Noodle Washing and Fog Question

[kb3lms]

A question about the completeness of washing. Every emulsion I have made goes into fog rapidly after about 40 minutes of digestion. Book references I see for similar formulas often talk about one to two hours. The current one I am working on specifies 55 to 60 minutes @ 55C. Sensitization has been using Steigmann's gold solution mixed per instruction on "The Light Farm".

Washing is done in ice water with some ice cubes in it inside of an insulated cocktail shaker. My noodles aren't so much noodles but more like large crumbs due to the device used to shred.

Per a suggestion by Duffin*, I have added 1 teaspoon per gallon of Magnesium Sulfate to reduce swelling. However in the last emulsion I made, I specifically left out the MgSO3 and it made no difference. Washing time is two hours, give or take a few minutes.

Knowing that leaving too little excess bromide in the emulsion can lead to fog, could the fog be coming on more quickly than expected because of over (or under) washing? Other things I might want to look for?

The 40 minutes has been consistent regardless of exact emulsion make which is why I am thinking about washing procedure. Maybe this is even a non-problem?

-- Jason

* In "Photographic Emulsion Chemistry"

 

[dwross]

Hi Jason,

A couple of things.

Yes, fog is possible from both under and over-washing. Best to wash very thoroughly and then return a little KBr after washing. It's basically the same principle as using inert gelatin and then adding just the sensitizers you want. Takes a lot of unnecessary randomness out of the system.

Magnesium sulfate or other chemicals to reduce swelling are to make sure the gelatin doesn't absorb so much extra water that it throws off the concentration of the emulsion. Distilled water is a surefire "sweller". That's the reason it isn't recommended. The original emulsion factories were deliberately located where there was good natural water. Using distilled water with just the right pinch of just the right minerals is a work around against bad water.

But, here's something I figured out this summer. Chlorinated water is poisonous to emulsions. Until this summer, I've had great tap water. Our drought changed that. The reservoir drew down so low the water company had to add increasing amounts of chlorine to the water. I didn't detect it in the beginning. All I knew was that I was having the first fog problems I'd experienced. When the chlorine got high enough to really smell, I had my 'aha!' moment and started using bottled spring water for washing. Fixed everything.

I am concerned you aren't washing your emulsion enough. A cocktail shaker isn't much volume, especially if you aren't changing your water enough, and if your emulsion crumbs are so large that the salts in the center aren't diffusing out to the surface and into the wash water.

So, try to wash very well, with bottled natural spring water and plenty of it and ice, and then add back some KBr solution. One or all of those will bust your fog problem. Might as well do them all and simplify and standardize your washing. Simplification and standardization are your very good friends.

 

[kb3lms]

Thanks, Denise. My washing procedure is right down the line of the instructions you gave me for TLF 2. However, the idea of not enough water volume might be a problem. I have a much larger thermos jug handy and will try that. Will also figure out a way to shred the crumbs more finely. Maybe I will cut up this batch with a sharp knife instead tying to shred it.

We have well water, so no chlorine, but it is quite hard with calcium and lots of iron. (A broken rock in my back yard will rust within hours.) Been using DW wash with the MgSO3 and that works nicely with regards to swelling. The ice I use is from our well water but I never have to use all that much. Have not thought about trying spring water. Maybe I'll pick up a couple gallons tomorrow.

One thing that tipped me off to washing is that various sources I have read talk about washing times of 3 to 6 hours in running water. I am only at two.

How are you washing these days?

 

[Photo Engineer]

Jason, your wash is far too long and will promote fog. I never wash over 1 hour and often much less depending on how fast the halide level drops. I test it with a Silver Nitrate solution to see if there is any residual halide. I always break off before I wash all of the halide out! You can always put a bit more back in, if you go too far, but sorry to say that fog, once formed, cannot be made to go away unless you use an antifoggant. Antifoggants in order of increasing potency are KBr/NaBr, TAI, PMT. And remember that antifoggants always cause some degree of speed loss.

We used conductivity or pAg as a measure of completion of wash. Since this is rather complicated, I have refrained from discussing it here. Just remember that when you want to go further there are other things waiting in the wings.

