Spectral sensitizing dyes

Athiril · Jun 16, 2011

Photo Engineer said:
How do you separate the dyes? There are many there!

PE

They wont be effective mixed?

Photo Engineer · Jun 16, 2011

Kirk Keyes said:
The rinse water could be extracted with organic solvent using a separatory funnel. Look up the EPA liquid-liquid extraction. Still sounds like a lot of work...

Kirk;

Sensitizing dyes used currently are highly ionic!

Dan;

The mix is ok, but if you want red only, you have a problem just as an example. And, the dye mix would include acutance dyes and trimmer dyes among others.

PE

Kirk Keyes · Jun 17, 2011

Salt the dye out and adjust the pH when you do the extraction. That always helps push ionic compounds out of water and into solvent!

Then use a HPLC (High Pressure Liquid Chromatograph) machine to separate the compounds.

Only about $10,000 in equipment if you make it youself or buy a used one!

It could be done, if one really wanted too... but I bet you could buy the dyes cheaper by the time one teaches themself how to do it.

Mustafa Umut Sarac · Jun 17, 2011

If you search in open course ware of MIT , there are many videos on these separation processes. Each of of them told very detailed and available at Youtube also.

holmburgers · Oct 21, 2011

Ok, update to an old(ish) thread.

This dye, Erythrosine B (CAS: 54530) or Acid Red 51, is available here on eBay for chump change. This dye is in the Kodak list above.

I'm really interested in finding cheap sensitizing dyes for spectral sensitizing, and not necessarily because I am going to try to make a color-sensitive film tomorrow, but to put the possibilities forth so that anyone making emulsions might be inclined to experiment with this stuff down the road.

Sure they might not be the best or most efficient, but they will work, no?

Also, to make panchromatic dichromated gelatin for holograms they use methylene blue as a red sensitizer and Rhodamine G6 for blue/green. Do these dyes have any effect on silver-halides?

Photo Engineer · Oct 21, 2011

Rhodamine may or may not work. IDK. The structure looks marginal.

PE

holmburgers · Oct 21, 2011

Could you elaborate a bit on that Ron? It's kind of cryptic...

How do you spell the guy's name whose responsible for J-aggregation, Jelly?

Photo Engineer · Oct 21, 2011

Chris;

With few exception (Erythrosine and Chlorophyll being two I can name OTOMH), emulsion sensitizing dyes have positively charged Nitrogen atoms in them.

See attached. There is a resonance plus charge carried by one of the Nitrogens as the electrons resonate. Compare with Rhodamine.

PE

wildbillbugman · Oct 22, 2011

Good morning Ron,
While this subject is being discussed, I am running low on my stash of Sands 3057 . I hope that it is still availible to individuals. But if not, you mentioned another green and a red sensitizing dye you were getting for your own panchromatic work. Are they obtainible by individuals like me? Are they similar in price to the Sands Dyes.
I would hate to have to go back to grinding spinach and little red beetles!
BTW: Way back on the First day of your Workshop a t the Formulary, you warned me of the difficulty I would face in making a panchro emulsion. You were absolutely correct! Here it is, how many years later, and I am still working on it! But, If I had to do a color separation project today, I could do it with my current emulsion. It is just not as fast as I would like it to be. Filter factor for the blue separation filter is X22! That, coupled with the fact that I have stubournly refused to use gelatin, has made this a long project! Its a very good thing, for me, that I would rather do research than make art!
Bill

Photo Engineer · Oct 22, 2011

Bill;

Red and Green dyes are available through Sands. The price is about $100 / gram or more.

Blue sensitizers can be had from Honeywell in Germany for about the same price.

AFAIK, neither list them on their web sites, but you can e-mail them or call and they will give you product numbers.

But, don't use a blue filter. Since a plain raw emulsion is blue sensitive, no filter will give you much higher speed.

Best of luck.

PE

wildbillbugman · Oct 22, 2011

Photo Engineer said:
Bill;

But, don't use a blue filter. Since a plain raw emulsion is blue sensitive, no filter will give you much higher speed.

Best of luck.

PE

That is assuming that I am using 3 emulsions. 1 each with no spectral dye;a green sensitive dye;and a red sensitive dye. That is a possibility. But if I use a single Pan emulsion, I nead 3 negs. one each made with red; green and blue filters. No filter will give me a full spectrum negative.
B

Photo Engineer · Oct 22, 2011

Blue sensitizing dyes do not impart much speed to an emulsion. They just give an intense band at one end or the other of the blue region. If you have such low blue speed, you may be adding too much green or red dyes. After all, sensitizing dyes are desensitizers as well, if used in too high quantity.

That is why most companies use one broad dye for pan sensitization. You might inquire about that at Sands.

