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hrst
09-18-2009, 03:26 PM
Hello,

Today we started making an emulsion for a first time. It's now standing in room temperature over this night, and tomorrow we'll proceed to noodle wash. If you don't mind, I'll post our process here just to make sure it's okay and maybe get some tips :).

First, I started by making silver nitrate. Silver should have been pure and nitric acid was 60% laboratory quality. I evaporated all the nitric acid, added distilled water and evaporated it. Still, it wasn't 100% white but a very little gray and smelled a little (some residual nitric acid?). I hope it's okay...

We followed the formula in PE's topic "A real formula", but made only 1/10 of it. We substituted 11,41 g of sodium bromide for 13,2 g of potassium bromide. We used food gelatin, not powder but "sheets". It doesn't say anything about additives but that it's made from pig skin.

We heated silver nitrate solution (B) to about 45-50 C and added ammonia. First it got yellow, and then completely clear. It took maybe about 5-20 ml of ammonia for 50 ml of B. (Didn't measure though.) Oh yeah, looking good at this point!

We heated A on hotplate magnetic stirrer to 45C and B to 45C in water bath.

We started adding B to A, about 5 ml at a time, every minute. It took 12 minutes to do this. B wasn't in water bath any more so the temperature dropped. But the hotplate stirrer has a sensor so it keeps the emulsion at 45C all the time.

After B was added, we kept emulsion at 45C for 30 minutes, keeping the stirrer going. Shut down the safelight for this time.

Then we poured emulsion to five 35 mm film containers. We left three of them to room temperature, about 25C, and two of them in refrigerator at about 10C. It takes some time to cool down, because we put the film containers in a plastic processing tank (because it's lighttight).

Tomorrow, we are going to add gelatin if necessary and noodelize some emulsion, wash (until wash water shows no crud when added some silver nitrate), and add gelatin. No sentisizers yet. Right?

And then coat some overhead projection transparencies (not the laser-ones but the cheapest ones, they are perfectly smooth like film base, I think they are acetate). We made a simple coating blade with about 10mil gap.

Now, is everything going well? At least it was very fun! Any tips & tricks for tomorrow?

I poured some emulsion on OHP transparency and dried it with hairdryer, then exposed to light and developed in paper developer. It got black! So it basically seems to work. But it needed much light.

I'll post results.

I've extracted some chlorophyll from leafs using acetone, we are going to experiment if it could be used as red sentisizer. But there will be so much to do before that point... If we can even get a decent blue-sensitive emulsion first!

PS. HUGE thanks to PE, your information about emulsion making here is priceless!! Thank you thank you thank you.

Ian Grant
09-18-2009, 03:36 PM
The storage temperatures are important. Overnight at room temperature with no additives is a potential problem.

Something that I've not seen mentioned at all on PUG is the importance of digestion/ripenening times & temperatures, these can make a very significant difference to the speed & contrast characteristics of an emulsion.

Ian

Photo Engineer
09-18-2009, 03:47 PM
Have fun.

Make sure that the emulsion has set up to a gel before you noodle it, and use cold water. The whole process should be carried out at under 20 deg C, usually about 10 deg C. to keep the noodles from swelling too much. Wash free of ammonia odor and as much residual salt as possible and adjust the pH to about 6.0 with dilute sulfuric acid (3 - 30% max) if it is still basic. If it becomes too acid, below 6.0 then use 4% sodium hydroxide to bring it up to about 6.

If you don't harden the coating, you will have to preharden with formalin solution or chrome alum solution.

PE

Photo Engineer
09-18-2009, 03:50 PM
The storage temperatures are important. Overnight at room temperature with no additives is a potential problem.

Something that I've not seen mentioned at all on PUG is the importance of digestion/ripenening times & temperatures, these can make a very significant difference to the speed & contrast characteristics of an emulsion.

Ian

Ian;

This particular SRAD can use up to 1 week at 4 deg C for digestion and / or a digest of 1 hour at up to 50 deg C or a digest of 4 hours at RT. So, it is quite robust in this sense.

The time and temperature will affect speed and contrast though.

I would add that with food grade pig gelatin, I have no idea what they will actually get. This formula was designed for photo grade inactive bone (cow) gelatin.

PE

hrst
09-18-2009, 04:35 PM
Thanks for answers. Yes, I'm very interested about this gelatin, whether it will work or not -- of course it would be cool to be able to use basic, non-photographic ingredients that are easily available also in smaller countries. And I'm also interested about how much it has sulfur, so what ISO we will get without hypo. I will definitely post results in any case!