PE

 

[dwross]

Jason,
Thanks for the additional details. Oy, iron. Glad you're not using much well water. I really would recommend you switch to spring water. I use "EartH20", labeled 100% natural spring water. It comes from an Oregon spring, but I imagine every region has its own, great brand. You don't want anything labeled 'mineral water'. I only pay $.99 a gallon, so considering the cost of silver and time, it seems a bargain. I also use bagged crushed ice. (Tillamook brand) I use a LOT of ice. That guarantees the wash water is the same temperature at all times, not matter the time of year. My goal has always been simplification and standardization. That makes it easier to spot problems that come from changes in ingredients that you don't personally control. Everyone needs to work out their own protocols for their own work habits and working situations.

Washing emulsion is all about diffusion, plain and simple. You can imagine the possible scenario in your situation. Your wash water volume is too low. The initial leaching of salts near the surface of your crumbs immediately goes into the wash water at a fairly high concentration. That makes it even harder for the salts at the center of a too-large bit to diffuse out.

I use a stainless steel potato ricer. My bits are very small. I wash for six water exchanges in 30 minutes, agitating the thermos the whole time,completely dumping the used ice water for new each time and giving the bag a squeeze before putting it back in the new water, followed by one good 30 minutes soak, without agitation, for plain silver emulsions, and three x 30 minutes for ammoniacal emulsions. All I can say: I get great, clean, consistent results. Have been for years.

I understand that not everyone can find potato ricers. Kitchen tools change with the times like all other tools . A parmesan cheese or chocolate grater works well, though. I'm playing with one so I can feel confident recommending it. I'll post something on TLF sometime this week.

 

[Photo Engineer]

Iron can cause fog.

Beware of plated materials or cheap stainless. They can corrode and expose the underlying metal which may be iron or something worse.

PE

 

[Hexavalent]

....
The 40 minutes has been consistent regardless of exact emulsion make which is why I am thinking about washing procedure. Maybe this is even a non-problem?

Another though: Is your emulsion exposed to safelight for that 40 minutes? Any stray light, or less than ideal filtering will fog an emulsion. Been there, done that.

 

[dwross]

Good one. Boo to the "red" safelights that are really white bulbs with red paint! The paint almost always gets little chips for the white light to escape through.

Jason, may I suggest you leave out the Steigmann's for one batch and see how that works for you (along with the washing and stray light suggestions.) It increases speed, but too much can cause fog. If that emulsion is fog free (and btw, nothing wrong with a little baseline fog in negatives) add in Steigmann's additively one drop extra at a time with each subsequent batch you make. At some point, you'll see more fog than you've been seeing. Go back to the number of drops in the last batch before. You should be at the optimal sensitizing point for the recipe, as made by you in your conditions.

 

[kb3lms]

Thank you, everyone.

Here's my answers to your questions.

1) All my safelights close to my work area are either Red LED or the Kodak type with a red filter and I have tested all of them with photo paper. They haven't given me any problems so far. I stay away from the painted bulbs just because of the chip problem. I have some red Christmas light type bulbs at the other end of the basement but they are over 25 feet away. Mostly, though, I turn off the safelight whenever I can. Regardless of the spectral sensitivity I figure less light is less light.

2) Thank you for the tip about the AgNO3 solution, Ron. I have just changed water after the first 30 minutes and 3 drops in about 100 ml of the wash water was very cloudy. I'll wash till there is just a little "cloud" left from the AgNO3.

3) Everything I use for precipitation and digestion is glass, because it is convenient and stays away from metal problems.

4) I can leave out the Steigman's this time. It is a new emulsion (to me) anyway, so maybe 1 run without the Steigman's is a good idea both because of fog and to get an idea of the base speed.

5) As I mentioned above, my wash water is always DW (83 cents a gallon) with one teaspoon MgSO4 added per gallon. I don't trust my well water with all the minerals in it. Trying spring water is no problem. I am not worried about the small cost of the water.

This emulsion is neutral, which I haven't tried before. My inspiration was the P30 formula posted over in the Ferrania thread. No, I don't intend to recreate P30 - it just got me moving again.

Great to see everyone still in here! Hope you guys are still making too. Thanks for all the help so far.

