Water base overprint colour bar

[sornchai]

My printed sheet has a colour bar at tail paper with a water base overprint .Should the density measurement have a water base over the color bar or no water base over the color bar? Which better and Why?
Thank you

 

[Jack liston]

I would not cover the color bar you would probably get a muted . density reading and color will be off

 

[Biggs]

Your density measurements wont be true to what the press is producing with an overprint. The press probably has a certain density target that you're looking to hit, say 1.2 for cyan (whatever the case may be) - you may be at the 1.2 , but with the overprint maybe it's measuring 1.5 - a new operator on the press might be tempted to bring down his or her density based on the incorrect value. Or, maybe you're expecting the extra saturation and know that a 1.5 is really about a 1.2 in reality.

Personally i would like the overprint removed from the color bar area. what if the overprint fluctuates or piles up in the tail area, your density could appear all over the place when in actuality it's stable and the aqua coating that's making it appear that way.

 

[sornchai]

I would not cover the color bar you would probably get a muted . density reading and color will be off

Thank you

 

[sornchai]

Your density measurements wont be true to what the press is producing with an overprint. The press probably has a certain density target that you're looking to hit, say 1.2 for cyan (whatever the case may be) - you may be at the 1.2 , but with the overprint maybe it's measuring 1.5 - a new operator on the press might be tempted to bring down his or her density based on the incorrect value. Or, maybe you're expecting the extra saturation and know that a 1.5 is really about a 1.2 in reality.

Personally i would like the overprint removed from the color bar area. what if the overprint fluctuates or piles up in the tail area, your density could appear all over the place when in actuality it's stable and the aqua coating that's making it appear that way.

Thank you

 

[Raf77]

You guys are wrong.
The colorbars should be coated as well as the rest of the sheet. Not coated colorbars will give you false density results in relation to coated image on printed sheet because that image is affected by coater. Any changes in absorption, light reflection etc. caused by coater on printed image, should be the same on colorbars, otherwise your measuring results will be far from what you're actually printing.

 

[turbotom1052]

If given a choice I will ALWAYS delete coating from color bars.