The Wet Collodion Negative - varnished and ready to run some test prints on Platinum Palladium and Rawlins Oil!
The Equation
Dmax: The area with the most density with detail.
Dmin: The area with the least amount of density with detail.
Subtract the Dmin from the Dmax and that is your NEGATIVE DENSITY.
The Print
If you want to maximize the quality of a print, you need to know what the Dmax/Dmin, or density of your negative is - maximum density (with detail), where the most silver is deposited. This is the brightest or highlight area(s). The thinnest part with detail is your Dmin area - approaching the void area or shadow(s). And everything else in between is the middle tones or middle values.
Why is it important? Not every negative will print well on every POP (Printing Out Process) or DOP (Developing Out Process). Some require density in the 2.0+ range - like Salt Paper. And some require less density. If you fail to match the negative with the process, it will never be as good of a print as possible if it were matched up.
In my opinion, you should choose a printing process and make negatives exclusively for that process. I’m not saying you can’t print a “Salt Negative” on Colodio-Chloride paper, you can. What I’m saying is that it will never be as good as a Salt print and vice versus.
My plans for this project are two types of prints. Both are “non-silver” and one is a pigment process. They are Platinum Palladium (mostly Palladium) and Rawlins Oil prints. I’ve made many Rawlins Oil prints and know that good negatives are almost identical to the Platinum Palladium process. The density of 1.50 - 1.80 is perfect. I can get great prints all the way to 2.0.
What happens if you don’t get the proper exposure or development on the negative? What can you do? Rarely are you too dense; I’m not talking about over-exposure, but getting in the density of 2.0+ with a foundation negative, or a negative straight out the camera. Most of the time they will be a bit under the desired density for technical reasons (fogging the shadow areas). If you need more density, you can do that chemically with pyrogallic acid and citric acid plus a bit of silver nitrate. This is called redevelopment and you can take it as far as you desire regarding density. Problem solved.
The Negative
Today, I varnished and prepared my test plate for my first run of the Platinum Palladium process and Rawlins Oil process. I checked the Dmax and found that where the light was hitting the back of the stump, my highlights, with details, ranging from 1.75 to 1.80. And the areas with the thinnest silver (some weeds in the foreground) that still had detail registered as 0.20 - that means if I subtract the Dmin from the Dmax I have a density of 1.59 - or thereabout. This should be a perfect negative for the processes. I’ll soon find out!