That
said, the scan of a QTR Calibration Mode print on Inkpress film and
then contact printed on the platinum print paper is close enough to see
what is going on. Below the scanned image I have the Excel graphs of
the PK, LK, LLK and Y inks. The graphs are up to "50%" on the
Calibration Mode print, but have as the starting point the paper outside
the film base.
http://www.paulroark.com/BW-Info/QTR-Calibration-Mode-Platinum-3880-24.pdf
From what I've seen so far, I am going to recommend the M and C colors be ignored and not used.
Your platinum print made using the inkseparation page printed with an Epsonn K3 inkset gives similar results to what I get with carbon printing using 50% calibration. Like you, I would advise not using the M and C colors, and of course LLK, because they block so little UV light that they serve no useful purpose in a QTR profile for making digital negatives for UV sensitive alternative processes.
There are many ways to create profiles for digital negatives using the Epson K3 inkset. The attached profile is simple to understand and easy to adjust for specific processes. It uses a single gray scale where all all curves follows the K. I have taught this QTR profile for several years at my carbon transfer workshops and it gives results as good or better than any of the other methods I have used to profile with QTR for digital negatives using the Epson K3 ink set. And just for the record, carbon is a process that is as sharp or sharper than silver, and carbon prints are often made on very smooth papers similar to those used for silver. In my personal work with carbon I use a QTR profile of my own creation based on a all gray ink set using various mixtures of Epson K3 PK, LK and LLK. I considered using the Cone inks for my ink set but found that they did not dry as fast as the Epson OEM inks.
Adjustments that can be made to the profile are.
1. To increase printing density by 10% just increase the Limit of the K, Y and LK by 10%. To decreae density by 0% decrease the Limit of the K, Y and LK by 10%.The other inks are set at 1 just to make sure some ink is being used every time the printer is used.
2. To linerize you can use either a curve for the K ink, which is followed by the Y and LK, you can use the LINEARIZE command, or indeed do one on top of the other.
It is important to note that the commands that control gray highlights, gray shadows, and gamma, are not operative with this profile. However, for the profile to install some value must be included, so the numbers 4, 4 an 1 are entirely arbitrary as any value will work.
In testing profiles for carbon printing I make extensive use of a UV transmission densitometer as it saves a lot of time in evaluating step wedges. I also linearize with an iOne spectrophotometer.
#PRINTER=Quad7800
#CURVE_NAME= Carbon100 #Based on Carbon Tissue #230, 14 grams of Black Cat Ink + 2 grams of Mixol #23 Dunkelbraum, with tissue coated to a wet height of 0.9mm.
#Profile when printing a step wedge gives a DR (density range) of approximately log 2.05.
#With Tissue #230 sensitize with a 4% potassium dichromate solution, diluted 1+1 with acetone, approximately 10 ml per 8X10 sheet, applied in two coatings with a roller. 350 ULF units.
GRAPH_CURVE=YES
N_OF_INKS=8
DEFAULT_INK_LIMIT=100
LIMIT_K=25
LIMIT_C=1
LIMIT_M=1
LIMIT_Y=25
LIMIT_LC=1
LIMIT_LM=1
LIMIT_LK=50
LIMIT_LLK=1
GRAY_HIGHLIGHT=4
GRAY_SHADOW=4
GRAY_GAMMA= 1
CURVE_K= "0;0 100;100"
COPY_CURVE_C=K
COPY_CURVE_M=K
COPY_CURVE_Y=K
COPY_CURVE_LC=K
COPY_CURVE_LM=K
COPY_CURVE_LK=K
COPY_CURVE_LLK=K
LINEARIZE="14.89 16.51 18.47 20.86 23.83 27.27 31.12 35 39.69 44.62 49.73 54.83 60.24 66.38 72.96 80.47 85.47 90.59 93.75 94.69 95.15"
http://www.paulroark.com/BW-Info/QTR-Calibration-Mode-Platinum-3880-24.pdf
From what I've seen so far, I am going to recommend the M and C colors be ignored and not used.
Your platinum print made using the inkseparation page printed with an Epsonn K3 inkset gives similar results to what I get with carbon printing using 50% calibration. Like you, I would advise not using the M and C colors, and of course LLK, because they block so little UV light that they serve no useful purpose in a QTR profile for making digital negatives for UV sensitive alternative processes.
There are many ways to create profiles for digital negatives using the Epson K3 inkset. The attached profile is simple to understand and easy to adjust for specific processes. It uses a single gray scale where all all curves follows the K. I have taught this QTR profile for several years at my carbon transfer workshops and it gives results as good or better than any of the other methods I have used to profile with QTR for digital negatives using the Epson K3 ink set. And just for the record, carbon is a process that is as sharp or sharper than silver, and carbon prints are often made on very smooth papers similar to those used for silver. In my personal work with carbon I use a QTR profile of my own creation based on a all gray ink set using various mixtures of Epson K3 PK, LK and LLK. I considered using the Cone inks for my ink set but found that they did not dry as fast as the Epson OEM inks.
Adjustments that can be made to the profile are.
1. To increase printing density by 10% just increase the Limit of the K, Y and LK by 10%. To decreae density by 0% decrease the Limit of the K, Y and LK by 10%.The other inks are set at 1 just to make sure some ink is being used every time the printer is used.
2. To linerize you can use either a curve for the K ink, which is followed by the Y and LK, you can use the LINEARIZE command, or indeed do one on top of the other.
It is important to note that the commands that control gray highlights, gray shadows, and gamma, are not operative with this profile. However, for the profile to install some value must be included, so the numbers 4, 4 an 1 are entirely arbitrary as any value will work.
In testing profiles for carbon printing I make extensive use of a UV transmission densitometer as it saves a lot of time in evaluating step wedges. I also linearize with an iOne spectrophotometer.
#PRINTER=Quad7800
#CURVE_NAME= Carbon100 #Based on Carbon Tissue #230, 14 grams of Black Cat Ink + 2 grams of Mixol #23 Dunkelbraum, with tissue coated to a wet height of 0.9mm.
#Profile when printing a step wedge gives a DR (density range) of approximately log 2.05.
#With Tissue #230 sensitize with a 4% potassium dichromate solution, diluted 1+1 with acetone, approximately 10 ml per 8X10 sheet, applied in two coatings with a roller. 350 ULF units.
GRAPH_CURVE=YES
N_OF_INKS=8
DEFAULT_INK_LIMIT=100
LIMIT_K=25
LIMIT_C=1
LIMIT_M=1
LIMIT_Y=25
LIMIT_LC=1
LIMIT_LM=1
LIMIT_LK=50
LIMIT_LLK=1
GRAY_HIGHLIGHT=4
GRAY_SHADOW=4
GRAY_GAMMA= 1
CURVE_K= "0;0 100;100"
COPY_CURVE_C=K
COPY_CURVE_M=K
COPY_CURVE_Y=K
COPY_CURVE_LC=K
COPY_CURVE_LM=K
COPY_CURVE_LK=K
COPY_CURVE_LLK=K
LINEARIZE="14.89 16.51 18.47 20.86 23.83 27.27 31.12 35 39.69 44.62 49.73 54.83 60.24 66.38 72.96 80.47 85.47 90.59 93.75 94.69 95.15"