Where do the current big film manufacturers source their spectral sensitizers from?

Hi there,

I've been playing around with the idea of making my own film emulsions for some time now; having made some basic emulsions before and having read way too many book about organic chemistry, I was wondering, where do companies like Kodak, Ilford and Foma source their spectral sensitizers from? Does Kodak still synthesise them in-house?

It seems to me that the biggest secrets in silver halide manufacturing really does come down to the spectral sensitizers.

I'm looking to make a basic panchromatic film; any pointers on where I can get these sensitizers?

Cheers!

You find or found these substances at the catalogs of the chemical industry. But unless used by other industries these are not a off the shelf products. But you may try other dyes, off the shelf available, made for other uses. Of course you may also approach one of the other manufacturers, labs that custom synthezise for you organic substances even in gramms amount.

But... have you so far made unsensitized film?

haliderollei said:

It seems to me that the biggest secrets in silver halide manufacturing really does come down to the spectral sensitizers.

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PE commented that they were indeed, and not easy at all to get because of this secrecy (you can't order something you don't know what it is). Also because they seem to be very "exotic" compounds.

Former Kodak chemical division is an independent business since 1994, it is called Eastman Chemicals. I don't think Kodak produces any raw chemical component internally nowadays.

AgX said:

You find or found these substances at the catalogs of the chemical industry. But unless used by other industries these are not a off the shelf products. But you may try other dyes, off the shelf available, made for other uses. Of course you may also approach one of the other manufacturers, labs that custom synthezise for you organic substances even in gramms amount.

But... have you so far made unsensitized film?

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Yes I have; basic blue sensitive emulsions

https://nvlpubs.nist.gov/nistpubs/ScientificPapers/nbsscientificpaper422vol17p353_A2b.pdf

https://www.sigmaaldrich.com/CA/en/product/sial/69710

https://www.sigmaaldrich.com/CA/en/product/aldrich/201715

https://www.sigmaaldrich.com/CA/en/product/sigma/j1875

haliderollei said:

Yes I have; basic blue sensitive emulsions

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What types? Have you performed other chemical finishing/ sensitising steps on them?

There are various interactions between emulsion makeup and sensitising dyes (J-Aggregate, for example) - and there can be others within the finishing steps depending on what's used.

H.W. Sands is who Ron Mowrey suggested getting certain specific sensitisers from in his emulsion making book. Whilst Kodak does have onsite SynChem facilities for specific components that aren't available commercially/ immediately, I think most sensitising dyes, or at least the near-to-final components needed to synthesise them in manufacture, are largely bought in from candidate lists that have been drawn up from the catalogues of the specialist suppliers serving the Fine Chemicals market. Sensitising dyes can be extraordinarily expensive, and have short shelf lives (hence the problems of IR film availability) - along with various other potential risks.

maltfalc said:

https://nvlpubs.nist.gov/nistpubs/ScientificPapers/nbsscientificpaper422vol17p353_A2b.pdf

https://www.sigmaaldrich.com/CA/en/product/sial/69710

https://www.sigmaaldrich.com/CA/en/product/aldrich/201715

https://www.sigmaaldrich.com/CA/en/product/sigma/j1875

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Cyanines and Merocyanines are a better place to look for more modern panchromatic sensitising - Frances Hamer's work on them was fundamental.

Lachlan Young said:

Cyanines and Merocyanines are a better place to look for more modern panchromatic sensitising - Frances Hamer's work on them was fundamental.

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Why is that the case? Would love to learn more. Just read the wiki, what a wonderful women.

Fisher Scientific, Spectrum, and Sigma Aldrich all sell pinacyanol chloride. Artcraft Chemicals sells erythrosine. With these two chemicals you can make excellent panchromatic film.

dwross2 said:

Fisher Scientific, Spectrum, and Sigma Aldrich all sell pinacyanol chloride. Artcraft Chemicals sells erythrosine. With these two chemicals you can make excellent panchromatic film.

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Thank you! There is so much to learn haha

You'll be fine. You've already made a colorblind emulsion. The trick is building on that a step at a time. When you're comfortable with colorblind, try ortho (erythrosine). After that, PinaCl. Between them, you've got most of the visible spectrum covered. You're going to have a lot of fun.

haliderollei said:

Why is that the case? Would love to learn more. Just read the wiki, what a wonderful women.

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They (and others like carbocyanines, pthalocyanines etc - Hamer at Kodak Ltd and Brooker at Eastman Kodak set in motion a lot of the basic research into sensitising dyes) offered better & more efficient sensitisation with a wider array of emulsion types - and effects like J-Aggregation allowed for green sensitisers to deliver broader sensitivity into red.

Nevertheless, Denise's advice is the sensible place to start from - and you might be surprised at how much even fairly simple orthochromatic sensitisation makes scenes render more 'normally' to the eye. Also think very carefully about the procedures and equipment you will need in order to instigate making & coating panchromatic materials safely - it's different from working with colour paper or loading/ processing film.

I too have been heading down the panchromatic emulsion rabbit hole, and am only 1 step further along than the OP, having developed a reliable recipe for a slow ortho emulsion with erythrosine (thanks primarily to you, @dwross2!). Pinacyanol is next, though Sigma Aldrich has been out of stock of small quantities whenever I've checked. Will try Fisher and Spectrum next.

What I'm ultimately aiming for is IR sensitivity, which from some older posts here it seems neocyanine may be the best bet? Still haven't found a source for that one...

Well, it took Vogel already about 10 years to come about with something commercially viable.

The real success though was achieved by his successors with custom synthezised dyes.

ProfessorC1983 said:

What I'm ultimately aiming for is IR sensitivity, which from some older posts here it seems neocyanine may be the best bet? Still haven't found a source for that one...

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https://www.sigmaaldrich.com/CA/en/product/aldrich/d91535

ProfessorC1983 said:

I too have been heading down the panchromatic emulsion rabbit hole, and am only 1 step further along than the OP, having developed a reliable recipe for a slow ortho emulsion with erythrosine (thanks primarily to you, @dwross2!). Pinacyanol is next, though Sigma Aldrich has been out of stock of small quantities whenever I've checked. Will try Fisher and Spectrum next.

What I'm ultimately aiming for is IR sensitivity, which from some older posts here it seems neocyanine may be the best bet? Still haven't found a source for that one...

Click to expand...

That's great to hear! Good luck and fun!