Lith emulsion from Haist (Steigman)

[thio]

Thanks!

 

[dwross]

PE
Do you have the reference/citation form Haist to Steigmann original paper?

A. Steigmann, "Cadmium Chlorobromide and Chlorobromide Emulsions with Negative Speed," Scientific Photography, H. Sauvenier, Editor, Macmillian, New York, 1962, pp 122-127

Referenced on p. 494 of Modern Photographic Processing, Volume 1, by Grant Haist, 1979

 

[Photo Engineer]

Thanks Denise. I had stowed away my copies of Haist and that was the only source I had.

PE

 

[dwross]

And I wouldn't have known where to look without your reference to it. What a team!

 

[RauschenOderKorn]

Add 12 ml of Magnesium Oxide solution (no concentration given)

In my copy it reads: "Add 0.3g of magnesium oxide."

 

[Photo Engineer]

As I note, the actual amount depends on the acid/base content of gelatin. It may be an obsolete ingredient now depending on whether the Mg ion had some other effect.

PE

 

[RauschenOderKorn]

Typical Lith Emulsions show high contrast and high Dmax, like e.g. the old Orwo lith films which are based on the old Agfa formulas (e.g. FO5 and FO6, lith film, ortho, dmax 5 or 6)

I understand that cadmium and rhodium are contrast enhancing, and the emulsion is supposed to be digested to max speed and gradation. So this emulsion can be expected to show hard gradation.

But what Dmax can be expected from an emulsion like this? How can the Dmax be influenced?

 

[Photo Engineer]

On film, I would expect a Dmax of about 4.0 at normal coating levels, but this can vary with silver content per square meter.

PE

 

[thio]

In my copy it reads: "Add 0.3g of magnesium oxide."

Could you scan this a few pages of formula from your Haist?

 

[thio]

I understand that cadmium and rhodium are contrast enhancing, and the emulsion is supposed to be digested to max speed and gradation. So this emulsion can be expected to show hard gradation.

Cadmium and albumines play the role of inhibitors for crystallisation/physical ripening of AgCl and AgClBr emulsions (according to Steigmann recearch)

 

[Photo Engineer]

Well, the theory for Cadmium can be blown out of the water immediately. Cadmium can be added during the making, ripening or just before coating. The latter addition has no effect at all on ripening but can have the same effect. It can also be added in ranges from mg/mole of Silver to grams/mole. It can also tone the image.

PE