Hoo boy, are there a load of answers to those questions. The basic idea is that you need to determine a curve that translates the sensitivity curve of your original process to that of the printing process of choice. There are several different ways to do this. The way I use is a simple approach that I learned from a workshop at the George Eastman museum: the basic steps are:
1. inkjet print a step wedge on the transparency material you intend to use
2. scan the result with a scanner
3. using Photoshop to average the values in each area of the step wedge
4. use the eyedropper to get that average value
5. use the values to make a curve
6. apply the curve to your image before inverting it
7. print the inverted (and flipped!) image to run it through your printing process, cyanotype in this case.
The result is a cyanotype of the step wedge, which you can then run through the process again to get closer to linear. Once you're satisfied with the results, you save the curve as a preset, and apply it whenever you want to print something using that transparency material and that process. I have saved presets for salt and cyanotype, and just use the salt preset for albumen printing as well.
It sounds more complicated than it is in practice, and I've found it works well. Here is a salt print I did using an image I took with my little Sigma DP2 some years ago:
salt-001, First salt print, Salisbury Cathedral, 2009 by
Robert Brazile, on Flickr
There are refinements you can do for alternative processes such as cyanotype, salt, and carbon, for example, you can print out an inkjet color gamut and run through the process to discover which of your inkjet inks blocks UV light the best. But this isn't strictly necessary, the blacks work just fine in my experience. I did do this once, and the best of my ink set was a sort of dark green, but it was a very marginal difference.
As I mentioned, there are several methods out there to do this, which use different applications and refinements to get to the same general process outlined above. One is Ron Reeder's; he had a published book to do this which you may be able to find used, or you can buy his self-published editions here:
http://www.ronreeder.com/qtr-digital-ne ... loads.html
If you want a more explicit set of instructions and software for helping create the curve, you can look at something like Mark Nelson's Precision Digital Negative system, an e-book plus software, which can be seen at:
https://www.precisiondigitalnegatives.com/about.html.
One caveat: you need something like Photoshop to do this. I have been using Photoshop, but the last MacOS update killed mine, and I've so far refused to submit to the subscription service. I'm trying out Affinity at the moment, which I believe will work, but I haven't gotten to trying this particular process using it yet.
I hope you try it, I think you will enjoy it. Let me know if you have further questions.
Robert