If you don't harden the coating, you will have to preharden with formalin solution or chrome alum solution.


I found from some post here that 0.125 g chrome alum would be about right for 160 ml of emulsion. But if I get formalin, how much should I use it, and how concentrated?

If I coat medium format roll film, maybe I should add an overcoat also? Is it done after drying the first coating for, say, one day at RT? Is it just gelatin + formalin or chrome alum?

Now, am I right that hypo (and possibly gold chloride) is added after noodle wash? Is it done before or after gelatin level fix?

Thanks a lot for helping us out!

Photo Engineer
09-18-2009, 05:02 PM
If you preharden in a bath before the developer do the following:

10% Chrome alum OR a formalin bath as follows:

Formalin 37% 10 ml
Sodium Sulfate 50 g
Sodium Carbonate 50 g
Water to 1 L, pH 8 - 9 with NaOH or H2SO4 (4%)

Treat coating for about 5 minutes in either of the above hardeners and then wash for 5 mins at 20 deg C, then go on with your normal process.

Do the hypo + gold after the wash and gelatin addition. Pig gelatin will offset any figure I might give and so it will probably have to be done by trial and error. Sorry.

I don't suggest that you coat roll film. Coat sheet film or plates.

PE

hrst
09-19-2009, 06:54 PM
Today we started where we left yesterday: first half, digested in room temp overnight; and second half, digested in refrigerator overnight.

We melted the emulsion and proceeded to noodelization (nice word huh?? :p). We found out that it required about 13 g / 100 ml of food gelatin to become proper gel for noodeling and the final level was about 15-16 g / 100 ml to coat properly. That's quite a lot, isn't it. We had to heat and cool down the emulsion many times before we found this gelatin level, so maybe there is too much digestion now. The second batch went better, though, as we knew this high gelatin level.

Maybe this pig gelatin is needed in larger amounts. Maybe I should change the starting point also, eg. 30 g/l --> 60 g/l.

We washed for about 40 minutes and, still, wash water sample showed some deposition with silver nitrate test solution. We decided to stop washing at this point. When melted again, it had a little ammonia smell, but not much. I think our noodles are too thick (about 5 mm) and thus wash slowly. Have to get better noodler. As we didn't have an access to a pH meter, we didn't do any adjustments now...

We coated the first half that was in room temperature overnight. No sentization. After coating, chilled for a minute or two in refrigerator and put to room temp. Not quite uniform yet. But the third one started to look good! I think we'll learn it by doing :).

We also washed (but not coated yet) the second half that was in refrigerator overnight and divided it into three further batches: A) no sentization; B) 9 ml of 1 g/l hypo per 100 ml emulsion; and C) 25 ml of 1 g/l hypo per 100 ml emulsion. For every batch, we added the hypo solution and then stirred for 3-4 minutes. We put these in 5 C refrigerator and we will coat them on Monday. I hope it keeps until that.

Emulsion splashes on the table were beautifully yellow and got very black quite quickly when we poured some developer on them!

And, what's best, it was very fun again! If you don't mind, I'll continue posting to this thread about our experiences. Many thanks for tips and for bearing with us,

Antti Alhonen & Matti Hautala
Finland.

Photo Engineer
09-19-2009, 07:15 PM
Well, firstoff, gelatin comes in grades indicated by Bloom Index. There is a rough correlation between BI and viscosity. Food gelatin is low in BI in most cases, around 75, while Photograde is around 250. This means that Photograde would be more "chewey" if you ate it. :)

So, you may need more gelatin to get to the best coating point.

Next, you cannot test for halide presence or salt presence when the emulsion is still alkaline. You will get Silver Hydroxide and also other Ammonia complexes of Silver, so you either have to make it acidic with H2SO4 first or wait until the ammonia odor is gone. Otherwise, the test will fail.

Lastly, I cannot help you with the hypo level at all, but what you gave sounds high to me, but then you are not heat treating the emulsion so IDK what will happen.

Best wishes.

PE

hrst
09-20-2009, 09:18 AM
This hardening thing still seems like a mystery to me... I've read dozens of threads here in APUG during last weeks but everything is mixed up in my head and it's difficult to find the information again.

So, let me rephrase: there are at least three different things:

1) A subbing layer, that may be needed for adhesion of emulsion. Includes chrome alum or formalin?
2) Hardening of the emulsion itself. If made with formalin, takes some time to harden and can fog if kept for too long. Formalin was used in films decades ago?
3) Overcoat that protects emulsion. Needed if film is wound up on a roll. This also includes chrome alum or formalin?

