[Kallitype] Ammonium Dichromate won't mix/is streaking

Andrew O'Neill said:

Start with a 1% solution. Add a drop and see what happens. It's always best to tailor your negatives to the process so you don't have to rely on contrasting agents.

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fgorga said:

I am a bit confused by your use of terms. You say that you are using 5% ammonium dichromate which implies that you have a solution. Is this so? Do you have a bottle with a single phase... i.e liquid and no solid at the bottom? You should as the solubility of ammonium dichromate in water near room temperature is roughly 35%.

You go on to say that the ammonium dichromate will not dissolve in your sensitizer. Do you really mean that the two solutions won't mix together? How are you mixing them after you add them together? You might need to actually stir them together with a glass rod rather than simply swirling them together wich is not a particularly effective way of mixing things.

I agree with Andrew... it is best to have a negative than does not require the use of dichromate to increase contrast.

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MatthewDunn said:

I am probably (almost certainly) mis-using terms.

In essence, when I attempt to mix a single drop of the 5% Ammonium Dichromate solution with the Silver Nitrate and Ferric Oxalate, I get something that looks like oil and water - the contrast agent simply won't "mix" with the other two, regardless of how you try to swirl it, etc. No precipitate, nothing formed, just oil and water-like.

Edit: Yep, I am mixing them in a heavy shotglass and stirring with a glass chemical rod.

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Andrew O'Neill said:

That's really weird Matthew. It always went into the sensitiser with ease for me... especially with such a tiny amount, too. Do you have any Kodak Rapid Selenium Toner? Maybe you could get a contrast increase by giving the negative a bath in 1+3 solution. Of course, you should practice on a negative you don't care too much about, but has the same (ish) density range...and the get a decent result, the negative should have a reasonable amount of density to begin with... if it prints well on grade 2 silver gelatine paper, for example. I've always been able to get equivalent to N+1 expansion.

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MatthewDunn said:

I have Ilford Selenium Toner.

I really think you nailed it on the head in your first response, which is to say that I don't think (and I can't believe this) that my negatives are sufficiently dense. I don't have access to a densitometer and have never silver-printed these, so I can't tell you what grade they would come close to. I printed this again tonight with a reduced exposure time and no contrast agent. I am still getting a pure black rebate, but the contrast just isn't there, which suggests to me that I simply don't have the requisite density in my negatives.

I have been sticking to the rough estimate of 1.5x normal processing for alt-processing, which for FP4+ in Pyro-HD is ~10-11 mins. I have been doing 10 mins, but I think the first thing to check is to develop a negative at 15 mins and one at 20 mins and print those both to see if minimum black is accompanied by better contrast.

As you can tell, I have a very limited sense of what I am doing. I am enjoying experimenting, but am hoping to dial this in. Not a tinkerer for the sake of tinkering like most here.

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Andrew O'Neill said:

I like to make a ring-around using four negatives developed for different times. Print them all for your chosen kallitype print time. Hopefully you can then nail correct development time. FP4 and Pyrocat-HD are well suited for alt processes.

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MatthewDunn said:

I could certainly do that.

I was initially planning on following the method described in Ian Leake's Platinum Printing book, which uses test strips across a single image to find the first time at which the film rebate reaches black (i.e. is indistinguishable from the surrounding, leftover emulsion. My assumption was that, once I have the time for minimum black, if I am not satisfied with the contrast, I just need to continue to add density to the negative until I am satisfied.

I think we are saying essentially the same thing. I am including the time to find the proper "exposure time" and would have then printed negatives one by one, but the ring does the same thing in one-shot fashion.

Unless you think otherwise, will proceed in this fashion.

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Andrew O'Neill said:

Yes, the maximum black/minimum time should be the first test one does. Then I use that time for a ring-around.

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MatthewDunn said:

Because, to be clear, the max black/min time can be done with any processing time, correct? In other words, we are just checking when the film rebate (i.e. B+F) goes to black, and B+F should always be the same density (independent of processing time). Whether I developed a piece of FP4+ in Pyro-HD for 10 mins or 20 mins, I would expect the rebate to look the same.

So, perhaps process an unexposed piece of film and use that with my test strips to find min time? Then on to the ring?

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Andrew O'Neill said:

I teach my students to do a min time max black for making 35mm film contacts on RC paper. Since there is some build up of B+F with the 20 min dev time compared to the 10 minute time (depending on film used), the resulting print would be a bit lighter if you used the min time for the 10 min developed film. You'll most likely have to do a min time/max black test for the 20 min developed film.

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MatthewDunn said:

OK. 4x5 processed normally (other than for time) for 20 mins drying. Will report back as soon as I have more details. Thanks, Andrew. A million thanks.

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Andrew O'Neill said:

I would go with 60 seconds. I wish my exposures were that short!

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Andrew O'Neill said:

You can contact the step wedge directly onto your film. The 31 is same size as 4x5 film.

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MatthewDunn said:

I see what you are saying. That actually seems like something that would be good to have - a set of 4 4x5 negatives of various densities. Assuming you are more or less content to stick to one film, you could probably go from process to process and make life significantly easier by just throwing the 4 negatives down on a sheet and cooking for minimum black time.

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Andrew O'Neill said:

One film and don't change the developer. I think it would save one time and definitely, materials.

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MatthewDunn said:

I have Ilford Selenium Toner.
...
I have been sticking to the rough estimate of 1.5x normal processing for alt-processing, which for FP4+ in Pyro-HD is ~10-11 mins. I have been doing 10 mins, but I think the first thing to check is to develop a negative at 15 mins and one at 20 mins and print those both to see if minimum black is accompanied by better contrast...

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