Panchromatic Emulsion

[wildbillbugman]

Ray,
Thanks. Mabe I'm just overly sensative. I am painfuly aware that my carcase cannot keep up with my ambitions.
Let us forget it,
Bill

 

[Ray Rogers]

(Bill, just between you and me, I think Ron was actually talking about me!)

 

[Photo Engineer]

My comments were meant for no one here on this thread at all. Sorry for the misunderstanding. I apologize for any confusion.

As for testing Bill, I suggest using a WR 98, 99 and 70 (or equivalent narrow cutting filter set) over a step chart and exposing. An in-camera exposure is difficult to read, but a 3 color filter set with and without dye will give you the exact speed change in each region affected in terms of Log E (stops) speed change.

I've tried the method you describe, Bill, and it is just not clear cut enough. However, if you wish to send me a sample, I'll expose it with my spectrosensitometer.

PE

 

[wildbillbugman]

Thanks Ron,
I will follow your suggestion concerning exposing through WR filters. Sound a bit easier anyway.
Bill

 

[Kirk Keyes]

Bill - you should take Ron up on the spectrosensitizer. I've seen test prints from it and it is really cool and gives results just like you seen in the graphs in books and such.

 

[Photo Engineer]

Bill;

I forgot to reply to this.

I am trying to make emulsion making as fool proof and "un-arcane" as possible in my formulas. I hope you saw that in the emulsions we made. They are just about dump and stir.

I'm trying to make the advanced emulsions easy as well, but they will cost more in terms of equipment though.

I have not addressed finishing yet, I've merely used a standard condition more or less worked out by trial and error here at home with the bench top emulsions.

I was not pointing a finger at anyone here in this thread, nor intending anything bad about anyones work. Sometimes though I feel like a person who has started a huge rock rolling downhill. I have to step back to get out of the way. Other times, people point at me and say "its all his fault and he doesn't know what he is doing" as the rock goes bounding down hill.

So, that is all there was to my comment. I feel as if I want to be there to help!

Now for finishing, you are using thiocyanate + gold. Here is the order of use timewise from early days to modern:

Active gelatins > Allyl Thiourea > Thiourea > Thiocyanate > Sodium Thiosulfate

Gold was used after about 1945 at Kodak with all of the above, but hypo was used exclusively for Sulfur sensitization since the 50s or 60s. Of course there is Reduction Sensitization (R type) which uses Stannous Chloride and a whole variety of other methods. Hypo seems to be the compound of choice for sulfur + gold though, but the hypo must be freshly mixed.

Hypo and the others above put Silver Sulfide specks on the grain, but Stannous Chloride forms Silver metal specks on the grain.

Other methods include addition of strong alkali, strong acid and a host of other methods to form a speck on the grain to "jump start" latent image formation.

PE

 

[dyetransfer]

Sensitizing Testing with Glass plate

Hi Jim,

You watched then do this?
How long diid it take between coating and judgment?
After this sort of test, what were their possible moves?

Ray

Hi Ray - I did watch them do this. Every 10 minutes or so, they would coat a glass plate with emulsion, expose it with a projection system. and develop (but not fix it). They would bring the plate into the emulsion chemist's office in a box and she would evaluate it quickly after removing the lid in full office light. She whould inspect it for fogging, and color change. Of course, since it wasn't fixed out, she had to work quickly. I'm not sure how long the process took to do, but the important thing was the record of samples 10 minutes apart which were done as the emulsion was sensitizing. Take a look at the attached file.

Regards - Jim Browning

 

[dyetransfer]

Hi Bill - I use glyoxal now as a substitute for formalin in my hardner. I use the same concentration, and it works well. This is the hardner I use on the matrix after it has been washed off. This makes for a much more durable matrix. Not sure how it would work in an emulsion though, that is a much more complex thing.

Regards - Jim

 

[Ray Rogers]

Hi Ray - I'm not sure how long the process took to do....

Regards - Jim Browning

Jim, what size plate are we looking at?

I was wondering about
how long and completely
the emulsion was allowed to set.

Interesting chart- do you have a close up of it, or know where its from?

Ray

 

[Photo Engineer]

The method of using the glass plate that Jim describes above is limited in some cases such as our lab bench scale emulsions. A plate coating for a 4x5 takes about 6 ml of emulsion and over a 60 minute finish will therefore require about 36 ml of emulsion from a 200 ml batch as one example. That is a lot to use before you even start. To add to this, often we are making slow speed emulsions that cannot be easily printed by projection. Some print film and paper emulsions could not be tested this way due to speed and volume being made.

Just some thoughts. It is useful but there is a better way.

PE

 

[Ray Rogers]

A very long Three Dog Night

"...people point at me and say "its all his fault... he doesn't know what he is doing"

I must say that I have seen both sides of the story.
I see a lot of misunderstanding mixed in with a lot of ego conflict / ego injury.

Alas, we are but human!

Thives of another animal's breast milk!

Ray Rogers

 

[dyetransfer]

Hi Ray - the plate size was 4 x 5". Not sure how long it took the gel to set or if the plate was chilled, but I imagine that it was. Obviously, you want to develop the image as soon as possible after coating it so the emulsion doesn't continue to evolve. The chart was a glass plate (I think) that was placed in a very old looking projector - black wrinkle finish. But the projector looked to be very well made and the projected image was sharp. I don't know what they developed the plate in, but I doubt it was pyro.