Hardening of emulsion is compulsory, sub and overcoat only if needed. And, hardening can be omitted if emulsion is hardened after exposure, before processing, and that is called prehardening. Am I right at all :confused:?

Can I add that formalin hardener to the emulsion just before coating? How much I should add it? I have understood that it may fog the emulsion if not coated right away. How about coated film if not exposed right away, how quickly it will fog? One day? One week? One month? One year?

Thanks,

A.A.

Photo Engineer
09-20-2009, 09:51 AM
You havae things essentially correct, but.........................!!!

I use glyoxal as it is less toxic.

You add the hardener just before coating. You must begin coating then. It will harden if not coated right away. After coating, fogging is slower but depends on the emulsion.

You may leave out hardener and then use a prehardening solution (given in my post above) just before the developer as follows:

Preharden
Wash
Develop
Stop or rinse
Fix - hardening fix suggested
Wash
Photo Flo if film or glass
Dry

hrst
09-20-2009, 10:44 AM
Thanks!

I remember reading somewhere that formaldehyde could be used at 0.1 % of gelatin mass. Right?

For 16 grams of gelatin, that would make 16 mg of formaldehyde, that is, 43 milligrams of 37% formalin solution. Is it really this little?

Does the same figure work with glyoxal?

And, finally, if I can't find formalin tomorrow, can I try replacing it with Jobo E6 Stabilizer/final rinse (it includes formalin)? -- or do you know that the wetting agent would be a problem? The 250 ml concentrate makes 5 l of stabilizer, so the concentrate has quite a high formalin content. I could calculate the formalin concentration by comparing to E6 stabilizer recipe.

Photo Engineer
09-20-2009, 10:58 AM
Well, I use 0.5 ml of 4% glyoxal (that is commercial 40% diluted to 4%) in every batch of 100 ml - 200 ml of 10% gelatin. This is the usual range. For chrome alum, I use the same 0.5 ml, but it is a 10% solution. Hardening is good enough for processing in about 24 - 48 hours.

E6 stabilzer that is currently on the market made by Kodak does not have formalin and the photo flo present will mess with the coatability. Other companies make a stabilzer with formalin and it would work, but again the photo flo (surfactant) will affect coatability. The only answer is to try it out.

PE

hrst
09-21-2009, 11:55 AM
Now we tried it out. The one half that was digested in room temperature (no hypo sensitizing) and coated two days ago. Dmin is very low (no fog), that's good, but... It seems something like 0.01 ISO and Dmax is maybe about Dmin+0.1 so very very low contrast. We exposed a 6x6 frame at f/2.8 20 seconds in bright sunlight, no visible image at all. Just clear film. With enlarger we could get some darkening but contrast is very very low.

The second problem was that emulsion loosened. We couldn't get formalin or chrome alum, and E6 stabilizer didn't harden it :p. But our emulsion was hard enough that it survived the process even when it loosened. Maybe we need a subbing layer or different support material... Or wait more to allow it dry better. (EDIT: Or, can bad noodle washing be a reason too? This was the first batch we washed only about 20 minutes and noodles were over 5mm thick.)

But, our coating seemed quite consistent and good.

We used XTOL 1+1 as developer, then we made a cocktail (added some hydroquinone and rodinal to it) to try to increase contrast...

Now, when we get some hardening stuff, we will coat the hypo-sensitized emulsion. I really hope that it shows more contrast and better ISO...

We didn't really get any image at all now.

I have some ideas, like:

- This food gelatin is very inactive and sulfur sensitization is really needed, which would explain very low ISO and very low contrast
- Our emulsion is not thick enough, thus low DMAX? (It seems good to me, but...)
- Our developer cocktail may have some restrainer to control fog with real films? Maybe we should use metol-HQ paper developer (Dektol?) to get better contrast?

And some questions:

- Can noodle washing wash silver halides away?
- Can remaining ammonia affect the results?
- Anything else that comes to mind??

Help :(.

Ray Rogers
09-21-2009, 01:18 PM
contrast is very very low... emulsion loosened... We didn't really get any image at all... Anything else that comes to mind??
Help :(.

Nice to see some real results for a change!

emulsion loosened...
You should test plain gelatin with your base till you get that down.
(What base was it?)

wait more to allow it dry better???
Oh YesYes... or talk to Ian about processing while wet :D

Our coating seemed quite consistent and good...
Wonderful! How was it done?