-- Jason

 

[Photo Engineer]

Well, since time and temp are the variables in sensitization and the sensitizing solution is "supposed" to be constant once determined, you might get some blotting paper and an eyedropper. Do everything you are now doing up to the sensitization step and then every 5' remove one drop and place it on the blotter in a row. At the end when it is foggy, just stick the blotter strip into your developer. The appearance of fog will tell you the right time. Do this with varying temp and varying sensitizing solution and then compare the results for the optimum. This factorial experiment is called a "Breakdown" in Kodak parlance.

PE

 

[rwhb12]

Just to say that my Ebay (from Hong Kong) noodler (ebay 121405993186) worked a treat and was cheap.

You guys have great water prices! A gallon on DW is around $7.50 and spring is $2/quart. I now have my own 1979 made double glass DW still....and a very understanding wife who allows it to stand next to the sink in the kitchen!

russ

 

[kb3lms]

Breakdown, etc.

I like your breakdown idea, Ron, with the blotter paper and will try that. In the past I use glass microscope slides which work, but the paper idea seems easier to do.

So, 7 changes of water got the emulsion to the point where 5 drops of AgNO3 in 100ml of wash water produced just a little cloudiness. I stopped there. This was 3 1/2 hours as each water change was 30 minutes. Now, I believe I will take a small portion of the emulsion and try to digest it to find where fog starts to show up. Then back off 5 minutes or so and start with that as the planned digestion time. The formula says 55 to 60 minutes at 55C. We'll see if that works out.

Tonight and tomorrow night I have other things to do so I have a couple days to think about this.

Ron, when you have a chance, I would appreciate if you could elaborate a little about how washing progress was measured by conductivity of the wash water. I have read about it being done but don't know how it works.

The P30 formula gives a measurement but without knowing how this would be done I have know idea what the measurement means. And, of course, we can only guess how Ferrania actually did this. Again, not so much attempting to duplicate a P30, just to follow the general idea, with a generous helping of educated and un-educated guesses!

 

[kb3lms]

A gallon on DW is around $7.50 and spring is $2/quart.

Isn't that about what gas/petrol costs you guys? Ouch! What's with that?

 

[pdeeh]

hmm, I can buy DI in my local supermarket at £2.30 for 5 litres, which according to google is $3.65.

I can buy petrol at the same supermarket and it costs about $2/litre

As you have weird gallons and pints and quarts over there, I'll leave it to you to work out the equivalences

 

[NedL]

We're lucky here, a gallon of DW is less than $1. Lately I've been using a lot of it. The empty containers are also useful to keep discharges that have to go to the hazardous waste facility.

All this talk recently on the emulsion making forums has made me go read through TLF again. I keep going back to Kevin Klein's recipe. I love blue-sensitive photos with atmospheric haze where you can see the "density" of the light-filled air. Modern film and UV filters knock that way back, losing the "aerial perspective". It's one reason I like paper negatives so much.

Well, I've already got all the ingredients for this emulsion here. All I need is some glass plates to try it on, and a way to shred the emulsion for washing. Would an emulsion like this one also be usable on paper?

I also don't have any thymol and I don't see it for sale at Photographer's Formulary or Bostic and Sullivan... have to look around...

I've been eyeing this potato ricer, do I need to worry about low quality stainless steel? Will it work? Should I look for a plastic one?

 

[pdeeh]

I was looking for thymol over here (to keep my cyanotype chemicals from going furry) and found the place to buy it was from beekeepers/apiarists' suppliers.

(GCK says you can slosh a bit of Listerine original into Ferric ammonium citrate solution to keep it fresh, but I imagine that might bugger up a proper emulsion )

 

[NedL]

Thanks pdeeh, we have a beekeeper's supply nearby, I'll check with them.

 

[kb3lms]

Ned, Thymol is a preservative to keep bacteria from growing in your emulsion during extended storage. You don't have to have it. Emulsions will keep for months without thymol although I am sure they keep much longer with it. My thymol comes from the formulary. I've also seen it listed on eBay although I have not bought any through that path. If you are going to make your emulsion and coat your plates within a few weeks you can easily get away without the thymol.

You can shred your emulsion for washing with a sharp knife just as well. A potato ricer is not strictly needed. I don't have one. Any way to cut up the gelled emulsion into small pieces will work. I guess a potato ricer is ideal for the job, but I have never found one at a price I was willing to pay. All you need to have is the emulsion cut into small pieces so the bromide can diffuse out into the wash water.

