Edgar Hyman Formula--Sodium Chloride Omission--Acutance

[lensmagic]

Here is Edgar Hyman’s Microdol Substitute Formula:

Metol....................................5 grams
Sodium Sulphite, anhydrous........100 grams
Sodium Chloride (iodine-free)... 30 grams
Water to make.......................1 litre of stock solution.

The sodium chloride is said by Bill Troop (FDC, p. 69) to have the ability to decrease graininess. I assume the salt provides solvent action on the emulsion. In seeking better sharpness, one dilutes the stock solution 1:3 or 1:4. FDC, p. 55. Might the omission of the salt further increase sharpness by reducing the solvent effect of the developer solution?? Now we are close to D-23 (5 grams metol versus 7.5 grams metol). Would omission of the salt affect the pH of the developer solution??

 

[CBG]

This post might want to be moved into the articles section under film developers.

 

[Ian Grant]

If you want higher acutance you need to also reduce the Sulphite and increase the pH and use at around 1+9.

Ian

 

[craigclu]

This post got me remembering back to using Microdol-X many years back. I pulled out an old (at least 15 years) 1L envelope and noticed that the contents are stated as 120g total. I had always thought of the SS at 100g/L in Microdol-X and the low total weight in the packet now has me wondering at the difference? Any ideas?

 

[Anscojohn]

This post got me remembering back to using Microdol-X many years back. I pulled out an old (at least 15 years) 1L envelope and noticed that the contents are stated as 120g total. I had always thought of the SS at 100g/L in Microdol-X and the low total weight in the packet now has me wondering at the difference? Any ideas?

******
I have a formulary someplace for pseudo-Microdol X that calls for 125 gms sodium sulfite per liter.

 

[Christiaan Phleger]

I don't think its possible to improve upon Kodak Microdol-X for this type of developer. The recently discussed mercaptan included in the Kodak product does a double duty as a sequestering agent and for dichroic fog, and probably adds some value of sharpness, especially at higher dilutions I would think.

 

[Ian Grant]

There's no Dichroic fogging without the Mercaptan with most modern films, I tested the formula back in the spring with Ilford & Foma films. But in prcatice with modern emulsions there's less of a difference between a dev like this and ID-11/D76 or even Rodinal as the films themselves have a more inherent fine grain and are less affected by choice of developer with regards to final grain size.

Ian

 

[lensmagic]

How about the central question: will omitting the salt serve to increase acutance?

 

[Ian Grant]

Maybe slightly but not significantly without cutting the Sulphite as well. You might as well just use D23.

Ian

 

[Denis K]

lensmagic, Have a look at the following thread (on a different board). It is one of the best I've seen on the internal working of Microdol-X. Richard Knoppow discusses the Sodium Chloride issue. His explanation sounds credible to me.

http://www.photokb.com/Uwe/Forum.aspx/photo-darkroom/1480/To-Richard-K-Perceptol-x-Microdol

I too have wondered about the fact that the Microdol-X and D-76 contain about the same amount of sodium sulfite and yet people always claim that the sulfite is what "disolves away the grain". Maybe that is related, but I think it's more complicated than that and includes the pH of the solution, the low activity of the developer and the longer time in the developer than when using D-76. I've used Microdol-X in the past and seem to be one of the few who used it full strength as opposed to 1+3, but them I was after something other than acutance.

Denis K

 

[Ian Grant]

Only problem is he says Perceptol contains Bromide, which it doesn't.

Ian

 

[Denis K]

Only problem is he says Perceptol contains Bromide, which it doesn't.

Ian

Ian, Look further down the thread. Richard said that in his 22 Mar 2005 post at the bottom of the thread. He claims he thinks it was an error in the MSDS. Someone should compare Microdol-X to D23+Bromide and see how they compare.

Denis K

 

[Ian Grant]

It was an error in an MSDS.

Adding Bromide doesn't work anything like as well as adding Chloride to achieve finer grain. Bromide is added to some Replenishable developers as a starter but in quite low levels, it has a detrimental effect on contrast & Dmax if it's too high.

Ian

 

[craigclu]

This post got me remembering back to using Microdol-X many years back. I pulled out an old (at least 15 years) 1L envelope and noticed that the contents are stated as 120g total. I had always thought of the SS at 100g/L in Microdol-X and the low total weight in the packet now has me wondering at the difference? Any ideas?

I just now noticed that the package was a 1 quart pack (946ml) so the numbers are closer than I first thought.....Sorry for bungle!