Pl 3: KI only (1g/100ml of collodion)
More contrasty image; sensivity in highlight equal to pl 2 but loosen midtones and red / yellow.
The lack of bromide makes the difference
I Introduced KBr (dissolved in a few drops of water) in the KI only recipe used for pl 3.
No precipitate untill I added some ether
Idem plate 5 but after adding some ether which induced a light precipitate
Another advantage is that it seems bromide sharpen the image, because all the images taken with KI only show a sort of blur as if the camera or the subject had moved slightly vertically visible especially on high lights "drool"
Shots were performed without any modification of the device (framing, focus, lens)
and I alternated different recipes.
I will not speculate on this but it may be about chimical focus phenomenon...
When diluting Old guy with same volume of collodion+alcool (=half amount of salts) we obtain the same improvement (same exposure, same developement on the next two plates)
Ceci correspond aux proportions et quantités de sels données par Monckhoven pour qui un collodion pour positif direct est environ deux fois moins salé qu'un collodion pour négatif.
Voilà quelques pistes.
This is matching with collodion recipes given for positives by Monckhoven which are about twice less salted than negative's formulas.
Here're some clues to try.