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efranqueville
01-13-2009, 03:58 PM
Hi, I just tried this formula in a smaller scale (20x less) and I added almot 8ml of Ammonia (22%), wich gives me a brownish/dark solution is that usual or is there something wrong with the ammonia I m using ?
It became clearer, but not clear, so I decide to stop adding ammonia.
Once the solution had been added to salted A solution, the precipitate was white as usual.

Now it's in the oven a 50C in a water-thing (bain-marie), for the next 30 minutes.

Hopes this will work , it's my first type adding ammonia and using your formula, usually, everything worked fine but was verrrrrry slow (1/4 iso at best) :) .

Kirk Keyes
01-13-2009, 04:13 PM
The silver solution does turn brownish when you start adding the NH4OH solution. It should be pretty clear when you get more in.

Good luck, I'm sure you'll get more speed than ISO 1/4!

efranqueville
01-13-2009, 05:36 PM
Ok thanks ! now it's chilling waiting tomorow morning until wash, re-melt and adding gelatin to reach 7% :)

good day or good night :)

efranqueville
01-14-2009, 10:11 AM
as somebody noticed it before, after one night in the fridge , the emulsion is still liquid, maybe our gelatin are different ? To make washing possible I heated the solution at 35C, added the weight of gelatin to make it 7% of the final solution, hope that would fix the problem :)

Photo Engineer
01-14-2009, 10:12 AM
The gelatin should set up overnight unless it falls below about 2% or if you heat it too hot for too long.

PE

wildbillbugman
01-14-2009, 02:55 PM
The gelatin should set up overnight unless it falls below about 2% or if you heat it too hot for too long.

PE

OK,
At the risk of sounding stupid again-The formula,as written, has gelatin at under 2% from the gitgo. I have wondered if all that water is needed.
Bill:confused:

Photo Engineer
01-14-2009, 03:39 PM
Guys;

Please look at this thread from post #50 onward. In those posts we discuss this problem in detail. At some point in the make, you adjust the gelatin to 5% - 10% by adding solid gelatin or by adding 20% gelatin solution if that is usable.

Bill, if you look at the formula in your notes, as we discussed before, you will see exactly how this is done.

If the emulsion is too thin to set up, add the gelatin before the wash, if it sets up add the gelatin after the wash. You are all missing that crucial line. Now, the reason for the order of adding the gelatin is this. If you noodle wash and make it 10%, it can become too hard to run through the noodler, so you can add some gelatin before and some after the wash.

You have all apparently forgotten the early parts of this thread, the details of the OP and the exact instructions in the workshop notes.

Sorry.

PE

Kirk Keyes
01-14-2009, 10:52 PM
PE - in post #52, you write, "Please note in the OP that I suggest adjusting the gelatin to 5 - 10%. This can be done before or after the wash."

In the original post, adding gelatin is listed as the step after the wash. It looks like before the wash would work better for most people.

Photo Engineer
01-15-2009, 08:16 AM
Kirk;

You are right and it depends on the gelatin and how well it sets up. Personally, I have found it works best before the chill set. I add as you said earlier, at the start of the heat set. I use dry gel to avoid further dilution. I also gave the amount of gelatin that I added.

The strategy is this: Low gelatin promotes formation of large grains for speed. Adding gelatin protects during further heating and I have found that it helps to be there during digestion.

PE

wildbillbugman
01-15-2009, 01:56 PM
Hello PE,
My fears have been realized! My last post dose make me look stupid. But your last post finaly passed through my skull and I do understand that a lower viscosity promotes grain growth.
Humbly,
Bill

EASmithV
01-15-2009, 04:35 PM
Do you have any examples to show? I'm interested in seeing what the grain is like. One would think that a slower film would have better grain... but having used copy film I know better.

Photo Engineer
01-15-2009, 04:54 PM
Do you have any examples to show? I'm interested in seeing what the grain is like. One would think that a slower film would have better grain... but having used copy film I know better.

I have posted quite a few here, and at the risk of using up Sean's storage space, I guess I can do it again. Left is an ortho sensitive version of the emulsion in the OP, using PA gelatin and ISO washing. The sensitizer was Erythrosine. The right image is a Scanning Electron Micrograph of the emulsion. The results in this case are independant of whether Dye is added or regular or ISO washing is done. I have checked them out with SEMs also.

