Hi Bob,
Something is definetly a miss with the current printing of the Pantone coated & uncoated books pertaining to the PMS 123 yellow. The coated version lacks saturation, looks washed out, for a color that is full strength.
PMS123C fits fairly well visually in between PMS122C and PMS124C, and IMO, is printed at a reasonable ink film thickness (based on samples we've done with PMS123...more below). Why would you decide it looks washed out? Moreover, PMS123U also fits between PMS122U and PMS124U. This issues in question between coated and uncoated occur in more than just PMS123.
If you don't have a current edition to view, I can only describe the difference as if you look at 123 coated and compare it to 165 coated.The difference would represent what the 123 coated looks like versus the 123 uncoated in the current edition.
That example is pretty extreme from what I'm seeing in the multiple versions of PMS guides I have here. The differences I'm seeing are more like PMS123c to PMS137C, but your point is taken, its a significant visual difference.
The same ink will not look this different from coated to uncoated at the same film weight.
Depends on how you define weight...if by density, than I disagree. If by ink film/volume...well, I still disagree.
I'm trying to keep an open mind here, but now you went and made me get all inky.
We happen to have a can of PMS123, and after tapping out some samples, I'm sticking with my original story and attribute these results almost entirely on paper attributes. We don't have a Little Joe draw down machine on site (which, btw has a larger ink volume for use with uncoated paper), so this was done by hand, and therefore not very scientific, but the results were pretty evident to my press guys and I, and I maintain that PMS123 will look significantly different, along the same lines as the Pantone book examples, when printed on uncoated stock versus coated stock.
I took density readings of the both books D50 2* Status T Absolute. The coated book reads .80 and the uncoated is .93.
This was taken using the filter with the highest value no doubt, which is yellow. Although this is a "yellow" ink, this may or may not be the most appropriate filter for a Pantone color. If we use the "visual" filter, the densty values are likely much closer...I'm getting approx .015 and .021 for coated and uncoated. If we take the "Special" color channel reported by Xrite's MeasureTool with an i1Pro spectro, the results are 1.14 and 1.14 for coated and uncoated (a value derived from 410nm reflectance). So what manner was Pantone using to measure density, if any? We don't know, but the results are ambiguous anyway.
But lets say we match the yellow filter density between PMS123 printed on coated and uncoated from the samples I created with my ink and paper:
PMS123 on Coated
Density
C: .07
M: .30
Y: .87
K: .17
Lab values
L*: 83.38
a*: 14.3
b*: 71.34
PMS123 on Uncoated
Density
C: .09
M: .44
Y: .89
K: .23
Lab values
L*: 77.41
a*: 25.79
b*: 61.13
delta E comparisons between the two yeild a deE76 = 16.52 (dE2K = 9.75)
So, if we stop look at the density filter readings where we get the highest values, we see that the yellow filter gave us the highest value, but there is a significant difference in the magenta filter values. If we then target the magenta filter for an aim:
Density of PMS123 on Uncoated
C: .08
M: .29
Y: .62
K: .17
Lab values of PMS123 on coated
L*: 82.94
a*: 15.36
b*: 48.89
delta E comparisons between the two yeild a deE76 = 22.5 (dE2K = 7.09)
Note that the dE2000 value was lowered, indicating a somewhat closer visual result, but the sample still looks redder as the yellow (b*) value is way down.
Now, as far as ink film thickness, I had PMS123 tapped out on uncoated, and over the edge onto a matte coated stock, yeilding the same ink film over the two substrates. The Lab values differed significantly:
Lab values of PMS123 on Uncoated
L*: 80.9
a*: 19.3
b*: 54.2
Lab values of PMS123 on Matte
L*: 78.8
a*: 19.1
b*: 80.7
So at the same ink film thickness (again, not a scientific test) the L* and a* values are fairly close, but the b* value for uncoated is much lower and looks much redder.
In short, from my actual ink and paper samples, the PMS guide is not at all far off from reality.
from Mike's PMS123 stained keyboard.