PAGI silver chloride (gaslight) emulsion

[thio]

The workable formula from the great brochure "Testing methods for photographic gelatin (Pagi method)", 1964.
Iodide-stabilized silver chloride emulsion. With a cooking gelatin this formula gave me Grade 2-3 of contrast and about of 1/100 of bromide paper sensitivity.

3.6. Gaslight emulsion formula for photographic paper

3.6.1. Formulation

Solution A (55°C)
Distilled water……………………..400 ml
Gelatin………………………………30 g
20% citric acid..............................2 ml

Solution B (55°C)
Silver nitrate................................20 g
Distilled water............................100 ml

Solution C (about 45°C)
Sodium chloride……………………...9 g
20% citric acid.............................10 ml
Distilled water……………………..100 ml

Solution D (55°C)
Gelatin………………………………50 g
1% potassium iodide………………10 ml
Distilled water……………………..300 ml

3.6.2. Emulsification and ripening

Maintain solution A at 55°C and add solution B while stirring. After one minute at
55°C, add solution C at once while stirring and ripen for 40 minutes at 55°C. Then
add solution D and ripen for 10-20 minutes at 55°C.

3.6.3. Coating

Before coating, bring total volume of emulsion to 1.2 kg and coat in on barytaged
paper. The quantity of emulsion for coating shall be 4 ml per plate of cabinet size.

 

[Peter Schrager]

Thank you very much..!! do you have any work done with this??
peter

 

[thio]

I made a few test prints. Coating additions: glycerol, ethanol and chrom alum.
Unfortunately my coating procedure was not perfect (white dots and 'stars') and I had some problems with uneven hardening and/or adhesion to the watercolor paper support (1 mm 'knolls' appeared during final washing after fixing).

 

[dwross]

Congrats!
Nice range of densities.
Question: Why the glycerol? It's not usually a final, except rarely with film. Perhaps you meant glyoxal? It's the best hardener for paper emulsions. If you used glycerol, it may be responsible for your repellency spots, rather than the fault of your coating method.

If it's of interest, there's more about repellency spots about 2/3 down this page. http://thelightfarm.com/cgi-bin/htmleditiongen.py?chapter=Chapter4

 

[thio]

I mean exactly glycerol (=glycerine). It's a anticurling addition (humectant).
and I used chrome alum as hardener (but plan to use formalin for the some reasons).

 

[dwross]

Well, best of luck to you.

 

[thio]

Many thanks for your link! It's very interesting!

 

[Photo Engineer]

This is pretty much my Azo/Lupex formula, but I don't use Citric Acid.

PE

 

[Peter Schrager]

referencing the above formula I want to know how to bring the total volume up to 1.2kg
are we adding gelatin; water?? just a bit confused here
thanks in advance
Peter

 

[fdonadio]

referencing the above formula I want to know how to bring the total volume up to 1.2kg
are we adding gelatin; water?? just a bit confused here
thanks in advance
Peter

I was going to ask the same…

 

[RauschenOderKorn]

I was going to ask the same…

have a look at PE’s Azo/Lupex Formula (sticky thread just a few lines above this thread). PE‘s formula has aprox. 10% gelatin content in the final emulsion.

 

[Peter Schrager]

I finally made the above emulsion without the addition of extra material. Except for the fact that I somehow got the emulsion dirty it works fine without any addition of material
I coat on fixed out baryta paper and did not add any chrome alum. Had zero frilling...
Seems to be about a grade 2

 

[joho]

I have been looking to make a contact paper , is this a good starting point ???

 

[Peter Schrager]

I have been looking to make a contact paper , is this a good starting point ???

yes this is gaslight paper and can be beautiful..ignore the last part about bringing total volume up
I didn't do that and it worked fine. I have to make it again as my silver nitrate was not the best
expose with a bright 200 watt bulb about 30 inches above the baseboard...develop in developer of choice....

 

[Kino]

yes this is gaslight paper and can be beautiful..ignore the last part about bringing total volume up
I didn't do that and it worked fine. I have to make it again as my silver nitrate was not the best
expose with a bright 200 watt bulb about 30 inches above the baseboard...develop in developer of choice....

Out of curiosity, what roughly was your exposure time with the above listed conditions?

Of course it depends on the negative, but... 10 seconds, 2 minutes.... ?

 

[Peter Schrager]

roughly about the same time as you would use for AZO. somewhere in the 20-30 second range at 30 inches.