Reversal Bleach, help!

[ciaran_mcmenemy]

<p>Hi! Today I tried reversal on Fomapan 100, which I pushed to 800. I figured that pushing would increase the contrast, which is a good thing for a slide. I followed the Ilford reversal guide, but I'm having a problem with the bleach.<br>

I mixed a 2% strength solution of H2SO4 for 750ml total (the guide says concentrated acid 10 ml into 490ml water, or 100ml 10% acid into 400ml water; both are equivalent to 2% strength). In a separate jug I added about a gram of potassium permanganate powder (it's a lovely purple colour!) into what would become a 1L solution. I combined 250ml of each solution, but after using it I can still see silver, mainly the sky part of photos. Why hasn't it disappeared?! I'm expecting it to look milky and vague/blank. I agitated it with the stick, quite vigorously..</p>

[ciaran_mcmenemy]

Update- it was bleached for over

40 min. I decided to use clearer,

and the film was perfectly

clear... Oh! Nothing left!

Does that mean bleach will take

ALL the silver if longer than 5

or so min?

[peterbcarter]

<p>Yes. If you under expose your film, you need to develop (much) longer. You are mistaken if you think you need to bleach more. If your leader is clear, there is enough bleaching going on.</p>

<p>If you just want more contrast, develop more and use less (or none) silver solvent. I develop Foma 100 in Dektol (1:1) with no silver solvent.</p>

<p>Foma 100, reversal</p>

<p><img src="https://c2.staticflickr.com/6/5034/6950440554_9bcd00ccd8_z_d.jpg" alt="" /></p>

[ciaran_mcmenemy]

Hi! Can you tell me how you

bleached it? What agitation?

Oh, I did compensate for that in

development. Not like I'd expise

at 800 and develop as 100 :/\

 

Great detail. Did you add fixer

to the first the first dev?

 

After 5 min I checked and could

still see the images, I thought

they were supposed to be blank...

Is it the clearer that makes them

really blank?

[ciaran_mcmenemy]

No matter now, I tried again.

Looks good! I'm surprised, I

thought I could still see the

silver of the sky after

bleaching; but it turned out well

[ciaran_mcmenemy]

<div></div>

[peterbcarter]

<p>They do look good. Congrats.</p>

<p>FYI: In reversal, the bleach removes the developed portion of the film. Generally if the leader of your film (35mm) is clear, it has done it's job. If left too long, it will start to desolve the rest as well. It is not as dramatic as developing, but it cannot compensate for under exposure.</p>

<p>I bleach from about 4-8 mins, depending how old my mix is. I use dichromate bleach which lasts much longer than yours.</p>

[ciaran_mcmenemy]

<p>Thanks!<br>

what are the bleach chemicals you use? great advice, I will make sure to check the leader from now on.<br>

I have a question - do you fix after the second development and subsequent wash?<br>

I noticed little clear specks on my positive, I don't remember seeing them before. </p>

[peterbcarter]

<p>I use potassium dichromate/sulphuric acid for the bleach.</p>

<p>To confuse you, sometimes I fix and sometimes I don't.</p>

<p>If I am using a traditional flashing with a light bulb, I fix. I do this because I don't want any surprises down the road. There is not guarantee that the second development has actually been developed to completion.</p>

<p>When I use a chemical flash, I don't fix. I have tested this and I can reliably trust this.<br>

</p>

 

[ciaran_mcmenemy]

<p>ah, thanks for the info. what would happen if you didn't fix after traditional re-development? is there the possibility that the image will get darker?<br>

What's the advantage of dichromate instead of permanganate?</p>

[peterbcarter]

<p>Yes, it can get darker over time. You can easily test buy sacrificing a frame from you developed film and sticking it in the window for about 6 months. If there is anything to worry about, it will get dark. You can fix at any time, but it will not undo any darkening that has already occurred. I fix anyway because it does not use up the fixer and is only 5 mins out of my life.</p>

<p>I use a dichromate bleach because it is what I *can* get. At the end of the day, I don't think there is really much difference except the mixed solution lasts just a little longer.</p>

[chris_waller]

