Delta E

[Stephen Marsh]

Stephen,

The labels are produced in sheetfed offset with non uv inks. The substrate is BOPP (Biaxially oriented polypropylene) Here is a pic of the label in question laid on top of the first production run.

Tamale

Thanks for the image.

The left hand side shows the variation between runs.

The centre/right hand side appears to be much closer together.

Depending on the colour builds of both areas, chances are if they tried to make the left hand side match between runs, the centre area would then be off between runs. If the press operator had a gun held to his head and was asked to pick an area of the label to match – they would probably pick the centre area (I am presuming this is some sort of tub label?).


Stephen Marsh

 

[tamale]

Thanks for the image.

The left hand side shows the variation between runs.

The centre/right hand side appears to be much closer together.

Depending on the colour builds of both areas, chances are if they tried to make the left hand side match between runs, the centre area would then be off between runs. If the press operator had a gun held to his head and was asked to pick an area of the label to match – they would probably pick the centre area (I am presuming this is some sort of tub label?).


Stephen Marsh

Stephen, the issue is actually from top to bottom. The bottom label being the new run. The gold colour to the right of the letter G is a spot gold.

 

[kansasquaker]

Could you elaborate on this (which is likely what the printer is referencing):

Gordo. I'm assuming here that the customer is talking about the reproduction of a specific cmyk build, not the solid densities of cmyk. To my knowledge there is no standard for that. Customers don't buy color bars. For example if you send me a job with various contone values, I won't blindly promise you that I'll hit ALL of them within 3dE or even 5dE. If you say match a single cmyk build (e.g. I'm to cheap to print my five color job with a match plate) to within a certain tolerance, my presses print tight enough that I can pretty much hit that color for you every time if I'm paying attention to it. It's not the same thing as having the whole sheet in balance per se. Did I explain what I mean better?

 

[tamale]

Kansasquaker, I really like «Customers don't buy color bars» that's exactly what I will be telling them!

Thanks,

Tamale

 

[gordo]

Gordo. I'm assuming here that the customer is talking about the reproduction of a specific cmyk build, not the solid densities of cmyk. To my knowledge there is no standard for that. Customers don't buy color bars. For example if you send me a job with various contone values, I won't blindly promise you that I'll hit ALL of them within 3dE or even 5dE. If you say match a single cmyk build (e.g. I'm to cheap to print my five color job with a match plate) to within a certain tolerance, my presses print tight enough that I can pretty much hit that color for you every time if I'm paying attention to it. It's not the same thing as having the whole sheet in balance per se. Did I explain what I mean better?

Yes, absolutely. The original post wasn't clear about what was being measured/toleranced which is why I asked, in the post you responded to,: "The industry spec, ISO 12647-2 for tolerance is for a Delta E <5 for solid ink patches." (The OP said that his experience was with density not spectrophotometry which lead me to think he was talking about the solid patches in the color bar).

So to clarify I asked the OP "Is the printer saying that an individual press sheet is within a Delta E <5 for solid ink patches? How does the printer know that through the run the variation isn't greater than 5? Is your complaint about color variation in the live image area?"

Later I posted "From your description it sounds like the problem is a lack of effective communication regarding setting expectations for the job."

And that's what you're talking about and I totally agree with you.

 

[Johu]

Stephen, the issue is actually from top to bottom. The bottom label being the new run. The gold colour to the right of the letter G is a spot gold.

Before reading the above answer, my first thougt was the same as what Stephen thought. That the more "reddish" label was the new one. Now knowing that it is the other way around putting myself to the pressmans shoes looking at the label he actually might have manually adjusted the press in order the make the two colors appear as different shades of the same color. I could easily see that happening. But if that was the case then a proper color proof or a sample of the previously printed label could have been the fix.