Sodium sulfite, hard to get

Rudeofus · Jan 18, 2018

elerion said:
Well, I don't know. But, according to safety data on disactis, it seems that borax is more hazardous.

It appears that MSDS vary a lot between suppliers, and their level of hysteria also seems to depend on their age, i.e. when they were published. Fisher's MSDS appears to be the most honest one: "The toxicological properties of this material have not been fully investigated." Little wonder, this compound has not that many applications outside of photography.

Sigma Aldrich's MSDS gives it the same danger level as Borax, and it makes sense: once it hits your stomach, pH is low enough that all are essentially converted to the same compound Boric Acid and Sodium Chloride. Since Sodium Metaborate is quite a bit more alkaline than Borax, I'd be at least as careful with the former.

elerion · Jan 18, 2018

mmm.... strange.
I consulted several msds, and most (if not all) of them give a health rating of 1 to metaborate, and 2 to borax (tetraborate).
Also, sodium metabisulfite is 2, and sodium sulfite is 1.

True that making your own sodium sulfite is good in the sense that sulfite powder can be degraded into sodium sulfate and loose effectiveness (afaik).

By the way, I'm looking towards phenidone/ascorbic homemade developer because I want to use safer chemicals and as few as possible.

Rudeofus · Jan 18, 2018

elerion said:
Also, sodium metabisulfite is 2, and sodium sulfite is 1.

If you ever smell moist Sodium Metabisulfite, you will understand immediately why Sodium Metabisulfite is more hazardous ... but this is not an issue with Sodium Metaborate vs. Borax.

DavidJRobertson · Jan 18, 2018

Rudeofus said:
If you ever smell moist Sodium Metabisulfite, you will understand immediately why Sodium Metabisulfite is more hazardous ... but this is not an issue with Sodium Metaborate vs. Borax.

Yep, it releases sulphur dioxide gas which is pretty noxious.

elerion · Jan 19, 2018

Cool!

By the way, maybe a stupid question, but couldn't metaborate be substituted by sodium carbonate, until you get the same pH?
I see some recipes using borax, metaborate, sodium carbonate,... they all must be alkali, but I think borax is also used for grain reduction.

lantau · Jan 19, 2018

If you like XTOL but not the 5L size, then see if you can buy Fomadon Excel. It comes in 1L size and should sell below €4.

lantau · Jan 19, 2018

Forgot to mention: Fomadon Excel is an XTOL clone.

elerion · Jan 19, 2018

I know. In fact, I've got one Fomadon Excel unopened pack. It just is much more expensive.
The idea behind making my own developer is experimentation too, and to have some degree of freedom.

lantau · Jan 19, 2018

elerion said:
I know. In fact, I've got one Fomadon Excel unopened pack. It just is much more expensive.
The idea behind making my own developer is experimentation too, and to have some degree of freedom.

I understand. Petty much what I'm planning. I will routinely use commercial developers, but play with some recipes out there.

Also I will need some low contrast developer for experiment with high contrast ortho film and that is cheaper to mix myself.

Rudeofus · Jan 22, 2018

lantau said:
Also I will need some low contrast developer for experiment with high contrast ortho film and that is cheaper to mix myself.

Check out this series of low contrast speed preserving developers, if you have a decent source for Phenidone these are about as cheap as it gets ...

lantau · Jan 22, 2018

Rudeofus said:
Check out this series of low contrast speed preserving developers, if you have a decent source for Phenidone these are about as cheap as it gets ...

Thanks for the link. I'll work my way through that thread. So far I have been planning to use Dave Soemarkos LC-1 developer. I have Rollei ATO2.1 sheet film and wanted to see if I can make slides from medium format negatives and the other way around. A first try using rodinal in a tray wasn't even that terrible. It's not that I want to routinely go this way, but it might come in handy sometimes. Especially to print slides.

Anyway, it seems that all the ortho films left are high contrast. I like the idea of having film that can be handled in the darkroom under safe light. But a low contrast developer will be necessary.

Rudeofus · Jan 23, 2018

Michael R.'s developers are likely superior to most low contrast developers out there, because most low contrast developers follow one of two principles:

exhaustion, see highly dilute recipes Film Developing Cookbook, leading to high shadow and very low highlight contrast
underdevelopment, see POTA, D-25 and most likely this LC-1 formula, leading to speed loss and very low shadow contrast

Contrary to these formulas, Michael R.'s set of formulas create a very straight curve, which means full speed and constant contrast over a very long exposure range.

PS: If you want to make slides, you need a very high contrast developer as FD, not a low contrast one, or you lose tons of film speed. This is not because low contrast developers lose speed by themselves, but because medium tones in your slide correspond to very dense areas after first development. You get these either with very high contrast development, or with extreme overexposure!

elerion · Jan 24, 2018

Rudeofus said:
Check out this series of low contrast speed preserving developers, if you have a decent source for Phenidone these are about as cheap as it gets ...

I'm still reading this thread. It's quite a lot of readng. I just finished post #58, where you post the result of pH for several dissolved chemicals.

I might have missed this, but, why do you say: "Remember we can't use PG if we have Borates in the mix."?

Rudeofus · Jan 24, 2018

elerion said:
I might have missed this, but, why do you say: "Remember we can't use PG if we have Borates in the mix."?

PG and Borate ion form an ester, and this reduces the effect of Borate ion.

elerion · Jan 25, 2018

After some research, these are some thoughts.
I already have ascorbic acid and sodium carbonate, for making Caffenol developers.
I asked myself, could I replace metaborate by carbonate, for making an XTOL like developer (like Instant MYTOL)?

