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CAS Numbers for chemicals used in emulsion making

Nodda Duma

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Searching for chemicals, I’ve realized many of the less common chemicals of interest in emulsion-making — particularly stabilizers, anti-foggants, etc., have many synonyms and are called different names by different industries.

As far as I can tell, the best way to source or find info on a specific chemical is to search by a catalog number such as the CAS number. Some chemicals (like gelatine or silver nitrate) you don’t really need to search by the CAS number, but in some cases — like TAI or PMT (stabilizers / anti-foggant) you’ll have better luck if you do.

For example, water has a CAS number 7732-18-5.

You can find more info on CAS via its wikipedia page. There are other chemical catalogs but this happens to be the one I started using.

Feel free to add CAS numbers for chemicals of interest.

Gelatine: 9000-70-8
Silver Nitrate: 7761-88-8
Potassium Bromide: 7758-02-3
Potassium Iodide: 7681-11-0
Erythrosine: 16423-68-0
PMT: 86-93-1
TAI: 2503-56-2
 
Seems like a good candidate for a "Sticky" thread designation.
 
The CAS for gelatin should vary wrt Bloom number and type (pig, bone etc...) and the erythrosine should vary depending on being a salt or free acid.

ETC...

This has been my problem from day one.

PE
 
Yeah for those the CAS isn’t as helpful as the common names, but I had a heck of a time tracking down TAI until I searched by CAS.
 
Here're some from my chemicals shopping list:

Dyes:
Rose Bengal: 11121-48-5
Pinacyanol chloride: 2768-90-3
Ethyl Violet: 2390-59-2
Tartrazine (Acid Yellow #23): 1934-21-0

Ammonium salts:
Ammonium chloride: 12125-02-9
Ammonium bromide: 12124-97-9
Ammonium iodide: 12027-06-4
Ammonium thiocyanate 1762-95-4

Miscs:
Chrome alum: 10141-00-1
Thymol: 89-83-8
Calgon (Sodium hexametaphosphate): 68915-31-1

Most of them can be acquired without owning a research facility under your name.
 
Great additions to the list!

The direct chemical suppliers for the most part typically have policies against shipping to a residential address, whether or not you are running a business. I did finally find a source, but had to document for them that I needed the chemistry for legitimate (R&D / commercial) reasons and had the facilities (PPE, storage, disposal, etc) & experience to handle hazardous chemicals.

I also reached out to Bostick & Sullivan when I was having trouble finding someone to ship TAI to me. They were more than happy to acquire chemicals and then ship me what I needed. I ended up not needing to source through them, but that's an option in case you need something they don't carry. Photographer's Formulary would do the same, judging by prior posts here in the forum.

Regards,
Jason
 
Dyes

Pinaflavol: 3785-01-1
Pinaverdol: 2578-40-7
 
Last edited:
Chrome Alum seems to be a little confusing, if you start looking around to source exactly what you need.

From what I've been able to tell, CAS 10141-00-1 is the CAS # for chromium potassium bis(sulphate) aka Cr.2H2-O4-S.K aka (KCr(SO4)2). The chemical suppliers that I looked through leads me to believe that this CAS is specifically associated with the chemical supplied in aqueous solution (~0.5 M)... at least as far as I can tell.


Chromium(III) potassium sulfate dodecahydrate a.k.a. CrK(SO4)2 - 12H2O with CAS 7788-99-0 is the powdered/crystalline version that you would most commonly encounter.

The data and CAS for chromium potassium bis(sulphate) is what's listed in Wikipedia, although the images appear to be the dodecahydrate form. I'm going to edit the Wikipedia page to add the dodecahydrate CAS

That said, it doesn't seem like either Photographer's Formulary or B&S list chrome alum for sale any longer. I'm sure they would get it for you if you asked, and you can find it on ebay or chemical supply houses as well (all listed when I checked were CAS 7788-99-0)... of course, the caveats about the quality of ebay chemicals applies.

