Cold Developer, does it still work?

[ciaran_mcmenemy]

<p>Hi! I will be fine-tuning my reversal process, firstly by under-developing slightly to leave more silver available for fogging (as opposed to being bleached out), and secondly by second-developing slowly or in increments, to achieve the best density. This can be done in theory with cold developer, since it would work slowly. But, will developer actually work at all below 20'C? Say, for 15'C.<br>

Ta!</p>

[peterbcarter]

<p>Cold developer will certainly work, but I am not sure you are using the best reasons to do so. It's not the bleach that is effecting your contrast, it would be the amount of silver solvent in your 1st developer. Reduce or eliminate that and you will get the maximum contrast. You will have to develop longer, but you will get the results you are looking for.</p>

[glen_h]

<p>Developer is Arrhenius. If you have two points on the time-temperature graph, you can use Arrhenius' formula to extrapolate to cold or warm. On the warm side, eventually the gelatin will soften up too much. On the cold side, it just takes a long time. (There might be other, nonlinear, effects that eventually come into play.)</p>

<p>The early films, maybe around 1920, used low temperature, as the gelatin wasn't as hard as modern films. But that gives very long times. Improved technology brought us harder gelatin, warmer (20C) development and reasonable times. Even with 20C as the recommended time, the tables went up to 24C or so. Ilford even publishes Arrhenius graphs, but the formula isn't that complicated. </p>

<p>But the tradition is that the actual image characteristics come from the first developer. The redevelopment, either color or black and white, goes, pretty much, to completion. That is, pretty much all developable silver halide is reduced to silver. That is why the time and temperature for first developer for color reversal films are so important. </p>

<p>You might try some cooler development of negatives to get used to the effect.</p>

[ciaran_mcmenemy]

<p>Thanks! I developed a few reversals and there are some black (well, dark because of too much silver) even though I made proper exposures, so I figure it would be easier to underdevelop slightly to give myself some silver to work with (i.e. can go from quite clear to quite dark). Developing to completion isn't too reliable, ... so I will do what I just said then cold develop it for say 20-30 sec, wash it, check it, if there are a few frames not dark yet I can dip them in, the rest get fixed. Etc. </p>

[peterbcarter]

<p>You may even have bleach falure. What type of bleach are you using?</p>

[ciaran_mcmenemy]

<p>Thanks for that equation. On the development chart there is a time/temperature calculator, is that how they do it?</p>

[glen_h]

<p>The charts should be Arrhenius, with 1/(absolute temperature) on one axis. For the temperature range normally used, 1/T is close enough to linear that they often use a linear approximation. </p>

<p>From 20C to 30C, the absolute temperature is from 293K to 303K, not a big relative change.</p>

<p>If you see a graph, that is how it is done. In the charts, they often round to the nearest half minute. If you fit all the given points, it should be pretty close. If you just choose two points, maybe not so close.</p>

[neil_grant]

<p>Lower tempertures reduce activity of developer - so it takes longer to produce a given effect. If you drop temp much below 15C then activity can reduce drastically. The first dev in an E6 process is quite 'foggy' by design so as to produce clean highlights in the reversed image. I believe in a b/w process a little thiosulphate may be used to reduce the tendancy of 'reversals' to get too dense. Not sure why dev to completion should cause any special problem.</p>

[ciaran_mcmenemy]

<p>hello! my bleach i just a 2% H2SO4 and 2g/L KMnO4 solution. Actually, I don't know how to measure such a small amount in grams, so I use a little bit from a teaspoon. anyone have a better approximation?<br>

The images I got were sometimes quite 'black' overall so maybe I should try that. Can I re-use the developer after though if it contains fixing solution/crystals? I'm guessing it would give a slight overall reduction in density.<br>

The Arrhenius equation is k = Ae^-(Ea)/RT , is there a way to work out volumes with this? Like if I wanted to use 1+19 Ilfosol 3, say. (Incidentally I bought Fotospeed FD10, same dilutions as I-3, only ~£8 (10 to 11 dollar/euro) for 1L concentrate. I think it might be the cheapest liquid developer there is) </p>

[peterbcarter]

<p>The first developer needs to be quite strong, which is why paper developers are usually used. You are developing much more silver than a negative. It's pretty much useless after being used once.</p>

<p>The bleach is stable when mixed with water and kept separate acid / oxidizer (permanganate or dichromate) I use 2l bottles and find it's much easier to measure 24g of dichromate for a 2l solution. I just mix 50/50 of acid/oxidizer at bleach time.</p>

<p>The second developer should never use discarded 1st developer because the silver solvent(s) are in it and the 1st developer is not active enough when used once.</p>

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[ciaran_mcmenemy]

<p>So is a paper dev just more stronger than a film dev? I some Fotostop CI(?) chromium intensifier, and it says to use a paper dev. I keep my acid and oxidiser separate - the ox. is potassium permanganate, a lovely purple colour. Afer bleaching, is the solution rendered ineffective for further use? <br>

Oh well, maybe I should use a clean second dev solution.<br>

Some strange things happened today. I have done two reversals.: the first things is that there were bad surge marks, even though I agitate regular (cont.30 sec, x3 every 30 sec, tap x3 after each). secondly, I redeveloped and the positives looked fine, so I fixed them. After fixing much of the image was lost. Why would that be? Is it a bad idea to fix after second development? Info: HP5 Plus 400 and Lucky SHD 100 as 400. Initial development was as if for the negatives. Bleach 5 min constant agitation. Clearing (that stuff smells funny... I don't trust sodium meta!).Redevelopment in Ilfosol-3.</p>

[peterbcarter]

<p>It tends to be a higher concentration as paper is only about 2-6 iso. I use Dektol 1:1 and that works well for me.</p>

<p>I use dichromate and I can get about 10 rolls out of 200ml of working solution. My drum only uses 150 ml. I hear permanganate is slightly shorter lasting, but I don't know. I have used working solution that was up to 2 days old, but again I am under the impression that dichromate lasts longer.</p>

<p>On the errors, it sounds like you were not developing to completion. I don't think ilfosol-3 is strong enough. Dektol is pretty cheap.</p>

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