The definitive word (I hope) on color stabilzers!

[cinejerk]

formalin source

Took me a while to find a source for formalin. Searching through ebay proved fruitless !!

I'm not affiliated with this guy just found his prices reasonable.

Talk to Tom at: lsalow@peakpeak.com

 

[zehner21]

So, is the formalin based stabiliser suitable for ra4 print?

 

[Photo Engineer]

You don't need one for an RA4 print but EK does make a stabilizer for prints. And, the formalin stabilizer has no bad effect on an RA4 print except that you have to get the excess wiped off before it dries.

PE

 

[fdonadio]

What does this mean? ALL C41 films made before about 2000 and all E6 films need formalin in sole form or another. Leave it out and your negatives and slides will turn green or red and may show a brown stain. If your process for these films does not contain formalin you will have problems in months, days or years. I cannot predict the failure rate. E6 processes without formalin or a pre-bleach bath will cause eventual problems whatever the date the films were made.

Current color negative films (like Portra and Ektar) could benefit from a final rinse containing formalin? Or can I just omit it?


Cheers,
Flavio

 

[Photo Engineer]

A final rinse of some sort is recommended for ultimate stability. The type of stabilizer or final rinse depends on the type and age of the film.

PE

 

[fdonadio]

A final rinse of some sort is recommended for ultimate stability. The type of stabilizer or final rinse depends on the type and age of the film.

Great, but I meant current films, as in film available in stores now, manufactured way after 2000! And, of course, I talk about negative film, as it's pretty clear that E-6 needs formalin.

I've found some MSDS sheets from a Brazilian manufacturer of development chemicals. Their "stab" contains diethyleneglycol, "anionic surfactant" and "isotiazolone derivative".

Their developer formula looks pretty much the same as the ones in the patents.

It's in Portuguese, but one can easily figure out what the chemicals are... Just click on the links "Ficha de Segurança" to see the MSDS information:

http://www.afq.com.br/afq41r.html

Google translations are usually terrible, so I didn't even try them.


Cheers,
Flavio

 

[LarsAC]

If I understand correctly, stabilizers of current C-41 kits (Fuji Hunt, Rollei, etc.). do probably not contain Formaldehyd ?

Lars

 

[Photo Engineer]

Current C41 stabilizers do not contain Formalin.

PE

 

[Rudeofus]

As described in great detail by PE, C-41 film, old or new, needs some compound which kills bacteria and fungus. This "isotiazolone derivative" is probably some compound derived from Isothiazolinone, which is such a biocide.

As it just so happens, Formalin is a biocide as well. There is published research that Formalin is not the best biocide to use, but it is one of the very few that are available to us amateurs as raw compound. Unless someone can point me to a readily available and not overly hazardous compound (Chloramine-T?) to use as biocide in a self mixed final rinse, home brewers are pretty much stuck with Formalin, even for C-41 and modern film.

 

[Photo Engineer]

Well, Formalin served 2 purposes in C22 films. One was a biocide and the other was to react with unused coupler. The dyes would fade without formalin and the bugs would eat the gelatin.

In today's films bugs eat the gelatin, but the dye fade problem has been solved without formalin.

PE

 

[LarsAC]

Current C41 stabilizers do not contain Formalin.

PE

Thanks, good to know. Having read about Formaldehyd / Formalin I was tempted not to use the final stabilizer bath. My concerns seem without reason, then.

Lars

 

[Rudeofus]

In today's films bugs eat the gelatin, but the dye fade problem has been solved without formalin.

The problem with biocides is that in their pure form they are very toxic to us humans, too. Since they are used in trace amounts (0.02 g/l 1,2-Benzisothiazol-3(2H)-one in Fuji's E6 STAB), they are needed in such small volumes that chemical retailers won't put up with the risks and dangers that come with selling such compounds to us.

The reason why I asked about Chloramine-T was because you can get this compound from Suvatlar, and it's the only biocide that I see available to photo amateurs. AFAIK there is nothing suitable listed on Formulary's page.

Can you post a working C-41 STAB recipe based on Photoflo, Chloramine-T (or something available from Formulary) and distilled water?

 

[Photo Engineer]

Chloramine-T is not suitable as a biocide in film. It decomposes rapidly in humid conditions to give Chlorine which destroys both dyes and gelatin.

Sodium Benzoate is a good biocide but rather weak. I suggest it be tried.

PE

 

[Rudeofus]

Chloramine-T is not suitable as a biocide in film. It decomposes rapidly in humid conditions to give Chlorine which destroys both dyes and gelatin.

Thanks for the heads up, good to know.

Sodium Benzoate is a good biocide but rather weak. I suggest it be tried.

Would benzoates work in dry state? This text claims it works only in acidic environment, whereas color film should end up with pH 6.5 IIRC.

