Stop Bath with Hardener

[mrred]

I need to introduce some hardening before I bleach (bw reversal) and I have read that some do this. Is it simply a case of adding som chrome alum to the stop?

 

[holmburgers]

Out of curiousity, why do you need to add hardening? Are you having trouble with the emulsion?

I'll be curious to see what others say, but I'm not sure if I've ever heard of anyone doing this, but that's not to say...

 

[Mike Wilde]

I have in past experimentation used a hardening solution as a separate step from the stop bath.

I am pretty sure it came out of 'the darkroom cookbook', and likely used potassium alum as a major ingredient; I don't think I had any formalin in stock at the time I was working with hardeners, and recall that raided the pickle making area of our spice shelf in the kitchen to make it up. I am replying from work, so my notebooks on the efforts are not close at hand.

I did not combine it with the stop bath, as I was unsure of the stop bath acidity on the effectiveness of the hardening agents.

I think I was doing a bleach and redevelop, and the bleach was a pretty strong on sulphuric acid, so I wanted to toughen the gelatin layer up before it saw the acid bleach.

 

[Photo Engineer]

Going into an alum stop after development will cause precipitation of the aluminum as the hydroxide and hardening power will be reduced. It would be best to preharden the film using formalin or chrome alum. If you use chrome alum after development, there should be a wash before and after the hardening step.

PE

 

[Rick A]

I've read on another site to harden in the presoak, then develope. Sounds like what PE just said.

 

[mrred]

PE, I have seen places where they use hardener in the stop. I was under the impression that it was simpler to implement. I was thinking that I need the emulsion harder for the more bleach than the developing. I'm open to anything to keep the emulsion from falling off; pre or stop doesn't matter.

Suggestions for a simple and obtainable formula would be an advantage, as I am in Canada and getting some ingredients across the border can be a bit nuts. I can get chrome alum fairly easily.

 

[Photo Engineer]

A hardener stop is possible, but if you use Sodium Alum or Potassium Alum, you will cause Aluminum Hydroxide to precipitate unless the Stop is properly designed. Going into such a Stop from the developer carries in a lot of base and this can have a bad effect on film leaving a white scum. Also, loss of Aluminum will decrease hardening strength.

Chrome Alum can be used, but you need a rinse before it and one after it to prevent carryover of solutions.

So, it can be done, but the best way is to PRE-Harden before development, then rinse and then begin the normal process. This gives the best of all possible words regarding work flow.

Of course, the best way to do it is to use a film that is not chewed up by the bleach, or use a bleach that does not chew up the film. That can be done as well, but that was not the premise of the original post, and I am trying to just answer that.

PE

 

[mrred]

Thanks for the info PE. I'm not that head strong for a stop-hardener. I just want to solve a problem.

The chemistry I am using is a combination of what I can get and what works; ie: I use dichromate because they will actually ship it to me. It has given me the results I was looking for with regards to tone, grain and scanibility.

I have crap loads of film in the cooler that I would like to use up and looks very nice, other that some emulsion falling off. That is why I as what I have been asking. It would not be the end of the world if I could not make that work, but I tend not to give up on something...

 

[holmburgers]

mrred, could you tell us your procedure for your process, or perhaps what film you're using? Is the emulsion literally falling off? I'm wondering if there's not something else that could be done to fix the problem, but at any rate I've enjoyed the discussion and as usual, PE's insightful comments.

 

[mrred]

This is what I have done so far.....

I mix some "magic water" with 8g of hypo in 250 ml dist water. This makes it easier to adjust the right amount for each film type.

Now, for this example I will use Foma 100R. I use Foma 100R because 1) I had some left, 2) I know it works fine with the foma kit (I have one) 3) The foma kit makes other films suffer from emulsion peeling but 100r does not.

I use a motor base (beseler) with a makeshift drum that takes 200 ml of developer fluid. I mix Dektol 1:2 and 12ml of "magic water" @ 12 mins to get the exposure for 100r to match the foma kit.

I rinse with dist water 5-10-20 as per ilford.

I use a reduced bleach formula because of this issue. 6g of Dichromate in 1l dist water. I get lab grade Sulfuric acid (%20) and dilute it 1:9. I mix the two 1:1 (200 ml) as one shot @ 5 mins

When I dump the bleach out, this is where the "bits" of emulsion flow down the drain.

rinse 5-10-20

Clearing agent is 30 grams of sodium metabisulfite with 1 liter of dist water. I use 200 ml @ 5 mins as 1 shot

rinse 5-10-20

light flash, about 1 min in my environment. Too little the blacks don't develop and too much your images will "glow" with halo's.

Develop in dektol 1:2 for 5 mins.

rinse 5-10-20

fix (I use kodak rapid with hardn)

rinse 5-10-20

photo-flo, hang to dry.

Here is an example of a good frame, sorry I threw out the bad frames already.

When it works, it seams to work well. Taming this beast seems (or needs to) to be a long-term goal.

 

[Photo Engineer]

Interestingly enough, over flashing should do nothing to the image quality. If it does, it indicates a process problem, usually underdevelopment in the first developer. So, that is one immediate thing that I see in your note.

As for bits of emulsion floating out, this indicates that the emulsion is not sticking to the base. If it were being totally destroyed by the bleach, usually it would dissolve rather than appear as bits. It can happen, but bits are rare in this case. Therefore, I think that there is a hint that the subbing is the problem.

In any case I suggest preharden, wash, first developer (with more time?), stop or rinse, flash, bleach, rinse, clear, etc......

PE

 

[holmburgers]

Have you checked the temperature of the bleach? Sulfuric acid can raise the temperature quite a bit, it might be worth checking that.

Also, isn't a sodium sulfite clear usually the recommended agent when using K-dichromate? As I understand it, metabisulfite and bisulfite are used only with a permanganate bleach; though this wouldn't explain the emulsion problem.