Cheers,
Jason
 
Apologize for the confusion and I agree with Jason re: Chrome Alum. I don't have the bottle of Chrome Alum that I got from silverprint.uk with me anymore, but on wetplatesupplies the Chrome Alum listed is indeed the 12H2O. I believe Silverprint will give you the same thing.

Thus the 'correct' CAS for it is 7788-99-0 .
 
Gold (I) Chloride for Steigmann's Solution: 10294-29-8
 
Nodda Duma said:
Yeah for those the CAS isn’t as helpful as the common names, but I had a heck of a time tracking down TAI until I searched by CAS.
Click to expand...
What about the difference of CAS numbers Nodda Duma? I notice years ago ! From day No.1 I had the concern of 1) translation of names for chemicals (beware of ! btw), 2) from day No. 4 I was involved with CAS numbers and had the need of Wikipedia to compare chemical structure!

Day No. 5 I can't find supplier for CAS No. 7757-83-07 (pls. add it to your list boys) I had the need to order for my D-23 (without the knowlage to ask for in grocery)!

So at last there is no CAS No. to different chemicals but (if I remind correct) there are some chemicals with more than one CAS No. What about the nomentaclure of CAS there?

with regards
 
trendland said:
Day No. 5 I can't find supplier for CAS No. 7757-83-07 (pls. add it to your list boys) I had the need to order for my D-23 (without the knowlage to ask for in grocery)!
Click to expand...
7757-83-07 is not a valid CAS number. The last group only has 1 digit.
 
minh0204 said:
7757-83-07 is not a valid CAS number. The last group only has 1 digit.
Click to expand...
Sorry folks [I had a hart working day yesterday about 15 hours...] possible a much too short night
to sleep and/or a bad remind....!
7757-83-7 has an other concern (D23)!

What I realy wanted to advice you is CAS No. 7647-14-5! (Microdol-x derivate formulation)!
I was searching for a chemical supplier in the early days - but wasn't able to find!
So I had the imagination it is a restricted chemical - impossible to order from reasons of
regulatioons!! So no microdol x homebrew....?

Boys this is a cristal chemical from cubic structure with a mol mass of 58,44g•mol-¹ the specialty
is its melting point at 801degreeC!! It's ATC Code is A12Ca01 = your doctor is allowed to order
it ! It is also avaible in emergency case = Hospital! How to come to that stuff and not to come into trouble with the sheriff's department?

(7647-14-5 is Nacl).......

with regards
 
Hmm - that was the tablet : NaCl !!!!
 
Sodium Chloride: 7647-15-5
Sodium Bromide: 7647-15-6


Just a reminder that the CAS numbers in this thread are for emulsion-making chemicals. I’d like to keep tightly focused on that subject to avoid diluting the information. This very specific information is compiled nowhere else in the world's public domain that I can find and is therefore unique.

If you’d like to discuss chemicals for developing, I’d like to request that you start a discussion in the B&W: Film, Paper, Chemistry sub-forum.

Thanks,
Jason
 
Sorry much Jason - I overlooked the topic (emulsion backing CAS...) much much :
Mea Culpa!

with regards
 
Couple more dyes:

Quinaldine Red: 117-92-0
Pinacyanol Bromide: 2670-67-9
Pinacyanol Iodide: 605-91-4
Cryptocyanine/Kryptocyanine (Iodine): 4727-50-8

All of those dyes could be sourced through wetplatesupplies for the time being.

Also a side note, could PE or someone comment on the difference between the different flavors of pinacyanol?
 
The two dyes exist as salts:

https://www.sigmaaldrich.com/catalo...MIvNr6z8qq4gIV1_ZRCh3_sgYEEAAYASAAEgJmxfD_BwE

Replace Bromide ion here with Iodide and you change one to the other.

Use in photographic emulsions depends on effect. The Iodide will add to the emulsion and release Bromide thus changing the effective Iodide content of the emulsion by a tiny amount. This is probably insignificant in Bromide or Bromo Iodide emulsions, but will have a big impact on Chloride emulsions and some even on Chloro Bromide emulsions.

That is about it.

PE
 
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