Profiles
Profiles are printer curves that counteract the variable contrast of alternative photographic processes.
After finding the RGB values and density of the “Just White” and “Just Black” points in a print of the TruNeg Gradient, they were entered into the program, which applies the principle that the negative logarithm is inversely proportional to the positive logarithm to calculate the target density of 10 in-between tones. The RGB values corresponding to these densities were then found with a densitometer and used to plot the DLogRGB profile curve.
The “Create Profile” action extracts the curve's proportional variations from the calculated true negative and saves them as a small file that can be used to reconstruct the curve on any printer, irrespective of contrast.
The gradient used to prepare the profiles was printed on a Canon iP8760 printer using generic inks. The printer has one pigment black, a dye black and a grey cartridge, and yellow, magenta and cyan dye-based inks. The printer was corrected by a Photoshop curve to print the stepwedge with equal density differences.
The negative used to print the stepwedge was two negatives registered together and printed on Fixxons Waterproof Negative Film for Contact Printing. The paper was Hahnemühle Platinum Rag and the prints were exposed under a diffused LED UV light source.
Profiles for Argyritype, Classic Cyanotype, Kallitype, Salt and Van Dyke Brown are below.
Click on the button to download.
The Kallitype or Salt Profile should provide a starting point for carbon printing using Ammonium Dichromate, and the Kallitype Profile should be suitable for Platinum or Palladium.
Argyrotype
Exposure: 15 minutes.
Just White: Step: 46 / RGB 22.7 / Density: 0.05 / Paper White: 0.04
Just Black: Step: 110 / RGB 150 / Density: 1.07 / Dmax: 1.12
MidTone T9: 71.6 Graycard: (Density 0.8) 78.3
Step Range: 64
Comments
Disappointing Dmax. Attributed to having to filter a large amount of solids from chemistry.
Paper heavily coated with dry foam brush and 1.4 mL of chemistry (0.043 ml/Sq Inch) with three drops of Preen.
Air dried for 10 minutes, then for 20 min at 25 Deg C in drying cupboard at approx 30% humidity.
Classic Cyanotype
Exposure: 8 minutes.
Just White: Step 39 / RGB 18.4 / Density: 0.08 / Paper White: 0.07
Just Black: Step 116 / RGB 179 / Density: 1.31 / Dmax: 1.32
MidTone T9: 71.6 Graycard: (Density 0.8) 78.3
Step Range: 77
Comments
Paper heavily coated with dry foam brush and 1.4 mL of chemistry (0.043 ml/Sq Inch) with two drops of Preen.
Air dried for 10 minutes, then for 20 min at 25 Deg C in a drying cupboard at approx 30% humidity.
Kallitype
Exposure: 3 minutes.
Just White: Step 21 / RGB 10.8 / Density: 0.05 / Paper White: 0.03
Just Black: Step 106 / RGB 133/ Density: 1.27 / Dmax: 1.35
MidTone T9: 48.8 Graycard: (Density 0.8) 56.6
Step Range: 85
Comments
Paper heavily coated with dry foam brush and 1.4 mL of chemistry (0.043 ml/Sq Inch). No Preen
Processed in Sodium Acetate with 0.5 ml of 2.5% Dichromate.
Air dried for 10 minutes, then for 20 min at 25 Deg C in a drying cupboard at approx 30% humidity.
Salt
Exposure: 12 minutes.
Just White: Step 19 / RGB 10.2 / Density: 0.12 / Paper White: 0.09
Just Black: Step 119 / RGB 195 / Density: 1.27 / Dmax: 1.32
MidTone T9: 46.0 Graycard: (Density 0.8) 51.8
Step Range: 100
Comments
Paper heavily coated with dry foam brush and 1.4 mL each of salt and silver nitrate of chemistry (0.043 ml/Sq Inch). No Preen. Air dried for 5 minutes after Salt, 10 minutes at 25 Deg C in a drying cupboard at approx 30% humidity, followed by 5 miutes air dried after nitrate and 20 minutes in drying cabinet.
The Salt process was susceptible to staining; this was reasonably well controlled by presoaking the paper in a 2% salt and 1.5% citric acid solution and drying before use.
Van Dyke Brown
Exposure: 10 minutes.
Just White: Step 44/ RGB 21.4/ Density: 0.05 / Paper White: 0.04
Just Black: Step 116 / RGB 146 / Density: 1.30 / Dmax: 1.37
MidTone T9: 35.3 Graycard: (Density 0.8) 38.35
Step Range: 72
Comments
Paper heavily coated with dry foam brush and 1.4 mL of chemistry (0.043 ml/Sq Inch) with two drops of Preen.
Air dried for 10 minutes, then for 20 min at 25 Deg C in a drying cupboard at approx 30% humidity.
The short, high contrast toe in the highlights is clearly visible in the gradient, the curve reaching the T9 midtone only a quarter of the way along.