Another density question.

[FlexoGrunt]

Situation:

XRite handheld densitometer being used.

what I have noticed is that the SID readings from the DENSITY ABSOLUTE are about .08 - .10 higher than the DOT -PAPER.

The press uses DENSITY ABSOLUTE on every cmyk job.




Here is my question: *I* know they have the option to use -PAPER as a setting when scanning using DENSITY but is it causing enough of a variance to warrant concern and bring it up to production? Or is this irrelevant once we do the color mapping portion of the testing (we map all the stocks and finishes).

 

[rich apollo]

What testing are referring to?

How much variance do you see in the substrates?

 

[FlexoGrunt]

We are measuring dot gain with this first test. CMYK down at production speed. Also this is the exact same print piece. When the press operators measure it using the "density" selection on the densitometer they are getting 1.49 in the black. That menu selection is set to Absolute in the options.

When I started scanning using the "dot" selection it prompts me to scan the paper (-paper setting in options as I can't set it to absolute in DOT and I wouldn't think I'd want to anyway). Then I scan the same swatch and I get either [email protected] density or 1.4 V (very rarely). When I try to scan the actual dots they come up as -xxx% (this makes sense when the densitometer is thinking it's yellow). So the total difference is .09 with some as high as .12 (this seems like a LOT).



I have forced the XRite to only see V (visual) and I'm scanning BUT I am curious how much of a difference this makes on color if they are measuring using absolute and I am measuring using -paper? Should we all be measuring using -paper setting??

 

[meddington]

To measure dot gain you have to measure the 0%, 100% solid and the tint. Measuring the substrate is required as the instrument needs to know what 0% measures in order to calculate gain, and the solid will be displayed as -paper when measured. Paper density can vary sheet to sheet, but I'm not taken aback by a difference of .09 to .12 between absolute and -paper solid density. Press operators should be using absolute density readings if targeting a "standard" based on absolute density, which all to my knowledge are. I'm a bit confused on your discussion of the yellow, and not sure what status or filter your using to render a yellow density of 1.6.

 

[FlexoGrunt]

Since the black is scanning so light using -paper the densitometer actually sees more yellow in the color than anything else. So it thinks we're printing ultra high yellow.

I forced it to scan visual and my numbers seem to be in line with expectations so I will continue there. When I saw that much of a shift between -paper and absolute it had me wondering how we can get elements across materials (we print on quite a few different ones). Flexographic printing tends to push variability to the limit anyway.

 

[TonyN]

Compare the blue led

Compare the blue led

Since the black is scanning so light using -paper the densitometer actually sees more yellow in the color than anything else. So it thinks we're printing ultra high yellow..

3 years back i bought 4 DensiEye 100's to replace some 7 year old devices of the same type. The new devices gave a different measurement in yellow when compared with the old ones and also with other densitometers from Techkon. Al other colors gave a good result.
Finally Xrite replaced my 4 new DensiEye's because the used blue led (wish measures the yellow density) was from a different type/brand then all the other devices we use. You should compare your equipment with some other devices from the same type and find out if there's a big difference.