BTW Tetenal's STAB uses this 1,2-benzisothiazolin-3-one compound, just like Fuji's. So does Kodak's ECN-2 final rinse. I'm beginning to wonder whether there are any reasonable alternatives to this compound ...

 

[fdonadio]

As described in great detail by PE, C-41 film, old or new, needs some compound which kills bacteria and fungus.

Yeah, I've read his post (following your suggestion on another thread) thrice and, although very detailed, I didn't find his post clear enough, hence I asked if there was any benefit. He was too focused (IMO) on the coupler issue, not on the "bug" issue.

Later posts finally answered my question: new films don't need formalin to stabilize the couplers, but still need it to be protected from micro-organisms.

Don't get me wrong: I don't think anyone has the obligation to answer just because he/she participates in this forum. Time is a valuable asset to everyone.

Thanks everyone for the help. I am going to use formalin, as the other "options" are way more toxic (isothiazolinone) or not proven (benzoate).

Suggestion: here in Brazil, you can find formalin (10%) in drug stores. Maybe it's the same abroad...


Cheers,
Flavio

 

[Photo Engineer]

I said Benzoate was weak, and it does work up to about pH 7, so I see no problem. It does crystallize out at high concentrations so one must be careful.

In all color films up to about 2000, dye fade on keeping was a primary problem (and still is for E6 films). So the effect of a stabilzer on bugs was a secondary, but real, concern. This problem was pretty much fixed in the '60s for color papers, but a stabilizer for them still exists as well for the RA process. It too is for bugs.

So, now stabilizers are needed for bugs because the color negatives and prints can last so long. No R&D is being done on E6 products to improve that situation.

PE

 

[chazum0]

I had been wondering about this. I use the unicolor c41 powder kit and on the stabilizer package the contents state that it only contains "Hexamine". I did a simple Google search to try to find more information on it, but I'm no chemist. Also, is it possible for me to mix a bit of photoflo 200 with my stabilizer like you suggested for those using the formalin mixture?

 

[Rudeofus]

chazum0: IIRC Hexamine hydrolyzes into Formalin, Ammonia and some other compounds, so FWIW you can see it as a source of Formalin.

 

[Roger Cole]

Formalin is pretty available so why the push for something else? Modern C41 may not need it for dye stability but if one wants to scratch brew a stabilizer for microbe control will it do any harm to just use formalin for C41 just like E6?


Sent from my iPhone using Tapatalk and 100% recycled electrons - because I care.

 

[Photo Engineer]

All Stabilizers and Final Rinses should contain a Photo Flo like component along with either Formalin or some other bacteriostat or dye stabilizing agent depending on which film you are using. This was all explained in the OP.

PE

 

[Rudeofus]

Roger, Formalin is a volatile compound which may not stay in film during prolonged storage. I would expect this to be even more of an issue in hot, moist climate, which is exactly the climate where microbes dwell. I would see it as a great warning sign, that Tetenal, who use the same STAB for C-41 and E6, and who's STAB contains a Hexamine, also put the benzoisothiazolinone compound into their STAB. This tells me that Formalin alone won't do. This issue is also described in "Fungicidal Rinses for Color Processed Film" by Mackey and Johnson (Photographic Science and Engineering, volume 3, number 3, page 132ff).

Interesting side note: this paper mentions Thiourea as very potent fungicide, and rejects this compound only because leakage from STAB back into color developer can cause problems. I think this would be a complete non issue for most amateurs. Can anyone tell me how much Thiourea I would need in final rinse to make it work?

 

[Photo Engineer]

Formalin stays in the film and active almost forever.

It reacts with one amine on gelatin or the active site on residual couplers and forms a biocide barrier with its presence. Thus, there is no reason to worry about formalin "leakage" and loss of activity.

I would not recommend thiourea as a biocide.

PE

 

[Rudeofus]

I just checked the MSDS for Ilfotol, and it seems to contain a strange mixture of 5-Chloro-2-methyl-3(2H)-isothiazolone with 2-methyl-3(2H)-isothiazolone registered with CAS number 55965-84-9. These compounds look a lot like Benzisothiazolinone, and I wonder whether these work as biocides like the latter one. If that is the case, especially after 1+200 dilution of Ilfotol which already contains this compound in less than 1%, can we make a C-41 STAB for modern film with Ilfotol alone?

 

[Photo Engineer]

I have no idea, and the experiments to verify effectiveness without harm would take a lot of work.

I'm sure that Kodak and Fuji selected the optimum compounds for their color films. These compounds were not selected for color dyes.

PE

 

[Photo Engineer]

Imagine organic chemistry in German!

I had to do a lot of translations to English for my study and thesis.

PE