-------
From "Developing The Negative Technique",
by Kurt I. Jacobson, Ralph Eric Jacobson

"[Metaborate] is more alkaline than borax and somewhat more easily soluble, but less alkaline than [sodium] carbonate. When used as a substitute for carbonate, two parts by weight of metaborate are the equivalent of one part by weight of carbonate in normal developers.

Either we can use a strong alkali in weak concentration or a mild alkali in higher concentration. We shall obtain a more constant working and a better keeping developer by using a mild alkali"
-------

So, it is possible to use carbonate instead, just half weight (a really easy conversion!).
The only drawback being not as "constant".
A wrost keeping developer is not a problem, because I don't need it to be usable six months after mixing like XTOL.

This way, instant mytol could be modified to be:

- stock solution in water:
60 g sodium sulfite (anhydrous)
11.5 g ascorbic acid
0.15 g phenidone (pre-dissolved in alcohol)
3.5 g sodium carbonate
Water to 1 L

And I just need sodium sulphite (found locally) and phenidone (found online).
The only issue, being to keep the sulphite tightly closed, to prevent it becoming sulfate.
And there it is, a moderate grain low toxicity homemade developer, that (if close to XTOL) performs much better than Caffenol.

What do you think?

Rudeofus · Jan 25, 2018

I am sorry, but you are way off track here. Alkalinity of carbonate vs. metaborate is irrelevant if you have so much more Ascorbic Acid than Sodium Carbonate in your formula. This developer, as formulated by you, is likely going to be neutral/acidic and therefore mostly inactive. Personally I don't think you can formulate a decent PC type developer without a pH meter. Also note, that borate ion likely does more to ascorbate ion than provide alkalinity, so replacing it with carbonate may have unintended consequences.

elerion · Jan 25, 2018

Well, I just replaced 7g of metaborate with half its weight of carbonate, as the book recommended.
Instant mytol uses only 7g of metaborate, and more ascorbic acid. And it works.

In the same book "Developing The Negative Technique", there're some phenidone developers that use hydroqinone.

- stock solution in 1L water:
75 g sodium sulfite (anhydrous)
37.5 g sodium carbonate
8 g Hydroquinone
0.25 g phenidone
2 g potassium bromide
Water to 1 L

If you replace hydroquinone with ascorbic acid (at 60:1 ratio to phenidone, as a first guess), we could reach to the following formula:

- stock solution in 1L water:
75 g sodium sulfite (anhydrous)
37.5 g sodium carbonate
15 g ascorbic acid
0.25 g phenidone
Water to 1 L

This one DOES has more carbonate than ascorbic.

Note: these authors state that phenidone formulae requires a rather high restrainer content, thus the potassium bromide (and they also recommend Benzotriazole 1%).
But this is for phenidone-hydroquinone. These agents together are stronger than metol-hydroquinone.
Phenidone-ascorbic formulas I've seen, don't use potassium bromide. So a first try could leave the bromide out.

Rudeofus · Jan 25, 2018

elerion said:
Well, I just replaced 7g of metaborate with half its weight of carbonate, as the book recommended.
Instant mytol uses only 7g of metaborate, and more ascorbic acid. And it works.

Have you also compared the molar weight of metaborate vs. ascorbic ...

elerion · Jan 25, 2018

Metaborate is much lower.

Ascorbic acid (C6H8O6) is 176,124 g/mol
Metaborate (NaBO2) is 65,8 g/mol
Sodium carbonate (Na2CO3) is 106 g/mol

Rudeofus · Jan 25, 2018

So here we go: Instant Mytol suggests 11.5 g Ascorbic Acid with 7 g Sodium Metaborate, therefore you have a 0.065 : 0.106 = 1 : 1.63 molar ratio between Ascorbic Acid and Sodium Metaborate. In the soup you proposed, you have a 0,065 : 0.033 = 1 : 0.51 molar ratio between Ascorbic Acid and Sodium Carbonate ---> pH will be much, much lower.

If you want to create yet another MQ type paper developer, that "metaborate is milder so use twice as much as you't use carbonate" may work. With film developers strongly deviating from the beaten path it likely won't.

elerion · Jan 25, 2018

Got it.
So, I'd need 11.2 g of sodium carbonate, which leads to the same molar ratio as metaborate.
But then, I don't understand what the book states:
why is sodium carbonate stronger alkalii than metaborate, if you need more of it?
Also, Borax has a much higher molar weight, but is considered milder than metaborate.

People usually don't think in terms of molar weight.

lantau · Jan 25, 2018

elerion said:
People usually don't think in terms of molar weight.

Because ' people' usually only cook by recipe. A chemist thinks only in terms of how many molecules of each is required. Only at the end, when dumping the stuff into a bucket in the lab, are the numbers run to see how much is required.

So when you design a developer you'd think in mol only. Possible that your author came up with a few rough rules to play with minor modifications with limited scope, but once you go beyond that you end up on a public road and ideally drive by the rules to make sure it ends the way you want it.

Rudeofus · Jan 25, 2018

elerion said:
Got it.
So, I'd need 11.2 g of sodium carbonate, which leads to the same molar ratio as metaborate.
But then, I don't understand what the book states:
why is sodium carbonate stronger alkalii than metaborate, if you need more of it?
Also, Borax has a much higher molar weight, but is considered milder than metaborate.

There are concentrated and dilute alkalis, and there as weak and strong alkalis. Go through these courses here and learn about these important concepts, or all your developer experiments will be trial&error with strong emphasis on error.

Sodium sulfite, hard to get

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