PE

efranqueville
01-18-2009, 12:08 PM
PE, everything have been fine, as you said I just added the gelatin before washing few days ago, not a big deal ;) , now I m waiting for time to try the 4 4x5 glass plate I coat with Osterman's method (I also do Wet plate).
I m very busy at work nowadays but hope to sho few samples in the next days

Ok I did a few test just to know, and my emulsion is completly foggy, I hope it comes from the drying box I use (color paper transporting box to RA4 developping machine), but I m not sure maybe the whole batch is over, I m using a yellow light and I hope it will not come from that, I will give another try in better condition.

By the way, what are your recommandation for processing this emulsion ? I used a paper developper (Agfa Neutol) at 1+4 because I add problem with ID11 (peeling in the fix bath), I used to make my own but had not enough component for now so ..

totalamateur
10-20-2009, 01:05 PM
I made my first emulsion in a long while last nigth, using this formula, and I have a couple of questions:

1. when I diluted the AgNO3 with Ammonia, it turned brown, as I expected, and as I added more, it turned darker and darker until it cleared up, leaving a brown precipitate at the bottom. The precipitate looked suspiciously like silver. Is this normal, or do I need to get a different bottle of ammonia?

2. My hot plate is in capable of holding a temperature under 130 degrees F. what effect on crystal growth will this have?

3. even in a chilled ice bath, my noodle wash caused an increase in volume, about 10-15%, using about 8% gelatin. The resulting emulsion afterwards was not terribly stiff (Bloom 250 photo grade gelatin). Is there a temperature at which photo gelatin breaks down?

Thanks for the help.

Photo Engineer
10-20-2009, 01:14 PM
Here are some answers:

1. If there is a brown or black ppt at the bottom there may be 2 causes. One is not enough ammonia and the other is that the Silver Nitrate is old or low quality. If adding more ammonia does not clear up the brown ppt. then the Silver Nitrate is not very good.

2. As temperature goes up, crystal size, fog and speed generally go up. You can offset this by shorter hold times at a given temperature in some cases. As temperature goes down, the crystals go down in size, fog and speed decrease.

3. I use 4 deg C for my wash. Volume generally goes up. You can add some 20% gelatin to this to stiffen it up, but you usually have to coat a tad more emulsion per unit area to offset the dilution.

Gelatin can break down at any temperature if the pH is too high or low and it can break down at any temperature with a long enough hold time. I try to stay below 80 C and preferrably at or below 60 C for these makes. I try to keep holds at or below 1 hour and the Ammonia digest is probably not alkaline enough to cause a probem with these conditions.

PE

Photo Engineer
02-08-2011, 09:07 PM
Silver halide is sensitized by adding thiosulfate at 1 - 100 grams / mole of silver present. Unfortunately, this level is based on grain size (surface area actually) and therefore unless you have electron micrographs you have to determine it by trial and error.

Gold is used a 1 part of gold salt / 3 parts of thiosulfate.

Don't use Dichromate.

PE

As a very kind person has noted, this post should read Thiosulfate is added at the rate of 1 - 100 mg / mole of Silver present. And it is based on Sodkum Thiosulfate Pentahydrate.

Sorry for this mixup.

PE

kb3lms
12-14-2011, 02:28 PM
Add 28% ammonium hydroxide to B with stirring until a clear solution results.

PE,

At this point, how much ammonium hydroxide is used? I am ordering materials from the Formulary and want to make sure I get enough. Would I be correct in understanding that it is a fairly small amount?

Thanks!

hrst
12-14-2011, 08:42 PM
For me, it was around 20% of solution B volume.

Photo Engineer
12-16-2011, 02:25 PM
PE,

At this point, how much ammonium hydroxide is used? I am ordering materials from the Formulary and want to make sure I get enough. Would I be correct in understanding that it is a fairly small amount?

Thanks!

It really depends on batch size.

I use about 25 ml of 28% Ammonium Hydroxide for about 250 ml of emulsion, but this depends on quite a few things such as the "real" concentration of the Ammonia solution. It is subject to changes due to evaporation of NH3 gas. So, I order about 250 ml at a time and it lasts me for about 5 - 10 batches depending.

PE

kb3lms
12-16-2011, 08:15 PM
Thank you for the info. Well, I have off between Christmas and New Year's so I am looking forward to making my first run soon!