A real formula

[wildbillbugman]

Dear PE,
I don't mean to beat a dead hourse, I realy don't! But I am cornfused! When you wrote "Adjust gelatin leval to desired 5-10%"
You are saying : add more gelatin? Dry or in solution?
Perhaps I did make this in class. But I have never seen such an anemic emulsion befor. By anemic, I mean soft at 33F.
Bill

 

[Photo Engineer]

Well, Bill, under normal conditions, you should have a 5 - 10% solution of gelatin. If it takes solid gelatin, then that is what you have to add, but if not you can use up to 20% gelatin. If you use solid gelatin then heat the emulsion to 40 deg C and hold with the solid gelatin with stirring for about 1/2 hour. That will melt the gelatin and then you refilter.

IDK how you washed it. Noodle washing dilutes emulsion. You were going to use Jim Browning's formula last I read. That is a noodle wash. So, if this is too dilute by either method, you are doing something wrong.

PE

 

[Photo Engineer]

Please note in the OP that I suggest adjusting the gelatin to 5 - 10%. This can be done before or after the wash. It depends on method of wash and on the amount of dilution given to the original pot by the amount of ammonia used. I used household ammonia in one case and it was too dilute to set. I used 28% ammonia and it was just fine.

There are precise notes on this formula given to my workshop students in their notes.

PE

 

[Mahler_one]

Thanks...now I see why film is expensive...actually, when I read the instructions above, it is remarkable that film is as inexpensive as it is. I can only imagine how difficult it is to mass produce an emulsion to exacting standards over and over again....can you tell us, briefly, how Kodak manages to make a film like TMY to such exacting standards in darkness? Thanks.

Ed

 

[Photo Engineer]

Ed;

Emulsions are now made in huge batches by using automated equipment. Everything is controlled to the precise flow rate, temperature, time, and mixing rate (rpms and combined flows as well as adjusting turbulence during mixing). This is done under dim red light and sometimes with IR goggles.

Coating is done at precise rates in flow and throughput of support with carefully regulated chemicals.

The chemistry used involves up to 9,000 ingredients or more in one color film, all of which are tested for impurities before use, and the final products are tested at every stage of the operation. The emulsion is tested before coating and the coating is tested after the emulsion is dry.

I could go on, but only Kodak, Fuj and Ilford have the rigid specs for this fully worked out. All other companies use less rigorous methods. The one exception is the remnant of Agfa. Agfa once had the same standards and the remaining Agfa operations have been able to maintain most all of them.

PE

 

[Kirk Keyes]

You made it in class.

Bill - the formula at the start of this thread is very close to what we made in class. I looked in the handout, and as I measured out all the chemicals we used, I can tell you we made the 4x Scale of the Silver Bromoiodide VHS emulsion. It's almost exactly what's posted here - we used a bit more silver in the class - look in your class formulas handout to see how much.

The other difference between here and class is we let the one from class ripen longer than 2 hours. And we used phthalated gelatin so we could do an isowash on the emulsion in class.

From the couple emulsions I've made, I'd suggest swelling the gelatin with a little water (try about 1 part water to 1 part gelatin) before adding it to bring the gelatin up to the 8% or so conc. The times I've added dry gelatin, it seems like it just takes longer to get it to dissolve into the pot than when I swelled it with a little water.

Kirk

 

[wildbillbugman]

Thanks PE and Kirk,
The reason for my making the emulsion from this thread was that I wanted to start with a "bair-bones" emulsion for optimization of of sensitizers and hardener. Yes, I can and will do that with any emulsion formula. This one just "looked" very easy. I misinterpreted.
Thanks again,
Bill

 

[Photo Engineer]

Bill;

About 150+ grams of dry gelatin added any way you wish will bring the emulsion up to about the percentage you want. It is easy to calculate from the figures.

PE

 

[Mahler_one]

Thanks...thousands of ingredients, all tested for impurities...rather impressive I think. Did you omit some of the other manufacturers for cause, e.g., Adox, Foma, Bergger, etc.? Are the "less rigorous standards" reflected in the quality of the film? There have been occasional statements here and elsewhere about the problems with some of these films. Indeed, I know of several well known photographers who gave up using Bergger film because of the quality of the film.

 

[Photo Engineer]

I know how high the quality standards are of the companies I have mentioned. IDK about the others and so cannot comment. Except, as we see here on APUG there apparently are problems.

PE

 

[efranqueville]

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 50°C 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]

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]

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]

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 35°C, added the weight of gelatin to make it 7% of the final solution, hope that would fix the problem

 

[Photo Engineer]

The gelatin should set up overnight unless it falls below about 2% or if you heat it too hot for too long.

PE

 

[wildbillbugman]

If Google is God, is Yahoo The Devil ?

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]

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]

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]

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]

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]

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]

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]

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]

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]

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