Got questions about b&w reversal process
This is my first experience with the b&w reversal process. I am trying to process some older 7262 plus-x reversal film. The film is too dark. I'm using mostly home brew
chemicals, which is problematic in itself. The problem I'm am having is that
the film is underexposed and I'm not sure what to push or pull. The first dev or second. Below is an old list posted by who I'm not sure. I'm sort of patterning
my process after this.
1.) First developer - D-76 1:1 - 9:30 @ 68F
2.) Stop Bath - Acid Stop - 00:30 (not using this step)
3.) Wash - Running water, 2 fill & dumps of tank
4.) Bleach - Sodium dichromate bleach - 2:30
5.) Wash - Fill and dump tank for about 5 minutes, until water is not orange.
6.) Clear - Kodak Hypo Clear - Two minutes with inversion.
7.) Re-Expose, 60 watt room light, 1:30.
8.) Second developer - D-76 - 7:00 @ 68F
9.) Stop, fix, wash as normal.
7.) Wash - Running water, 2 fill & dumps of tank.
Anyway maybe some kind soul can look this over and give me some
suggestions. I'm not sure why the first developer is diluted.
Any help will be appreciated.
Last edited by cinejerk; 05-07-2009 at 09:21 AM. Click to view previous post history.
The reason why your film looks too dark is because regular D-76 1:1 is not a suitable first developer for reversal processes.
The role of the first developer in B&W reversal is to develop the "negative image" into metallic Ag, leaving the "positive image" in AgX form. With normal exposure, regular developers like D-76 leave a lot of undeveloped AgX left over, which results in overly dark positives if they're used in reversal processes (all that leftover AgX forms the silver in the final slide). You can get around this to some extent by massively overexposing the film, but even then, there is always leftover unexposed or undeveloped AgX that turns into Ag after the second development and creates a dark fog or haze in the image.
To get around this problem, first developers for B&W reversal need to have high activity -- much higher than what is usually found in a B&W film developer. D-76 1:1 or even D-76 straight are not enough. Typically, reversal developers look more like paper developers than film developers. If you look at Ilford's PDF file on reversal processing, they actually provide a formulation for a reversal first developer that's based on Bromophen paper developer.
In addition, first developers pretty much always contain a silver halide solvent like sodium thiosulfate or potassium thiocyanate. These ingredients essentially provide a bit of fixer-like action during developing, clearing out traces of AgX that simply can't be developed by even the most active developer. Leaving out the silver solvent typically makes the finished positives look "dark" overall -- areas that should be light (sky, white objects, etc.) have too much density.
My suggestion would be to look at the Ilford reversal-processing PDF and use the process they recommend. You'll have far more luck with that than you will with D-76 as a first developer.
D-19 or D-8 are often used as the first developer, with about 0.5 - 1.0 g/l KSCN or NaSCN as Jorday says.
Thanks Jordan and PE. I have a lot of D-76 so what can I add to it to make it more active? sodium hydroxide?
PE I'm not a chemist so please spell out KSCN and NaSCN thanks. I know it's sodium and potassium something ;-)
KSCN = Potassium Thiocyanate, NaSCN = Sodium Thiocyanate.
Making the D76 more alkaline with NaOH (Sodium Hydroxide) will probably work, but you have to do it in a repeatable manner for the future work you may do. If you want to do something like this, you should get the materials needed rather than improvise.
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Ok here are some formulae to make 1ltr
sodium sulfite 90gm
sodium carb 52gm
potassium bromide 5gm
sodium sulfite 90gm
sodium hydroxide 37.5gm
potassium bromide 30gm
What makes them more suitable?
Carbonate vs Borate gives a much higher pH and buffer capacity, which gives better first development. Sodium Hydroxide also increases pH for higher contrast. I'm not sure that the HQ level in D8 is correct. I assume that is the reason for the "?". I do not have the formula handy.
Yea, I don't know about that amount of hydroquinone either. I'm getting these out of an old(1955)handbook of chemistry & physics.
sodium sulfite 100gm
Give me a ball park amount of lye to add to this.
That's the correct level of Hydroquinone in D8 and Bromide
D8 is a high contrast developer, D19 would be more suitable, it becomes D67 when you add Thiocyante, this is Kodak data for Reversal processing.