PE

wildbillbugman · Oct 22, 2011

Thank you PE,
I knew of pan sensitizers. I think that you have mentioned them on your Forum here. But I believe that you also indicated that they tend to be secrets of individual Companies ( like Kodak).
But I will enquire about this with Sands.
Early on, I cut my leval of 3057 from your recommended 200mg/ per mole of Ag to 150mg. Then I got the cyan colored emulsion instead of a red color.. But this is highly dependent on Ag/halide grain size. And my grain size is smaller than it used to be. But I do get the bright cyan color that I am supposed to get. My leval of 3008 green sensitizing dye has remained at 100mg/mole of Ag. And I have not tried to reduce it yet
I can live with the speed that I am getting now, as I can get a full gray scale at 1 second at f45. But I want more speed because my preffered subject matter requires bellows extention as well as small apature for macro photography.
Good weekend,
Bill

Photo Engineer · Oct 22, 2011

Even with Sands, these dyes are considered proprietary in some cases, and they will not tell you the structure. They will only supply a suggested solvent and a curve of the spectrum.

In any case, don't take ANY dyes containing Selenium. They are too toxic for home use and need industrial quality equipment for safe handling. Sands sent me one for a test, and it remains in their safe packing material in a refrigerator dedicated to chemicals. Paul Gilman saw the dye, knew what it was and told me to never use it due to its toxicity.

PE

Kirk Keyes · Oct 24, 2011

PE - Could you list some pan dyes - from Sands or otherwise?

Bill - I think it's been 4 years since that fatefull first day of class.

Photo Engineer · Oct 24, 2011

Kirk;

I have no panchromatitc dyes. Sorry. I have blue green and red.

PE

wildbillbugman · Oct 24, 2011

Kirk- Heck! we both coulda gone through 4 years of Accounting School and become CPAs by now ! But how much fun and challenge would that have been?
Bill

holmburgers · Oct 25, 2011

Photo Engineer said:
Chris;

With few exception (Erythrosine and Chlorophyll being two I can name OTOMH), emulsion sensitizing dyes have positively charged Nitrogen atoms in them.

See attached. There is a resonance plus charge carried by one of the Nitrogens as the electrons resonate. Compare with Rhodamine.

PE

Ok Ron, here is rhodamine 6G and B's structure. And I included the one you posted, which is....? Are those just "cyanines"?

This is a completely foreign language to me, but I'd like to learn it. What do you call these kinds of diagrams?

Photo Engineer · Oct 25, 2011

Chris;

These are structural diagrams of organic chemicals. The first two have charged amines in side chains, and the "real" SS dyes have the charged nitrogen in a ring structure called a heterocycle. There is a huge difference between the two types of structure regarding the distribution of charge (electrons) and in the latter case it allows the dye to bind to the surface of the silver halide crystal and to transfer energy from light to the crystal.

The former two may or may not, but even if they do, it would probably be inefficient. Erythrosine is more similar to the former two in a way, and it is quite inefficient in energy transfer and so it is more difficult to use in some cases.

PE

holmburgers · Oct 25, 2011

Here's Erythrosine just for reference.

Ok, so if these non-ideal S.S.D. (spectral sensitizing dyes) aren't as efficient, how exactly would that manifest itself? For starters, let's pretend we have an experimental silver emulsion that is completely unsensitized and it has a speed of 100.

The 100 would apply to blue. Presumably green would be much lower (by a factor of what?) and red lower yet.

So if we remake the exact emulsion but add dye X as a "final" (is that when you add SSDs?), how would that effect our distribution of speeds in the blue, green and red portions?

I'd like to roughly understand the practical differences between SSDs like erythrosine, congo red, etcetera (old-school sensitizers) and the ideal cyanine dyes.

I realize this is a dense (in more ways than one!) post.

Photo Engineer · Oct 25, 2011

There are many results possible Chris.

You may end up with no speed at all, matched green and blue speeds or reduced blue speed and some green speed. This includes all variations in between. The answer is "it depends"!

Sorry, too many imponderables. And even if it works, how will you measure it? There are ways, but it takes either equipment or special step wedges.

PE

holmburgers · Oct 25, 2011

If I pay you $10 will you just tell me what I want to hear?

Ok, so if you add too much SSD, it becomes a desensitizer right?

As for measuring, didn't they use prisms basically to spread out the light? How do they make those wedge spectrograms? It seems simple in theory, but maybe it's harder than it sounds to get an even distribution of spectral colors and with a gradual fall-off.

Photo Engineer · Oct 25, 2011

Yes, most SSDs are sensitizers and desensitizers depending on concentration. That is why I have been doing all the hard work for you guys getting it right!

At $100 / gram, you can go broke fast.

And, a monochromator is what you need and what you have described in your post Chris. It is a prism or diffraction grating that splits white light into a rainbow.

PE

Hexavalent · Oct 25, 2011

What about "Mowrey's Fantastic Panchromatic Sensitize-All" - just add two drops per mole Ag.

There's a winter project for you Ron

wildbillbugman · Oct 25, 2011

That is why I have been doing all the hard work for you guys getting it right!

At $100 / gram, you can go broke fast.

PE[/QUOTE]

PE,
I guess that I have been just pounding my Pud all this time!? Try $150/gram. That is what I paid + a "Convenience Fee". I have requested a new quote. But I am sure that the price has not gone down.

Spectral sensitizing dyes

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