tolerance?

Postby Frank Burgos » Thu Feb 07, 2019 10:26 am

I'm reading that the sample that you OK to run, the "OK print", must be within DE 6 of the specified target and that during the run the spot color should deviate no more than 1.5 during the run.
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Re: Industry standard spot color tolerance?

Postby flexomonkey » Thu Feb 07, 2019 1:26 pm

Gory, from your explanation I understand that each printed sample should be DE1.5 from our target, but since that 1.5 can move in any number of directions, if I measure print vs. print my DE could go up to 6. This makes sense to me.

Frank, from your explanation I understand that my first ok print should be within DE6 of my target, and I shouldn't deviate more than 1.5 during that run from that original ok print. This also makes sense to me.

I wonder what most people do?
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Re: Industry standard spot color tolerance?

Postby Frank Burgos » Thu Feb 07, 2019 1:29 pm

I think most people shoot for 2-3, unless compelled by an external force, like a customer, to hold to tighter and specific aims.

One client of mine prints for P&G. They demand, on a particular product, 2.5 for their logo spot color and 3.5 for their non-logo spot color. Don't recall the tolerance math. Maybe 2000
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Re: Industry standard spot color tolerance?

Postby Frank Burgos » Thu Feb 07, 2019 2:07 pm

I thought I’d cite a little bit of a case study, given the conversation.

In 2018 I led a project for a client to become GMI certified. GMI certification focuses on process control and documentation, equipment maintenance, training procedures, operator capability, and equipment performance. We did a Narrow web label flexo press and an HP Indigo digital press.

Under the guidelines, the color component of process control states:
“Color measurement of the spot color reference to the drawdown sample should not exceed ΔE2000 1.5 on white backing”
“Color measurement of the spot color reference to the press OK should not exceed ΔE2000 2.0 on white backing”

In addition:
Spot colors are held to ΔE2000 2.8
CMYK primaries are held to ΔE2000 3.5
CMY overprints are held to ΔE2000 3.5

There are other specifications and tolerances, but these are the relevant ones. They are, indeed, industry standards.

To become certified, we were held to ISO 12647-2, or offset standards, on a flexo press and a digital press. My colleagues and I were puzzled about this. It turns out that package suppliers may be insisting that flexo and offset folks print to the same aims. That makes sense, to me.

I was watching a color webinar and Steve Smiley was the speaker. He’s a highly knowledgeable color expert. In that presentation, he stated that very same thing; that package buyers are insisting on one standard. I don’t recall whether he mentioned flexo, offset and digital or just one technology.

Hope this helps. Sorry for not mentioning it earlier.
Frank
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Re: Industry standard spot color tolerance?

Postby flexomonkey » Thu Feb 07, 2019 4:36 pm

Hi Frank, thanks so much!!

We do have some customers who have defined specific tolerances, however other clients have asked us to go by ISO standards, which are still not quite clear to me!
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Re: Industry standard spot color tolerance?

Postby Fuzz » Fri Feb 08, 2019 10:11 am

Frank you say, They are, indeed, industry standards.

Where are these standards found? who created them?

Not bashing, I like these if they are indeed a accepted industry standard. Just wondering where they can be found, so I can relay to questioning customers.
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Re: Industry standard spot color tolerance?

Postby Frank Burgos » Fri Feb 08, 2019 11:38 am

Hi Fuzz,

When a company goes through GMI certification, they gain access to a website with access to various resources, including guidelines. The guidelines point to relevant industry standards. For example, here are specs on color measurement conditions. Note the relevant industry ISO standards:

Color Measurement Conditions
Density Measurement is Status T, Absolute, in accordance with ISO 5-3:2009
Measurement geometry is 0/45, in accordance with ISO 13655:2009
Colorimetric observer standards is 2°, in accordance with ISO 13655:2009
Illuminate D50, in accordance with ISO 13655:2009
CIELAB color system, the color attributes are L*, a* and b*
Color difference formula: ΔE2000 Color Space kL* = 1 kC* = 1 kH* = 1, in accordance with ISO 13655:2009
Measurement Illumination Condition: M0, in accordance with ISO 13655:2009
Substrate white: L* = 94.00 a* = 0.00 b* = -2.00, in accordance with ISO 12647-2:2004 Amd. 1:2007
Substrate backing: L* = 94.00 a* = 0.00 b* = 0.00, in accordance with ISO 13655:2009

In addition, the are standards and the corresponding aims for TVI, grey balance, spot color, registration, trapping, and other stuff.

The following link takes you to a page on WhatTheyThink?, describing GMI certification. http://whattheythink.com/articles/75469 ... practices/

GMI has ties to certifications and memberships, including:
o G7
o IdeAlliance
o Flexographic Technical Association
o Printing industries of America
o Others
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Re: Industry standard spot color tolerance?

Postby Frank Burgos » Fri Feb 08, 2019 11:39 am

If any of said customers needs help becoming certified, please feel free to have them contact me.
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Re: Industry standard spot color tolerance?

Postby Frank Burgos » Fri Feb 08, 2019 11:41 am

Please note that the reference to 12647-2 is not mistake. We aimed for offset standards.
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Re: Industry standard spot color tolerance?

Postby Fuzz » Fri Feb 08, 2019 12:00 pm

:smile: LOL....ISO would have satisfied me. Thanks for all the info and all you do!
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Re: Industry standard spot color tolerance?

Postby Frank Burgos » Fri Feb 08, 2019 12:04 pm

Bro. If you ask me what time it is, get ready to learn how to build a watch.
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