Staying away from poor quality stainless for anything that will contact the emulsion for an extended time is probably a good idea.

Jason

 

[NedL]

Thanks Jason!

Now I have no excuses at all! Just need to visit a glass shop.
I was thinking if could get a batch of 2mm glass cut to 3-3/4 x 6 inches, they would fit directly into my kodak 3A, and that might be a fun place to start.

Ned

 

[Photo Engineer]

Several answers to give here:

Conductivity is measured with any pH meter set to the proper setting. OTOH, if you have a normal VOM from Radio Shack for example, just set it up with the electrodes and select resistance. Conductivity is the reciprocal of resistance. I use vAg or pAg and can give details on this, but it is complex and requires special electrodes.

The Chinese potato ricer went bad after about 6 months. The plating began peeling and the iron underneath began to corrode.

The potato ricer shown above that was lever operated works fine. I use one exactly like it. However, don't squeeze too fast or too hard or emulsion ooozes up around the edges. The plunger is not a tight fit.

Thymol is getting hard to buy. You have to buy it in large quantities. I am working on a replacement that is up to 40x stronger than Thymol. We used it at EK. In the mean time, Listerine is ok to use, but not too much. It affects spreading.

PE

 

[kb3lms]

Thank you for your input everyone. Tonight's meeting was canceled so I had a chance to play. A small quantity, about 20 ml, of the emulsion was digested for 90 minutes at 55C with no fog as evaluated by using the blotter test, see above. No sensitizer (e.g. Stiegman's) was used until I got to 70 minutes when I added two drops to see what would happen, which was nothing of note.

I fact, I was beginning to think my emulsion might be completely insensitive, so I coated a little on a glass slide which I took out into the light and then developed in D-76. It fogged just like it should.

After 90 minutes I coated the remaining emulsion on some glass slides to hopefully expose in camera tomorrow.

So I am willing to write the 40 minute limit down to poor washing procedure. Again, thanks everyone!

-- Jason

 

[kb3lms]

Conductivity is measured with any pH meter set to the proper setting. OTOH, if you have a normal VOM from Radio Shack for example, just set it up with the electrodes and select resistance. Conductivity is the reciprocal of resistance. I use vAg or pAg and can give details on this, but it is complex and requires special electrodes.

Re-reading some of the articles I have squirreled away, I found some more information on conductivity in the article "Labratory-Scale Photographic Emulsion Technique" by Thomas T. Hill.*

In the section on Neutral Bromide Emulsion Formula is found this: "continue washing until conductivity of water drained from the noodles reaches a value of 1800 x 10^-6 mho/cm." Guess what? The P30 recipe image shows the very same number for conductivity at the bottom of the first page.

As PE, says above, conductivity, measured in mho (now called Siemens) is the reciprocal of resistance, or ohms, and in this case mho per centimeter. So, then the reciprocal of mho is ohms and 1/1800x10^-6 = 555.6 ohms.

It should be possible then to measure wash water conductivity by placing ohmmeter probes 1 cm apart in the water and looking for a resistace of ~555 ohms to determine completeness. Next time I will try this.

The next question, is 1800*10^-6 some sort of magic number since it shows up at least twice?

* posted on "The Light Farm", http://www.thelightfarm.com The article is well worth your time. Thank you to Denise Ross for taking the time to hunt down this article and post it.

 

[Photo Engineer]

Since these emulsions are both essentially neutral bromide emulsions, the final conductivity should be the same or close to it. It actually represents a maximum vAg to prevent fog if you look at it from another perspective.

PE

 

[Hexavalent]

It should be possible then to measure wash water conductivity by placing ohmmeter probes 1 cm apart in the water and looking for a resistace of ~555 ohms to determine completeness. Next time I will try this.

Do note that conductivity varies with temperature. A measurement of conductivity also reflects all types of ions, not just bromide - having some Mg sulphate in the mix could throw the numbers off.

I've being using salted (bromide) water for the final wash to avoid over-washing (can't remember the concentration offhand). IIRC, there is a table in PE's book correlating vAg and bromide in solution.

 

[wildbillbugman]

What dose pasta have to do with emulsion making?