Quote Originally Posted by Photo Engineer View Post
It is impossible to predict. ...
PE
First, I should have said thank you for that response. I'm not a chemist so I had no idea at all, but that answer was not "futility", so I was encouraged to explore further. After tonight's work, I am greatly encouraged and think this might work, but still need to do a lot more testing.

You are absolutely correct: a simple test was all that was needed. The answer is "yes", and that fixing is a further consideration. By reducing the concentration of sodium carbonate, or adding sodium bicarbonate, the effect is reduced and it happens in a very systematic and controllable way.

I started a little further back in my tests tonight, just to be sure:

1) No effect whatsoever in plain water. ( had to check )
2) No effect in water with increasing amounts of sodium bicarbonate.
2a) Left to explore further and very intriguing: test strips that went into the bicarbonate solution would not develop later even in strong sodium carbonate solution. It has "disabled" the active agent.
3) Dark grey as observed yesterday with 1/4 t "washing soda" per 2oz water. Several tests confirmed that the tone changes with concentration of sodium carbonate. I don't know enough about this but I think the ph will max out as the solution gets saturated, but I don't know where that point would be, and for what I'm doing it doesn't matter: I'm trying to reduce the effect. ( I'm not assuming this is ph, but it is related to concentration. )
4) Lighter grey after adding 1/4 t bicarbonate
5, 6, 7...) each addition of 1/4 t made the grey lighter, by an amount that was very noticeable and looks a lot like a step card.. it is easy to judge. I did not time the reaction carefully, but my impression was that it did not take longer. All of these tests ended after about 15 or 20 seconds with no further "development". Presumably the agent was exhausted.

Now things get a little interesting when I tried fixing the test strips ( after wash )

I got various shades of tan and brown in the "lighter versions". Most of the grey bleaches right away in the fixer ( doe this mean that it is not reduced silver? ) The darkest ones still retained some grey ( so I think that means there really is silver and this isn't all about dyes or staining. ) The very darkest ones look like a flat somewhat underexposed print. The darker ones have an unpleasant drab greenish tinge to them.

These were strips from a lumen print and some of the intermediate ones fixed to a light chocolate color with hints of pink in the highlights. Some have hints of yellow in the light brown.

Now very interesting:

In the same intermediate ones, contrast increased dramatically in fixing and especially during dry-down. I could actually see details emerge and subtle color shifts as it dried. I have the impression that there is a "sweet spot" that will maximize contrast and have nice colors. I have one snippet that I think might contain *more* detail than the original lumen print ( but the contrast is low. )

The fixed images from two hours ago have been sitting directly under a fluorescent lamp since and have not changed. I think the images are fixed but I need to test that idea by leaving them out longer.

I've got quite a lot more I want to test but this is pretty fun.

-Ned