Modern Rodinal Substitutes Part II

[Ian Grant]

Apologies for having to start a new thread but I can't read or even access the first to reply to posts.

So with a bit of telepathy

Well, there's a problem there, as it's really hard to measure pH accurately when it gets much above 12.5 or so. You have to start getting special electrodes and the like.

But for MSDS work, it doesn't have to be too precise.
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Kirk

A point that's being missed is that A&O give a figure of 2.7% Potassium Hydroxide not 3% in older Agfa MSDS.

The pH is around 14 sure, but the actual requirement is the pH of the working dilute solution rather than the concentrate which is given elsewhere as pH 11.55, which I commented on in the first post of the thread.

Way back Ron (PE) mentioned adjustments to Rodinal before bottling, the question we need to ask is are they adjusting on the basis of the concentrate, or also doing some tests on a dilute sample, as this will be a far more accurate indicator.

Can someone please post a link to this continuation on the original post.

Ian

[Ian Grant]

I don't understand why you are not more sensitive regarding your release of misinformation /misdirection but well, OK. whatever. You did finally get it right on your third try!

I thought that text looked famaliar... I still have notes notes from Dr. Iwano's lectures - He is a very cheerful person. The last time I spoke to him was when the director of IPI was here, some months ago. (Photographer Eiko Hosoe was there as well - if you are one of those who like his work/ideas)

Anyway I was quite happy to be reminded of Dr. Iwano.
I think I gave him a really hard time!

Aplogies I actually thought I'd given the right Fuji Patent No, when you speed read 20/30 in a row saving the relevant for later reading it's easy to grab the wrong number

Yes I know Eikoh Hosoe's work some is very interesting but I've not seen a book or exhibition yet.

Ian

[Alan Johnson]

You will be happy to find out that the experiment failed when I tried to bring the concentrations of p-aminophenol and ascorbic acid up to the level we're looking for in a concentrated stock. The only real difference is the substitution of about 29 grams of potassium ascorbate for 192 grams of potassium sulphite in 500 ml. What am I missing?

Ascorbate may not regenerate p-aminophenol.
I made some PaRodinal,added sulfite to make it solvent,then reduced the pH to about 8.5 by adding either ascorbic acid or boric acid.The ascorbic acid did not seem to give any extra activity compared to boric acid.I found no benefit in modifying PaRodinal in this way,it merely produces a developer that takes twice as long as D-76 to produce a rather similar result.IDK if the p-aminophenol version is more resistant to oxidation than D-76.
However,this was only one experiment but IIRC many have found adding sodium ascorbate to Rodinal to have some benefit,I don't know the cause of that.

[Ian Grant]

I tried a search of USP 3765892 and find no reference to benzene sulfonates. The "find" utility in the PDF file does not find it, but it is found in the search of the text version. It becomes clear though that there are errors such as the claim of an antioxidant called potassium fulfite!

Errors do happen. The point is that we do not know for sure in spite of that patent.

I might add, in support of my comments, that diethy hydroxyl amine, which is claimed as an antioxidant, would be a very poor one for B&W developing agents, especially at that pH.

PE

The Text part is OCRed which is why Text usually not there for old poor quality photocopied Patents.

Patents are waffle full of irrelevances hiding facts, ascorbic acid won't work at that high pH (examples) as an antioxidant either.

Kodak's ppd/Benzenesulphonate Patent is more interesting as the citation is to a an anti-oxidant Patent.

Ian

[Photo Engineer]

PDF files usually search well using the PDF find utility. I use it all the time. But the active word is "usually". I was just warning the readers.

I'm still not sure what role these two compounds play, nor am I sure that they are identified correctly.

PE

[Kirk Keyes]

Sodium Benzene sulphonate

Well, in the pesticide world, it's used as a soap (detergent).
http://www.pesticideinfo.org/Detail_...Rec_Id=PC34890

[Ian Grant]

Well, in the pesticide world, it's used as a soap (detergent).
http://www.pesticideinfo.org/Detail_...Rec_Id=PC34890

But is it ?

I think it's right on the borderline for classification, wetting agents are longer chains. A 2nd Kodak patent has quite similar although more complex organic compounds sulphonates/sulphonic acid salts as antioxidants but they aren't long chain.

In the Kodak PPD/Benzenesulfonate Patent they say it's used to help PPD dissolve, that's nonsense it's there for another reason.

There's some misinformtation in these early Patents, later Fuji hide it, although newer Patents are more open.

You can use a detergent as an Insecticide, or a soap, spray a solution of it on the insects and they drown, but if it's an antioxidant it'll be better

Ian

[Photo Engineer]

Ian;

It is well known that Benzene sulfonates help PPDs dissolve! In fact, a close analog, pTosyl (para Toluene Sulfonic Acid) is used for all CD3 developers and CD6 developers today.

PE

[Ray Rogers]

Ron

Both you and Ian have mentioned pH as one factor relating to usefulness of compounds clamed as antioxidant... Can you explain?

What other factors might be involved?

What could make one chemical a good AO in one case, but not in another?

Correct me if I am wrong, but isn't being an AO or not depandant upon the specific rxn being examined?

[Kirk Keyes]

But is it ?

I think it's right on the borderline for classification, wetting agents are longer chains.

Well, that's plain wrong. Follow the link I gave it is it clearly listed as a soap (i.e. a detergent).

In the Kodak PPD/Benzenesulfonate Patent they say it's used to help PPD dissolve, that's nonsense it's there for another reason.

Have you heard of co-solvents? A small amount of one compound is added to help another compound dissolve into the primary solvent (water in this case). The reason benzene sulfonate is going to be a good cosolvent is that it has both hydrophobic (water hating - the benzene part) and hydrophyllic (water loving - the sulfate part) functional groups in the molecule. That's pretty much how detergents work too.

You can use a detergent as an Insecticide, or a soap, spray a solution of it on the insects and they drown, but if it's an antioxidant it'll be better

Not sure why any possible antioxidant properties make a difference for pesticides...

But for use as a soap in pesticides, it is not going to be the major toxic component in those pesticide formulations!

[Kirk Keyes]

It is well known that Benzene sulfonates help PPDs dissolve! In fact, a close analog, pTosyl (para Toluene Sulfonic Acid) is used for all CD3 developers and CD6 developers today.

Didn't benzyl alcohol serve this porpose as well - as a cosolvent?