We didn't really get any image at all now...
:o

Sulfur sensitization is really needed???
yes and no

- Our emulsion is not thick enough, thus low DMAX?
Could be true, but it sounds like you have more troubles than just that...

- Maybe we should use metol-HQ paper developer (Dektol?) to get better contrast?
Worth a try.

- Can noodle washing wash silver halides away?
A very small amount will be lost,
but it will not be necessary to "cry over a little spilled milk"!
Don't be afraid to wash well... especially behind the ears ;)

- Can remaining ammonia affect the results?
  Oh yea.

- Anything else that comes to mind??
Same answer!

Don't think too much right now...
Go finish the testing with the sensitized emulsions and then compare.
You will have plenty of time for thinking then.

Photo Engineer
09-21-2009, 03:37 PM
Sulfur or sulfur + gold will raise speed and contrast.

I can't help you out with food grade pig gelatin. Not enough information.

I use Dektol 1:3 for 3 + minutes or D-76 for 11 minutes.

Sorry I cannot be of more help.

PE

hrst
09-22-2009, 04:13 PM
Oh yeah, made a new coating with sulfur-sensitized stuff and adjusted the blade gap to make a thicker coating. The problem really was too thin emulsion, I think:

We were afraid of too thick emulsion because of too low gelatin at first (which made coating thick difficult) and because of huge weight of the wet emulsion. But of course it loses water when it dries and starts to resemble normal film! The first coatings indeed were almost transparent even before processing.

Not tested the ISO yet (we let it dry first) but now the Dmax seems something like 2.0 rather than 0.1! Maybe the sulfur sensization helped too but with this coating I really see the difference between thin (very low Dmax) and thick emulsion. Now the fully fogged test strips also develop faster to Dmax, 20 seconds in Dektol 1+2 rather than 2-3 minutes. Sulphur?

Oh la la!

I'll post the results...

Ray:

What base?
- OHP film, not for laser but for hand-writing (smooth unlike the laser films).

How coating was done?
- We made a blade that resembles PE's blade a little. Not so good, I guess, because PE's put a lot of effort but ours is just one day's work, but seems to work for us, for now. It has two 2x2x10 cm stainless steel sticks that are heavy to keep it stable and a thin stainless blade (polished carefully, finished with aluminum oxide polishing) between them, mounted with screws so the gap can be adjusted.


-AA

Photo Engineer
09-22-2009, 06:10 PM
Any film intended for use in digital printing is probably going to cause problems. The mordant in the coated side can be a real pain and absorb the wrong things.

PE

hrst
09-22-2009, 09:22 PM
Yeah. I actually bought these OHP films to use them as animation cels (that's an another interest of mine :D) -- tracing the line art and them painting them in acrylic, and then film them in 16mm. I built an animation stand for that. That launched my interest in motion picture film, MP film processing, film processing in general and that way I was suddenly interested in making some film. Now I've almost forgotten the animation :rolleyes:...

Overhead projector films you can get from most sellers are for laser printers (less expensive) or for inkjet printers (much more expensive). Both of them have a special surface that helps the toner or ink to adhere, and, in addition, they discolor in no time. The mat surface lowered the contrast too much for animation camera work so I had to find a cheap alternative with no surface treatment.

It took some effort to find these traditional, cheap "hand-writing" films with unprocessed surface. But it's probably not acetate, it's harder (like polyester). If they are really polyester, I'm lucky.

One source for cellulose triacetate sheets could be Chroma Colour. They sell animation cels that are triacetate:
http://www.chromacolour.com/store/triacetate_cel_ca.htm

hrst
09-23-2009, 05:12 PM
Yeah, now it works. Problem was way too thin coating. Now we get the same speed, about ISO 10, with all three emulsions with different hypo content, probably because we forgot the heat treatment after adding the hypo (it was just 2-3 min at ~40C). Fog is low and Dmax is high, contrast seems very good. I'm very happy about this emulsion!

But, the emulsion doesn't adhere to film base. It loosens in processing or even before. We have no hardening yet because we couldn't find a quick source for formalin, glyoxal or chrome alum but I think that's not the only problem. Maybe we need a better base or a subbing layer.

I attached an example. I dropped this one on floor (emulsion down, of course!) before exposure, that explains the white dust :D. Emulsion was loosened as you can see. But, the contrast and speed are OK! This one is in fact the not hypo sensitized one.

Big thanks PE and Ray for tips!

Photo Engineer
09-23-2009, 05:22 PM
Congratulations. Looks better than some of mine! :D

Do you have any speed estimate compared to paper or film?

PE