Quote Originally Posted by gainer
When you use ethylene or propylene glycol or glycerine as solvent you must add alkali to the working solution. There are many possibilities.
I used a 0.5 % sodium Carbonate solution.


You zeroed your densitometer on B+F, so the Zones that measured 0.4 surely can't be fog. They can oly be a mystery!
That's why I asked. I don't understand it either. If it's my Nikon F4 exposing for more than zone 0, I don't understand why this base density stays the same from zone 0 to zone III. And that on several different films. I will try another brand of ethylene glycol too. Maybe in this one there are additives influencing film development.


Try using 1 tsp each of sodium carbonate and borax in a liter of water to dilute your glycol solution 1+50 for a quick and dirty test. This should give you a fairly linear plot from zones 2 on up with development of about 8 minutes at 70 F. If actual fog is too high for you, add some bromide to the working solution. I am not overly concerned about the fog I have seen, but if you use some of the alternative processes as Sandy does, double fog density means doubling an already very long exposure to UV light.
I'm not overly concerned about fog either. But I don't like the curve to start rising only at zone III or even more. An EI of two stops less is a PITA.

I guess I'm going to test the whole thing again with another camera, another brand of antifreeze, and bromide (one change at a time ofcourse). Restrictions on selling chemicals are very strickt here in Holland, so I cannot easily get chemical grade glycol or TEA. (I'm still looking for the Oil of Olaz variety of TEA )

Gilbert