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Emulsions 2A and 2B Developing-Out Contact Printing Paper

 

The recipes follow the same basic formula as 1A/1B except for the starred (*) changes:    

Salts:
4 g Masu seawater salt dissolved in
20 ml distilled water.
0.5 g KCl (Potassium chloride).
2 g citric acid.
0.7 g Ammonium bromide dissolved in
*5 ml distilled water.
*12 drops 1% KI solution.

Silver:
5.6 g AgNO3 dissolved in
25 ml distilled water.

Finals:
12 drops Photoflo 600.
12 drops 1% KI ('2B' only).
* 10 ml distilled water ('2B' only).
* 5 ml Everclear ('2B' only). 
15 drops glyoxal.


Observations, conclusions, and further questions

1)  The emulsion bubbling in batch 2A didn't improve with the elimination of Everclear.  The only thing left to consider was the glyoxal.  Apparently, it can get too old.  I replaced the glyoxal in the small dropper bottle I use with fresh from the main bottle for batch 2B.  The dropper bottle had originally been filled from the same main bottle, but the big bottle is stored in a dark, cool cabinet and seems to keep better there, because 2B was much better, although not perfect.  I still ended up using a second hardening fix.  I won't know for sure if the problem is glyoxal until I can get brand new fresh stuff.  I'll order as small an amount as possible.  Big bottles are false economy of scale if glyoxal goes bad with age. 

This finding puts into question an observation I made a couple of months ago when I started experimenting with different gelatins.  I used 300 bloom pig skin gelatin in a recipe.  It gave brilliant, crisp blacks but the surface of the prints developed tiny bubbles in an acid stop bath.  Changing to a plain water stop bath eliminated the problem, so I decided there was a pH issue that needed chasing down.  Now, I don't know if aging glyoxal was coming into the picture.  I'll try the pig skin gelatin again when I get fresh glyoxal.

2)  I added 1% KI to the first precipitation, and left it out of the finals for 2A.  I then added it as part of the finals in 2B — to absolutely no discernable difference.  KI use needs a very intensive and extensive examination.

3)  On 1A and 1B, besides a mild case of the peppers (mild enough for me to consider them 'fairydust' — more about that here), I thought I noticed a few black spots.  I had to look under a microscope to see them, and there weren't very many, but unwelcome none the less.   The only thought I had on the cause was the Masu sea salt.  I've had the package I drew from open for a while.  Natural sea salt doesn't have additives to prevent clumping.  It was harder to dissolve the Masu than it had been when I first opened the plastic package.   I guessed that the silver was forming big black 'conglomerates' around any sea salt clumps.  For emulsion batch 2A/2B, I deliberately didn't try to completely dissolve all the Masu.  The spotting and peppering was much worse.  From the scan, it's hard to see the peppering, but it's there.  Easier to see is the black spot at the base of the girl's neck.

When I use lab grade sodium chloride in recipes, I often leave a third of the total amount called for dry.  I sprinkle that over the top of the emulsion right after subsurface silver addition.  The technique seems to work like a "poor man's" double-run addition.  It works because high quality sodium chloride dissolves quickly and completely, unlike the natural, unrefined evaporated sea water.


 

Step tablets from 2A and 2B, scanned together a the same time.  Each batch runs from #'s 4 to 16.

There are far fewer black spots on 2B.  I don't know for sure why.  Possibilities to be chased down include:

1) Aging the emulsion: for one reason and then another, two weeks passed by between coating with 2A and with 2B. 

2) KI added as a final.

3)  Older developer (more about that follows).

4)  Pure coincidence (unlikely, but possible nevertheless).

5)  A combination of two or more of the above (very likely, and a real puzzle to tease apart).

 


 

Step table print on '2A', with three enlarged crops.

The black spots are plainly visible.  The peppering is almost invisible to the naked eye, but the size and extent of the grains is still a detriment (as opposed to a light fairydusting).  On the extreme closeup of the concentric squares, you can see how the odd pepper grain cuts across the lines, reducing the sense of resolution, even in the actual size print. 


Here's a real mystery story.  I've thought I've noticed a reduction in peppering if a print is developed in old developer (my standard, 'Def55Dwr' here).  It has seemed that prints developed at the end of a session are cleaner than those processed in the beginning, but my emulsions of late have all been too clean to really test this out.  2A/2B was smutty enough run a test.   'Cosmos and Bee' was printed first, and 'Bics on the Beach' was printed last, with a couple of hours in between when the developer sat out in a lightly covered tray.  The difference is striking.  The peppering in the Cosmos print is very evident but almost non-existent in the Bics print.  I need to mix up a half dozen — at least — different developers and run a single emulsion batch of prints through them all.  I have tried a number of developers, but not all on the same emulsion at the same time, and without watching closely for effects on peppering.   Note: On the full size prints (below enlarged crops) I left some of the base paper showing to better illustrate the color of the emulsion.  (Fabriano Artistico Extra White HP)

'Bics on the Beach', a 5-color silvergum print, 3.5" x 5.5", and close-up crop of same.


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