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Jobo Alpha

Don_ih

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I was looking through the MSDS for Jobo Alpha and I thought some people might find it interesting.

Black & White Developer part A

Water 80-95%
Sodium carbonate 10-15%
Ethylenediaminetetraacetic acid disodium salt 0.5-2%

JOBO alpha developer Part B

Water 85-95%
Potassium 2,5-dihydroxybenzenesulfonate 1-5%
N-Ethyl-N(2-hydroxyethyl)-p-phenylenediamine sulfate 0.5-2%
Sodium sulfite 3-10%
1,2-propanediol < 0.5%
 
I though CD4 was a C41 developer, not B&W?
 
Craig said:
I though CD4 was a C41 developer, not B&W?
Click to expand...

The way color developers work means they also develop B&W. In fact, that's a crucial requirement.

Color development works as follows (simplified)
* The color developer develops an exposed silver halide image into a metallic silver image.
* During this development, the developer is oxidized and these oxidization products emerge at the exact spot where silver development took place.
* The oxidization products of the developer combine with the color couplers in the emulsion, forming dyes. Because these oxidization products are localized where the silver image was developed, the color dye image also emerges in the same place.

In further processing steps, the silver image is (usually) bleached and fixed away.

Given the mechanism outlined above, it's also possible to use a 'color' developer to just develop a B&W silver image and leave it at that.
 
Is Potassium 2,5-dihydroxybenzenesulfonate regular photographic hydroquinone?
 
Don_ih said:
Is Potassium 2,5-dihydroxybenzenesulfonate regular photographic hydroquinone?
Click to expand...

No, it's hydroquinone monosulfonate potassium, also used in E6 FD. Much milder than hydroquinone.
 
Craig said:
I though CD4 was a C41 developer, not B&W?
Click to expand...

Most color developers will appear very weak with typical B&W materials, since the oxidized color developer sticks to the silver halide grain and prevents fresh developer from appearing at the development center. In color film the used developer us reacted with the color couplers, therefore development would go to completion. In B&W film you have to add a suitable compound to your developer, and Jobo apparently chose a weak secondary development agent: HQMS.

This approach is not exactly new, there was Atomal 49, there's Jay De Fehr's Halcyon, there's MCM 100 and Crawley's FX-10, and probably more.
 
I'm like this Jobo Alpha developer. It is better than my go to two-bath Pyro because it gives box speed and in fact can be pushed. I will try some Delta 3200 later.

Here are a couple HP5 4x5 shots developed in Jobo Alpha.

At Winnipeg. There's a teeny "Japanese Garden" next to the hotel


Vancouver airport. We have been to YVR many times, including a couple times as the layover spot, but never did we have an 8 hours layover - until when we went to Winnipeg. So I took out my 4x5 and made a photograph. Gibellini 4x5 Cooke 1880s RVP.

 
@Richard Man -- those shots look very nice, tonally, and there appears to be good detail throughout.
 
I would just like to briefly clarify some inaccuracies about this developer.
It does not contain CD4.
There are no models for the recipe.
The aim was to create a developer that has no specific weaknesses.
 
@Klaus Wehner what's the best starting point to find the right dev time for more unusual films, e.g. Shanghai GP3, or Kodak Double X?
Thanks
 
I was genuinely asking, because I thought it "looked" like CD4 when I saw the MSDS but CD4 is 4-(N-Ethyl-N-2-hydroxyethyl)-2-methylphenylenediamine sulfate.
 
Don_ih said:
I was genuinely asking, because I thought it "looked" like CD4 when I saw the MSDS but CD4 is 4-(N-Ethyl-N-2-hydroxyethyl)-2-methylphenylenediamine sulfate.
Click to expand...

It's much easier to use the CAS number provided in the MSDS. Using the name in a Google search may return similar, but not exactly matching results.
 
Anon Ymous said:
It's much easier to use the CAS number provided in the MSDS. Using the name in a Google search may return similar, but not exactly matching results.
Click to expand...

Then I guess the question can be, what does this stuff do that CD4 doesn't?
 
I don't know what the components in this product are but I'm sure it will become very popular in the fullness of time for Jobo processor users.

I deeply regret selling my CPA2 some years ago.

Klaus, did you also design the Adox Atomal 49 developer?
 
Don_ih said:
Then I guess the question can be, what does this stuff do that CD4 doesn't?
Click to expand...

The difference between CD-4 and that compound in this Jobo Alpha developer is that one extra methyl group on the benzene ring. This extra methyl group is most relevant for color processing: after coupling it geometrically forces the benzene ring to twist, which makes it more difficult for aerial oxygen to attack it. This methyl group is therefore essential for archival stability of film dyes. You will see this same methyl group in CD-2 (but not in the older CD-1) CD-3 and CD-6.

This extra methyl group obviously has no such effect in standard B&W processing, so Jobo has every reason to use the simpler compound in this product. However, it may also have an effect on developer activity, so we can not simply 1:1 replace the Jobo version (CD-32, T-32) with the much easier to obtain CD-4.
 
There were some questions for me.
I will try to answer them in order over the next few days.

First of all, my thanks to Richard Mann for showing us his photos here. They do indeed have a nice modulation of tonal values and show a detail right into the deep shadows. Good work!

I am also trying exotic films and adding them to my list. (Just new is the Foma Ortho 400).
Nevertheless, I will not be able to include all films.

Although my developer has a special development kinetics due to an unusual, novel formula, it still doesn't behave in an extremely unexpected way.
This means that you can test films yourself using the same method as you would with other developers.

Typical development time for "normal films" in JOBO alpha is about 6 to 10 minutes. Films that typically need a longer development often need a development time of 15 to 20 minutes (depending on the desired contrast, of course).
The goal is to get negatives that print well with a medium gradation (2).

Specifically, I would start with a development time of maybe 7 minutes for the two films mentioned for the first test development.
It would be nice if you could briefly report on your experiences here later.
If there are any further questions, I would be happy to help.
 
Dear Keith, yes, I use it. Overall, it gives very nice results, comparing the old ORWO A 49 for the 70th, which I used those days. It is unproblematic to use and has an excellent shelf life - I had bottles which were 3 years old.
In the German forum, I collected a huge list of tested (!) developing times. You find the list at my web page:
 
N-Ethyl-N(2-hydroxyethyl)-p-phenylenediamine sulfate CAS： 4327-84-8



cd1




hair dye


 
T-32 chemical composition; ethyl hydroxyethyl-phenylenediamine sulfate also known as: ethyl hydroxyethyl sulfate aminoaniline chemical composition: ethyl hydro-ethyl-p-phenylene di￾amine sulfate chemical formula: H?C?one NHH?SO HOC? H properties, identical to the TSS. Use: Same as in the TSS. T-32 has less developing power than TSS and uses 1.5 times the amount of TSS. It advantages that it is less irritating to the skin than TSS. Therefore, it can be performed directly operated by hand during developing operation. Note; the same as for the TSS. Note: In ORWO, T-32, in Italy, T-32 is color L.X., and T-32 in May & Baker is Droxychrome.
 
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