Regards - Jim

 

[Ray Rogers]

Hi Ray - the plate size was 4 x 5". Regards - Jim

OK,

Thanks Jim.

 

[Kirk Keyes]

The method of using the glass plate that Jim describes above is limited in some cases such as our lab bench scale emulsions. A plate coating for a 4x5 takes about 6 ml of emulsion and over a 60 minute finish will therefore require about 36 ml of emulsion from a 200 ml batch as one example.

Ron - You may have missed it, but Bill said he was going to make 1L of emulsion, so he should have plenty to test with. But for much smaller batched, this method would cut in quite a bit to the final volume.

 

[Kirk Keyes]

The method of using the glass plate ...
Just some thoughts. It is useful but there is a better way.

OK - did I miss the description of the better way? Or have I just forgotten it?

Kirk

 

[Photo Engineer]

I discussed the other method in the workshop Kirk. Maybe that was the day you were late, or the day you fell asleep and fell out of your chair.

Basically, the only parameter that is important in an emulsion while finishing, if the emulsion is any good to start with, is the fog level. So, all you have to do is test one drop of emulsion for fog. When it starts to rise, the finish has gone as far as it can! Voila, c'est fini.

PE

 

[JOSarff]

And I will try a gold chloride sensitizer(Stiegmann's?), after I haved looked at it without one.

Bill:

I asked about the Steigmann sensitizer in a thread called 'Sulfur and Gold sensitation'. Ron was kind enough to supply some guidelines on sulfur and gold content that is closer to a 3:1 ratio, rather than Steigmann's 8:1

To Quote Ron's reply:

The data below assumes the use of KAuCl4 and Na2S2O3.H2O for sensitization:

The data are stated as gold/sulfur in milligrams / mole of silver

1/3 for 1.0 micron grains
5/15 for 0.5 micron grains
35/100 for 0.1 micron grains

The attached chart shows the relationship to the vAg and the crystal habit that is formed. From this, you can see that my crystals in the second attachment are made at a vAg value between 7.5 and 8. The extreme rounding is due to the ammonia used to digest (grow) the crystals, and if taken much further the crystals would be nearly spherical.

PE

He also attached two jpg's with some good info.

Hope this helps.

Joe

 

[wildbillbugman]

Thanks Joe,
Now that you mention it, I do recall that post(s) by Ron.
Kirk,
In my earlier atempts to make emulsions, I had so much trouble with foging that I developed the habit of using Ron's "1 drop" fog test at every step. Now, whenever I make an emulsion, I am constantly sacrificing 1 drop to the Gods of Fog.
Bill

 

[dyetransfer]

I don't think Fotokemika would have done the sensitization test every time they made an emulsion - once you do the test using this procedure, it would have gone too far, and the emulsion would be fogged and unusable. The idea is to continue sensitizing until you detect some fog, and then the NEXT time you make a batch, sensitize for LESS time so that fogging doesn't occur. This should work as long as you use the same materials, batch size, cooling times, etc. Once you have the proper time/temp/concentration for sensitizing, you just stick with it, and shouldn't have to repeat the test.

Regards - Jim

 

[Photo Engineer]

Jim;

You can sensitize to the first appearance of fog and then add an inhibitor or stabilzer. That is rather kludgy, but it works. Since you do both in your formula, the approach you were taking was not clear to me. I would have had to do your experiment to clarify it for myself.

PE

 

[Photo Engineer]

Joe;

Thanks for posting that again. I would like to remind people that sulfur and sulfur + gold react differently and require a different quantity for a given grain size. Also, that chart does not apply to Thiocyanate. I would have to look up specific examples, if I even had any. We did not use thiocyanate in anything I worked on AFAIK.

For the above example that Joe copied here, it was a Br/I emulsion, made at about pAg of 8 on the chart as you can see by the crystal habit. I used 100 mg/mole of Sodium Thiosulfate.5H2O for a sulfur only finish. You can see the difference.

PE

 

[Kirk Keyes]

I discussed the other method in the workshop Kirk. Maybe that was the day you were late, or the day you fell asleep and fell out of your chair.

Basically, the only parameter that is important in an emulsion while finishing, if the emulsion is any good to start with, is the fog level. So, all you have to do is test one drop of emulsion for fog. When it starts to rise, the finish has gone as far as it can! Voila, c'est fini.

PE

OK - I remember that. But maybe it was after I fell out of the chair. And I was not sleeping!

 

[Ray Rogers]

my crystals in the second attachment...
Joe

Ron, It is 4 something here- I just woke up...

Are the crystals in the second jpg ones you actually precippitated for these experiments, or is the photograph just taken from a similar emulsion?

Ray

 

[Photo Engineer]

Kirk;

I know that! You were a very diligent and alert assistant, and you can work with me in the DR anytime. But why did you fall out of the chair?

I know, you didn't fall out of a chair. I was joking.

But for the rest of you, the 1 drop test for fog is what you can use commonly to determine the extent of finish using a sample with all of the sulfur + gold. Then you take 30 ml and heat to 60C and take 1 drop every 10 minutes and test only for fog. Take the remainder of the batch and treat the same way.

PE

 

[Photo Engineer]

Ron, It is 4 something here- I just woke up...

Are the crystals in the second jpg ones you actually precippitated for these experiments, or is the photograph just taken from a similar emulsion?

Ray

That is one of my emulsions Ray.

PE