Formulating a sharp solvent MQ developer

[Harold33]

To achieve a true increase of definition and/or sharpness (acutance) in a classic MQ developer, the most commonly used chemical strategies are :

1. the diminution of solvent effect by diminution of the sodium sulfite content to 75-80 gr. by liter ;
2. the use of potassium bromide to prevent discontinuities caused by borax ;
3. the replacement of hydroquinone by ascrobic acid (or sodium isoascobate) ;
4. the replacement of hydroquinone by phenidone.

Developers such as Adox MQ, Agfa 44 (Ansco 17), DuPont ND-2, are typical examples of 1-2, Kodak D-96A is an early example of 1-3, while 4 is illustrated by the family of FX developers.

But according to Crawley, there is also a lesser-known way to go in the same direction. According to him : « The buffering of borax with boric acid does not seem to improve definition, altough (…) sharpness is improved » (as quoted in Anchell & Troop’s Film Dev. Cookbook, p. 44).

As far as I know, Crawley is the only researcher who claimed that boric acid had such a property. In most textbooks, boric acid is quoted as a buffer component used to stabilize borax or to lower pH, but nothing else.
Does anyone have an opinion to share on this point ?

If Crawley’s claim is true (?), I wonder what amount of boric acid is needed (at least 2 gr. ? more ?) and what amount of supplementary borax is needed to counterbalance the pH lowering ? (for example, ID-68 use boric acid : 2 gr. + borax : 7 gr., when Adox-like developers use 4 gr. of borax only).

[Keith Tapscott.]

To achieve a true increase of definition and/or sharpness (acutance) in a classic MQ developer, the most commonly used chemical strategies are :

1. the diminution of solvent effect by diminution of the sodium sulfite content to 75-80 gr. by liter ;
2. the use of potassium bromide to prevent discontinuities caused by borax ;
3. the replacement of hydroquinone by ascrobic acid (or sodium isoascobate) ;
4. the replacement of hydroquinone by phenidone.

Developers such as Adox MQ, Agfa 44 (Ansco 17), DuPont ND-2, are typical examples of 1-2, Kodak D-96A is an early example of 1-3, while 4 is illustrated by the family of FX developers.

But according to Crawley, there is also a lesser-known way to go in the same direction. According to him : « The buffering of borax with boric acid does not seem to improve definition, altough (…) sharpness is improved » (as quoted in Anchell & Troop’s Film Dev. Cookbook, p. 44).

As far as I know, Crawley is the only researcher who claimed that boric acid had such a property. In most textbooks, boric acid is quoted as a buffer component used to stabilize borax or to lower pH, but nothing else.
Does anyone have an opinion to share on this point ?

If Crawley’s claim is true (?), I wonder what amount of boric acid is needed (at least 2 gr. ? more ?) and what amount of supplementary borax is needed to counterbalance the pH lowering ? (for example, ID-68 use boric acid : 2 gr. + borax : 7 gr., when Adox-like developers use 4 gr. of borax only).

The standard D-76/ID-11 formula works perfectly well and doesn't need any tinkering with. Ilford still recommend ID-11 diluted 1+3 when maximum sharpness is required in their technical publications.

Borax actually releases boric acid when it is dissolved according to this link and borax is already an effective buffer on it's own. You could try D-76d, but I much prefer the standard formula.

http://www.borax.com/detergents/pheffect.html

[steven_e007]

I have no expertise at all in developer formulation, although it interests me. So, just curious:


"4. the replacement of hydroquinone by phenidone".

Isn't phenidone a substitute for metol? I have read that phenidone doesn't form mackie lines so easily as metol and since edge effects give the impression of higher acutance, would an MQ developer be a better option for high acutance than PQ?

"2. the use of potassium bromide to prevent discontinuities caused by borax ;"

Please can you explain this? What are the 'discontinuities caused by borax" ?

[Keith Tapscott.]

Ryuji Suzuki wrote something that might interest you here about D-76, http://jeffreysoper.com/node/101 but I still don't see any point in making anything other than the standard formula.

[Keith Tapscott.]

I have no expertise at all in developer formulation, although it interests me. So, just curious:


"4. the replacement of hydroquinone by phenidone".

Isn't phenidone a substitute for metol? I have read that phenidone doesn't form mackie lines so easily as metol and since edge effects give the impression of higher acutance, would an MQ developer be a better option for high acutance than PQ?

"2. the use of potassium bromide to prevent discontinuities caused by borax ;"

Please can you explain this? What are the 'discontinuities caused by borax" ?

It seems that Phenidone and it's derivatives can produce a slight speed increase over metol, but also slightly coarser grain. Play around with the basic D-76/ID-11 formula with metol and another replacing metol with either 0.2 gram of phenidone or dimezone-s and see which you prefer.

[Keith Tapscott.]

Here is a Microphen type developer.

http://www.film-and-darkroom-user.or...82&postcount=1

[Harold33]

"4. the replacement of hydroquinone by phenidone".

Isn't phenidone a substitute for metol? I have read that phenidone doesn't form mackie lines so easily as metol and since edge effects give the impression of higher acutance, would an MQ developer be a better option for high acutance than PQ?

You are right ! It's a misprint : Read metol for hydroquinone.

"2. the use of potassium bromide to prevent discontinuities caused by borax ;"

Please can you explain this? What are the 'discontinuities caused by borax" ?

In his famous article, Crawley explain that "in a sensitive carbonate developer the introduction of 0.1 grams per liter of borax will produce a slight sheen". With recent film, I never saw this 'sheen', but it was occasionaly visible with films like 'old' Tri-X [before 1980] souped in D-76.

[Alienguru]

You could search for Mytol. Thought it doesn't contain any Potassium bromide, it is said to produce low base fog.

[Harold33]

The standard D-76/ID-11 formula works perfectly well and doesn't need any tinkering with. Ilford still recommend ID-11 diluted 1+3 when maximum sharpness is required in their technical publications.

Of course, but my question is about chemical composition.

[Alan Johnson]

From Crawley, BJP Dec 16 1960:
"...as regards absolute granularity per film speed...D-76 remains unsurpassed; to some extent it wins by a foul,since the definite sheen imparted to a film by its use acts as a sort of dichroic diffusing screen during printing...D-76 gains in absolute grain refinement by losing in acutance..."
"The buffering of borax with added boric acid does not seem to improve definition,although the borax sheen is removed and sharpness improved"

It seems Crawley considered the sheen left by D-76 reduced sharpness but was removed by boric acid.

The 60's films often contained less iodide than modern films and were more prone to forming edge effects so perhaps this may not generally be true today.