<p>I make bleach using 100 gm pot. ferricyanide and 100 gm pot. bromide made up to 1 litre with water. That's very concentrated so you might want to dilute it to make a working solution.</p>

[peterbcarter]

<p>That's not a reversal bleach. A reversal bleach ONLY bleaches the developed areas. The bleach you made bleaches all silver and puts it back to it's pre-exposed state.</p>

[ciaran_mcmenemy]

<p>maybe this sounds silly, but if you don't fix film is it possible for it to develop little holes? I tried skipping the fixer on a test frame, and later noticed it had damage. Not sure why! Does hypo just remove the unused silver, or does it 'stabilise' the used silver and make it last longer, in some way?<br>

Thanks Chris. PoFerro sounds dangerous, I'm surprised to read it's not. It's useful to know how to halogenising chemistry! What's your dilution?</p>

[ciaran_mcmenemy]

<p>I know this sounds pointless, but from an experimental point of view; say you have a negative (or positive) and you used halogenising bleach (without fixer) on it, until the image disappeared. If you were to re-expose it to light and re-develop it, would there be any major changes?</p>

[peterbcarter]

<p>The fix just removes the undeveloped silver.</p>

<p>As far as holes, that can be damage by the bleach potentially lifting the gel (what contains the silver). I mix my bleach half strength and let it go twice as long when using a film that suffers from this. It's important that you do not squeegee reversal films as the emulsion is delicate until it dries. </p>

[peterbcarter]

<p>If you used the suggested bleach, your image would be completely removed and your film would come out black. After that bleach you can re-expose the film and have a completely different image on it, as you have effectively erased it.</p>

<p>Those kinds of bleaches are used in C41 where the silver is not actually used for the image. The silver is developed with the dyes attached. Once the dyes are developed to an image, all the silver needs to be removed.</p>

[chris_waller]

<p>Ciaran, hi.<br>

<br />For bleaching prints prior to sepia toning I use it at full strength. It takes about a minute of constant agitation to bleach the print. Note that the image doe not completely disappear, it fades until it is very pale. For split toning I use it diluted 1/50 or even 1/100 so that it very slowly bleaches just the highlights. Then I wash it, sepia tone it, wash it again then selenium tone it.<br>

For film I use it again at full strength. I used it in the photo-pointillism process with colour film prior to redevelopment in C41.</p>

[ciaran_mcmenemy]

<p>Oh, the bleach <em>can</em> damage it... I never squeegee! Is photoflo any good? <br />(C41 stabiliser is terrible when it comes to leaving clean negatives, there are streaks everywhere...)<br /><br />I was thinking of trying reversal on print film. The B&W reversal didn't work - I bleached/cleared it and I could see a negative image and a sort of fog underneath, but not on the sprocket area. .. So next time I will develop the black and white, expose it to light, then carry out the C41 process. Might be a cheap(er) way of doing slide film!<br>

Can the clearing solution (sodium meta in my case) be reused? The PDF is unclear.<br>

Thanks for your reply Chris. I wondered how toning works! What chemical(s) are used to tone the film itself? Is the element/molecule you replace silver with stable as well?</p>

[peterbcarter]

<p>Photoflo is fine on the very last step, as you would any other film.</p>

<p>You can reverse any silver nitrate based film or paper. Not all films are great, but you will always be able to do it. The thinner the emulsion, the easier it is.</p>

<p>Sulfuric acid is by far the best. But 25g of Sodium (Meta)Bisulphite in 1l should be adequate for this use. This substitute does break down fairly quickly. If you are not going to use the litre in a couple of months, make less.</p>

<p>The clear will slowly turn green as it get's used up. It will usually outlast your dichromate/permanganate/sulfruic acid bath. Washing well between these two baths will make this last longer.</p>

<p> </p>

[ciaran_mcmenemy]

<p>Thanks again Peter! so I should wait for it to turn green.. it's a little bit milky right now. I tried BW reversal on a colour film, and it didn't work. After bleaching, I could see some sort of fog (just not on the sprockets) under the negative images. I'm guessing it's the filters built into the film..?<br>

Any idea how to accurately measure out 2g of some powdered chemical? I don't think scales are sensitive enough.</p>