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holmburgers · Jul 15, 2010

Hi y'all,

Ok, looking to do some reversal processing; starting out on 4x5" sheets of Delta 100 in a tray. I've compiled a list of what I think I need to get using a few different sources, such as the Ilford procedure and this one... http://silent1.home.netcom.com/Photography/Dilutions and Times.html#BW_Reversal and some various posts on APUG.

I'd just like to get input from you wizards here and see what you think; there are many formulas so if my decisions seem arbitrary, they probably are.

1st Developer
Dektol 2+1
Sodium Thiosulfate 8 g/L
?? Should I use potassium bromide as a restrainer ??

Bleach
Potassium dichromate 10 g/L (chosen over K-permanganate for its non-softening reputation as well as it's more stable, as in I don't have to mix it immediately before use(?))
Sulfuric acid (can I buy battery acid at a NAPA and get by with that?)

Clearing Bath
Sodium Sulfite 100 g/L
*now, Ilford says Sodium or Potassium metabisulfite... is this the same thing?, Na or P?

2nd Developer
D-76 2+1 (this is based off of the HC-110 recommendation, and I tried to pick an analogous dilution... however I wouldn't be against buying some HC-110 if it's preferable)

Fixer, HCA
Kodak Fixer, just to be safe, and how about Kodak HCA, any reason to do so?

Thanks in advance for your input

Jordan · Jul 15, 2010

You generally follow a dichromate bleach with a sulfite clearing bath, and a permanganate bleach with a metabisulfite clearing bath. There are chemical reasons for this, but it's been a long day ...

Your solutions sound fine. Give it a try and be careful with the dichromate and acid. Be prepared to run a lot of experiments to fine-tune times and temperatures.

hrst · Jul 15, 2010

And fine-tune sodium thiosulfate level in first developer. Higher level gives brighter picture and clearer highlights but too much is too much. That level destroyed the whole image with APX100 leaving blank film so there is much variation film-to-film. IMO better start too low (or at zero), you just get a bit muddy highlights but it's easier to crank up there. Just IMHO.

holmburgers · Jul 15, 2010

Jordan, thanks for the heads up. I'll see if I can't find the reason for this sequence myself, but that definitely makes my decision easier

hrst, I'll follow your advise on the sodium thiosulfate.. going low & slow. I'm not sure I fully understand it's purpose in the 1st developer, however.

hrst · Jul 16, 2010

holmburgers said:
I'm not sure I fully understand it's purpose in the 1st developer, however.

The point is to eat away some halides, just like in fixer, but the level is kept so low that it doesn't eat all the image away. It works differently on shadows and highlights, thus giving an increase in contrast by clearing highlights. I'm sure someone can explain this more in detail.

It's easier to interpolate than extrapolate, so you might consider doing two extremes, one at zero level and other at Ilford level or even a bit more.

holmburgers · Jul 16, 2010

I'll start with a conservative level of hypo, like a bit less than ilford says and go either way from there.

By 2+1 I guess I mean 2:1 (not good with the nomenclature), or, two parts developer and one part water.

Nope, no toner of any sort and I have not seen "the Day after". Why??

I'll be careful, thanks guys!

Oh, and about the hypo in the 1st developer.... it is eating away the unexposed halides, right? That is to say, working on the positive image?

holmburgers · Jul 16, 2010

OHHHH, that movie!

Believe it or not, I haven't watched it. Sacrilege, right? I should probably see it....

I do know about it though, I just didn't recognize the name. A lot of it was filmed on the University of Kansas' campus, where I went to school.

holmburgers · Jul 16, 2010

on behalf of Kansas, thank you!

holmburgers · Jul 19, 2010

Does 100 grams of sodium sulfite seem like a lot?

Ilford says 25 grams of ___*metabisulfite*, but it's a different chem so who knows. Just wanted to make sure it's not a typo, but I guess I'll be getting a pound of that... YIKES.

Ian Grant · Jul 19, 2010

The Metabisulphite is need with Permanganate, as per the Ilford formula, nut only Sulphite is needed with Dichromate,

Metabisulphite contains free SO2 and is quite acidic in solution while 100g/litre Sodium Sulphite is alkaline and doesn't remove permanganate stain. It's the most used of all photo-chemicals and cheap so buy as much as you can.

Ian

holmburgers · Jul 19, 2010

so in otherwords, proceed as I was?

Thanks!

Ian Grant · Jul 19, 2010

holmburgers said:
so in otherwords, proceed as I was?

Thanks!

Yes, and remember Sodium Sulphite is in Developers, Fixers and Was aid so rather useful

Ian

holmburgers · Jul 19, 2010

good to know. I should have plenty!

holmburgers · Jul 21, 2010

What precautions should one take to do reversal processing in trays for 4x5" film. Playing around with sulfuric acid in the dark sounds fun, but perhaps a tad dangerous, no?

Latex gloves aren't robust enough, right? Nitrile then? This seems like a serious tactility concern.
Glasses - check, apron - check.

After the 2nd/fogging exposure, can I carry out the rest of the process in room light? I suppose this would simply things somewhat.

Can I expect to be able to process 4+ sheets at a time or should I stick with one?

Any tips would be welcome. Thanks!

Jordan · Jul 24, 2010

Alessandro Serrao said:
Is it the purpose of metabisulfite to reduce MnO4- to MnO2??
So if it is that way, any chemical that undergo oxidation (including sodium sulfite) should be fine, or am I missing something?

I am not up on this chemistry, but in general you want the permanganate to be reduced all the way down to Mn2+. MnO2 in the film would be bad news. Metabisulfite solutions are acidic and this acid environment is probably required to complete the reduction of MnO2. Again, just a guess, as I don't have my references handy.

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