wow, this sounds mind-bogglingly of interest - then presumably you can bleach-tone film positives as well as negatives? i'd like to shoot some Kodak Tri or Plus-X Super 8 film and part-tone it after development, just to see what would happen?
Hi Ric,
As long as they are silver based positives, yes you can. Indeed if you are doing it for projection, you could also consider using the metal based toners like, iron-blue, copper (which can give a range of colours in the red, brown, purple range; depending upon emulsion and chemistry), various green and yellow toners.
This would definitely require some experimentation, as some of the toners can give weak colouration, which may not show when projected (yellow is a likely culprit for this). These toners are also not archival, and will be prone to bleaching if projected a lot. The archival toners - selenium, sepia, (poly-)sulphide, and gold will be more stable to projection.
BTW Gold toning can give nice blues on warmtone papers, it would be an interesting experiment to see what you could get from bleach/redevelopment and gold toning on film positives.
If you were going to split tone using a mixture of archival, and non-archival toners, use the archival ones first, but for a short time so thay just affect a controlled range of the image tone. Then use the non-archival toners.
I would recommend picking up a copy of Tim Rudmans book "
The Master Photographer's Toning Book", as the possibilities are tremendous.