Chemical compounds and their effect

[pkr1979]

Hi all,

While comparing different developers Im trying to understand how the different chemicals in the developer affects the end result. Note that this is for reversal developing Tmax400, however Im assuming som universality.

These days Im comparing Ilford PQ Universal with a Orwo recipe where Im using Metol instead of Phenidone. The one liter working solution of PQ is as follows (for the second development this was diluted to a little stronger then half strength):

Phenidone 0,2
Sodium Sulphite (anh) 21
Hydroquinone 5
Potassium Carbonate 16
Sodium Hydroxide 0,9
Potassium Promide 0,8
Benzo xg

And the one liter working solution of the Orwo recipe is as follows (same for both 1st and 2nd development):

Metol - 2g
Sodium sulphite (anh) - 25g
Hydroquinone - 10g
Sodium carbonate (anh) - 20g
Potassium bromide - 6g
Sodium hydroxide - 5g

Results:
PQ gives more 'glow' and volume or depth, they are also warmer.
Orwo gives sharper positives with more clarity.

Id be interested to know which chemicals are causing these different charecteristics.

As far as I understand Potassium Carbonate gives warmer results then Sodium Carbonate, so I assume using that in the Orwo recipe could produce warmer positives. But is it then possible to predict negative side effects, ie a loss of sharpness?

Ilford also seem to advise to increase the content of potassium bromide to get warmer results (http://lostlabours.co.uk/photography/formulae/developers/dev_cool_wam_tones.htm). However, there is a lot more potassium bromide in the Orwo recipe then the PQ recipe.... Im assuming the Sodium Hydroxide is neutralizing it?

I know that toning is also an option but Id like to know how the different chemicals can be adjustet to get a spesific end result. Is it possible to identify why these two developers gives the resullts they give based on their content? Clearly Id like what both developers provide combined.

Cheers
Peter

 

[mohmad khatab]

Hello my dear colleague.
I love Oslo..
In fact, you are absolutely right, I have always liked a great ORWO recipe.
I just replace Dichromate Bleach, and I use Permanganate.
Other than that, the ORWO Formula is really more than amazing.
My greetings

 

[Ian Grant]

A PQ developer is warmer working than the equivalent MQ, there were complaints that Ilford ID-20 PQ was giving shifts in image colour with use, so it was re-formulated adding Benzotriazole as ID-62 and then released in liquid form as PQ Universal. Ilford also released a variant of ID-62 as a powder developer ID-78.

So the simple answer is the Agfa/Orwo formula needs more Bromide as it's a MQ developer, however with modern warm-tone papers developers with this level of bromide are fairly ineffective, they worked well with older warm-tone papers with Cadmium salts in the emulsion.

Ian

 

[pkr1979]

Thanks @Ian Grant

Does that mean that in principle, adding more Bromide to the Agfa/Orwo formula one should expect warmer results? But depending on content of paper/film the effect might not be that pronounced?

Do you have any idea, or guess, on how much bromide should be added?

Cheers
Peter

 

[Ian Grant]

Adding more Bromide to an MQ developer will decrease the activity of the Metol once you reach a certain point. In fact Agfa/Orwo left out the Metol in two of their warm tone developers. Adding extra bromide works better with PQ formulae. This only works with Chloro-Bromide warm tone papers.

Adding extra Bromide is definitely not a good idea for reversal processing, you'll compromise Dmax.

Ian

 

[pkr1979]

Adding more Bromide to an MQ developer will decrease the activity of the Metol once you reach a certain point. In fact Agfa/Orwo left out the Metol in two of their warm tone developers. Adding extra bromide works better with PQ formulae. This only works with Chloro-Bromide warm tone papers.

Adding extra Bromide is definitely not a good idea for reversal processing, you'll compromise Dmax.

Ian

Thanks @Ian Grant

 

[pkr1979]

@Ian Grant , one more thing... is there any reason not to replace the sodium carbonate in the Orwo-formula with potassium carbonate?

 

[Ian Grant]

@Ian Grant , one more thing... is there any reason not to replace the sodium carbonate in the Orwo-formula with potassium carbonate?

The substitution is 1.3g Potassium Carbonate (anhyd) for 1g Sodium Carbonate (anhyd), but that Owo formula is not a good idea for films.

Ian

 

[pkr1979]

The substitution is 1.3g Potassium Carbonate (anhyd) for 1g Sodium Carbonate (anhyd), but that Owo formula is not a good idea for films.

Ian

I figured Id use it for reversal. Did you test it?

 

[Ian Grant]

Which Orwo formula is it, formula number ? I really don’t think it's a good idea to use an MQ developer with that level of Bromide for reversal processing.

Ian

 

[pkr1979]

@Ian Grant , its this: http://lostlabours.co.uk/photography/formulae/developers/rev_filmotec.htm

I replaced the phenidone with metol. I didnt have any phenidone and wasnt aware of the different characteristics and consequenses... I did order phenidone now though and will use that instead of metol.

 

[Ian Grant]

OK, now I know it's the Filmotec Orwo 842 2nd developer, it makes sense. The restraining effects of the 6g of Bromide will help give cleaner highlights, it's also going to be higher contrast than PQ Universal.

I must put the reversal developer in my Database.

Ian

 

[Raghu Kuvempunagar]

OK, now I know it's the Filmotec Orwo 842 2nd developer, it makes sense. The restraining effects of the 6g of Bromide will help give cleaner highlights, it's also going to be higher contrast than PQ Universal.

OP is using the same developer, i.e. his MQ adaptation of Orwo 842, as his first developer too. Seems like a lot of Bromide for a first developer.

 

[Ian Grant]

That's OK, the Filmotec Orwo 829 1st developer is the same except for the addition of 5g Potassium Thiocyanate.

It's a higher pH compared to PQ Universal which will counter some f the restraining effects of the increased Bromide. Both an earlier 1940 Agfa and the Gevaert reversal 1st developer have high Bromide levels.

Ian

 

[pkr1979]

@Ian Grant , would you have any concerns replacing the sodium carbonate with potassium carbonate? Im hoping for slightly warmer results and finer grain?

 

[Ian Grant]

Film emulsions are Bromo-iodide so you are unlikely to see an increase in warmth. With Bromo-chloride papers Potassium salts increase the warmth but the increase is only very slight, that goes for finer grain as well.

Ian

 

[pkr1979]

Film emulsions are Bromo-iodide so you are unlikely to see an increase in warmth. With Bromo-chloride papers Potassium salts increase the warmth but the increase is only very slight, that goes for finer grain as well.

Ian

OK - thanks

 

[pkr1979]

@Ian Grant , do you know if the Filmotec Orwo 842 recipe is based on a paper developer and therefore suitable as one? I also mixed the chemicals with water at 50C instead of 35C and unsure if that will be of any consequence?

 

[Ian Grant]

I don't think i's based on a paper developer, but it may be Universal and work with paper. you'll need to try it,

Ian

 

[pkr1979]

I don't think i's based on a paper developer, but it may be Universal and work with paper. you'll need to try it,

Ian

OK, thanks - its clearly warmer with phenidone, but PQ is still better for TMax 400