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"TLF #2" Full-Ammonia Bromide Emulsion, 2nd ed.

December 30, 2011

1) Preheat a waterbath for a 250 ml beaker to 41°C. 
2) Weigh out all ingredients.
Salted gelatin: In a 250ml beaker.
  Distilled water, refrig' temp 10 ml
Gelatin, photo 2.5 g
Soak the gelatin in the water for about 30 minutes.  After dissolving together in a separate small beaker, add
  Distilled water, room temp
Potassium bromide (KBr)
13 ml
7.0 g (ground fine)
Potassium iodide (KI) 1% 15 drops

With slow stirring, heat the salted gelatin in the 41°C waterbath for 1/2 hour.

Ammoniacal silver*: In a 50ml beaker.
Distilled water 10 ml
  Silver Nitrate 6.0 g
  Ammonium hydroxide, 28-29% 5.5 ml *plus

*Procedure: Thoroughly dissolve the silver nitrate in the water.  Under ventilation, with a dropper add the ammonium hydroxide slowly with stirring (Add a little. Stir about 15 seconds. Repeat.) A brownish-black silver hydroxide precipitate will form almost immediately. Continue to add and stir until the solution starts to clear a bit.  Slow down the addition rate to a drop at a time and stir longer between additions.  When you think all the little black flecks have dissolved, add one more drop of ammonia and stir thoroughly.  It is important to avoid excess ammonia. The total amount of added ammonia should be very close to 6 ml.

Fill a closed stopcock buret staged to be ready to move into position over the beaker of salted gelatin.

Plain gelatin: In a 50ml beaker.
  Distilled water, cold 15 ml
  Gelatin, photo
Gelatin, Knox
5.0 g
0.5 g


 Step One: Precipitation and Ripening

Set a timer for 1 hour.  Check to make sure the salted gelatin is 41°C.  (Keep the waterbath temp 40-41°C thoroughout entire 'step one'.)  Go to red safelight.  Move the buret over the beaker, halfway between the beaker wall and the vortex.

Begin rapid stirring in the salted gelatin and add half the silver solution. ("Rapid" is a good vortex without excessive splashing/air incorporation.) Continue stirring 1 min.  Stop stirring and ripen without stirring for 30 min.  Fluff the plain gelatin and, by hand with a clean plastic spoon, gently but thoroughly stir it into the emulsion.  Ripen without stirring an additional 15 min.  Start rapid magnetic stirring and add remaining silver solution.  Continue stirring 1 min.  Finish ripening without stirring for 15 min. Stir 1 min.  Pour the emulsion into a ziploc plastic sandwich bag in a pre-chilled lightproof container.  Refrigerate 2-4 hours.

Step Two: Emulsion Washing

 Under red safelight: Noodle the cold emulsion into a cotton jelly straining bag set in a thermos of cold water and crushed ice.  Pull the drawstring on the bag and tie tightly.  Secure the thermos lid. Tip the thermos back and forth for 5 minutes.  Do this six times, decarding the wash water each time, and then let the emulsion sit without agitation in ice water for 30 minutes.  Drain and replace the water two more times (3 total).   While the noodles are still in the jelly bag after the last washing, use the potato ricer (clean and dry) to squeeze out as much water as possible. Then, roll the bag in a clean, dry, cold terry towel and knead for a couple of minutes to get out more water. Open the jelly bag and sprinkle 8g dry photo gelatin over the top of the noodles and gently stir (the handle of a plastic spoon works well.) Don't worry about completely mixing it in.  Re-tie the jelly bag and replace it in the (cold and dry) lightproof container.  Hold under refrigeration (not freezing) for a couple hours to several days.

 Step Three: Digestion

Preheat a waterbath to 51°C. Preheat and hold a second waterbath to coating temperature.  Go to red safelight. Empty the noodles into a 400 ml beaker, scraping the cotton bag to get as much as possible.  Add 6 drops 10% KBr solution mixed with 5 ml Everclear. Stir thoroughly into cold noodles.  With several small additions with mixing, add 6 drops Steigmann's gold sensitizer (see below) mixed with 5 ml Everclear. Stir additional 2 min.  Set the beaker in the 51°C waterbath. (Maintain 51°C throughout.) Ripen without stirring for 15 min[Stir 1 min. Ripen without stirring 15 min.] x 3, for a total of 1 hour

Add finals**. Strain the emulsion into clean a 250 ml beaker. Cool with slow, gentle stirring to coating temperature. Set beaker in a coating temp waterbath (dry plates: 37-38°C;  film: ~32.5°C).


** Finals: Dry plates: 10 ml Everclear.  Film: 1 drop Photoflo 600, 3 drops Photoflo 200.


 Preparing a frugal amount of Steigmann's: Make a 1% solution of ammonium thiocyanate (2 g Amthio in 200 ml distilled water at 52°C/125°F, cooled to room temperature).  Mix 12 drops of 1% gold chloride with 5 ml of the Amthio solution.  Store at room temperature in a very small amber dropper bottle.

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