Ilford do cite ID-11 diluted 1+3 as yielding the highest sharpness while Perceptol and Microdol-X also provide good performance at the same dilution.The big problem with both the Ilford & Kodak charts is they don't take into account dilution of ID-11/D76 or Perceptol/Microdol-X where the developers begin to behave quite differently at 1+3.
Ian
What films do these data apply to, most strictly, in your knowledge/opinion?
(How were these charts actually constructed?
The developers are mentioned, but on what films?
Was there any "weighting" of the results that you know of? (80% modern 20%traditonal... or some such? )
BTW
What developers/dev. agents do you know to be better?
Yes, I've got that Patent amongst a heap of others. Example 4 & 6 are a very slight re-working of the Wellington & Ward Borax MQ developer and a side step in the evolution of D76
Ian
Would you buy it as R09 from Calbeand sell it as Gainerol
There's an interesting cemical called "Oxygen Scavenger" which is sold by a bulk photographic chemical supplier.
I've never seen it in any published formulae but it's sold in liquid form in sizes up to 1000 litre IBC's - Ammonium Bisulphite
Ian
Ray;
I can say that Dimezone-S is far better than Phenidone as an example of better all round developing agents.
PE
You would not want to put Ammonium Bisulfite into a developer!
Patrick;
My literature reports that there have been explosions associated with working with Metabisulfite due to its strong reducing power. I would prefer to work with sulfite myself.
PE
Ian;
I was comparing two developers with very similar structures under identical conditions in my thinking. Phenidone and Dimezone-S are basically cyclic hydrazine derivatives. In alkali, the Phenidone ring opens and becomes inactive much more rapidly than Dimezone-S and the activity is somewhat lower. For this reason, Kodak used Dimezone-S in the PR-10 pods due to the high alkali content and the need for quick development.
So, for a quick OTOMH answer, those are two to compare, and if you do, (and which I have done), the Dimezone-S comes out ahead.
PE
My wine-making friends sell their's. They smoke the insides of the bottles with a sulfur candle. The powers that be make them put "Contains sulfur" on the label.Patrick, there's something nagging away in my mind about Metabisulphite. Yes the early Rodinal type formulae used it & Hyroxide to form Sulphite, at one point that was the best way of producing the Sulpite in solution.
We've had this discussion before but there is also the subtle difference between Bisulpite & Metabisulpite, and last time I was in the UK I found a reference and short extract from a Kodak paper on the subject, which I posted here on APUG. Kodak Bisulpite is in fact a mixture of Bisulphite & mainly Metabisulphite, and Kodak were referring to the interchangeability of their Bisulphite with Metabisulphite. J.T Baker sell both forms in bulk.
At some point before WWII Agfa began using Sulphite, I think something else is happening as we also know that around then they were also adding anti-foggant.
The referance to Oxygen scavenger yesterdaym (Ammonium Bisulphite) was what triggered my thought, and knowing that Metabisulphite in a developer helps cut dichroic fog.
In the wine trade Metabisulpite solution is used as an anti-oxidant, and steriliser as it's more powerful than Bisulphite, but no-one seems to explain why satisfacorily, It has a lot to do with free SO2.
Ian
If we put in bisulfite or the British bisulphite along with KOH our film will see K2SO3.
Ian - do you know if what Ilford sells in dry powder (125 g bottles I think it was) back around 1980 as "Phenidone" is actually Phenidone or Phenidone-Z?
Dimezone-S at Kodak was called HMMP or Hydroxy Methyl Methyl Phenidone. It has the best balance between keeping and being a powerful developing agent.
The Bisulfite anion HSO3- decomposes rapidly to SO3-- and then scavenges oxygen to form SO4-- or sulfate anion.
The metabisulfite anion is much more powerful a reducing agent, and one reference I have seen states that it can catch fire during the grinding process to break up lumps. It undergoes exactly the same reactions as above but the initial breakdown from metabisulfite to sulfite or bisulfite (pH dependant) is very quick and strong. This is Na2S2O5 or the S2O5-- anion. The Metabisulfite gives one mole of SO2 and one mole of SO3 upon decomposition in water, both of which end up making HSO3- or the equivalent. It is acidic in water.
A second reference gives no comment about Sodium Metabisulfite catching fire. However my references do ascribe this to the Potassium salt
So, I would tend to say take precautions with the Potassium salt.
PE
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?