Keeping Sodium Carbonate in anhydrous form

[Wayne]

Google and the CRC Handbook say the decahydrate effloresces into the monohydrate.

Well there's good news right there. It seems everything turns to mono so the OP can have his anydrous or decahydrate cake and mono it too. And I can keep letting my washing soda lay about without worrying about a thing

 

[removed account4]

a number of years ago i was in france and searched like mad for washing soda for my caffenol c made with " el gringo" coffee.
couldn't find it anywhere, pool supply / spa supply didn't have it, grocery stores didn't have it
the only place i could find it was at a pharmacy and it was exessively expensive. at the time
i had no idea i could have just gotten baking soda, which is available at any grocery store for almost nothing
and just spread it on a cookie sheet and put it in the oven at a low temperature like mike mentions to purge the water out
like gerald says, would have saved me time, effort and $$. here is a formula to
has a formula to figure out how much moisture is in baking/washing soda to adjust the g's used in solution

http://caffenol.blogspot.com/2010/03/soda-myth-and-truth_07.html might be helpful

if it was me, i'd just get whatever is available that is cheap, or baking soda, purge the water out / to dry it out more,
then keep the conversion handy and not sweat how much moisture might be in it by adding a little more to compensate ...

good luck !

 

[bernard_L]

Even if washing soda left the factory anyhdrous, wouldn't it quickly become monohydrate in those pasteboard boxes?

+1.
Listing in the MSDS as anhydrous is likely because, as far as the MSDS is concerned (no quantitative composition), the hydration state is immaterial. Also, in the time elapsed since this started, the OP would have had ample time to perform the little experiment with the oven to produce the anhydrous form (a bad idea imo) and find out what form he got from the pool/spa store.
Not only anhydrous spontaneously (when exposed to air) turns to monohydrate, as quoted above, also decahydrate turns to monohydrate, through efflorescence.

One more point: As listed in recipes, and as sold in photo supply stores,

• Sodium carbonate: monohydrate
• Sodium sulfite: anhydrous

See, e.g.: http://www.digitaltruth.com/data/formula.php?FormulaID=117

 

[Martin Rickards]

a number of years ago i was in france and searched like mad for washing soda for my caffenol c made with " el gringo" coffee.
couldn't find it anywhere, pool supply / spa supply didn't have it, grocery stores didn't have it
the only place i could find it was at a pharmacy and it was exessively expensive. at the time
i had no idea i could have just gotten baking soda, which is available at any grocery store for almost nothing
and just spread it on a cookie sheet and put it in the oven at a low temperature like mike mentions to purge the water out
like gerald says, would have saved me time, effort and $$. here is a formula to
has a formula to figure out how much moisture is in baking/washing soda to adjust the g's used in solution

http://caffenol.blogspot.com/2010/03/soda-myth-and-truth_07.html might be helpful

if it was me, i'd just get whatever is available that is cheap, or baking soda, purge the water out / to dry it out more,
then keep the conversion handy and not sweat how much moisture might be in it by adding a little more to compensate ...

good luck !

Baking soda is sodium hydrogen carbonate (sodium bicarbonate), which is chemically different from (di) sodum carbonate being discussed here.

 

[Rudeofus]

Definitely, the mono is FAR more common in the USA.

Is this still the case? My impression is that Kodak settled on monohydrate many decades ago for its superior storage properties, and they were huge back then, they would get whatever they wanted. Now, with photographic industry in shambles, monohydrate seems to have gotten out of fashion. Need evidence?

1. Photo Formulary charges a lot more for monohydrate ($55.95 for 10 pounds) than for anhydrous ($29.95 for 10 pounds), although anhydride contains more of the effective compound.
2. Arista's powder developers now use anhydrous: Aristadol, Powder Lith A&B, Premium Powder Film Developer
3. Same thing applies to powder developers from Legacy Pro: B&W Powder Paper Developer, Select Soft Paper Developer,

It looks like the monohydrate is a thing from the glorious past targeted mostly at legacy products who's makers didn't bother reformulating their stuff to the cheaper anhydride.

PS: This would explain the difference in Arm&Hammer product composition between 2001 and 2017. They would certainly be neither the first, nor the last maker consumer products, who quietly changes composition of their product lines to deal with shifts in raw material prices.

 

[Rudeofus]

Baking soda is sodium hydrogen carbonate (sodium bicarbonate), which is chemically different from (di) sodum carbonate being discussed here.

It has been stated here and elsewhere, that heating in an oven will convert baking soda into sodium carbonate. If you run out of Sodium Carbonate and don't have a local source for it, baking soda as a commonly available house hold product plus a baking oven can save the day.

 

[Gerald C Koch]

The monohydrate is the favored form since it is stable under normal humidity and temperature. However for powder mixes the anhydrous form must be used. Years ago when Bauman first came out with Acufine the first batch of cans started exploding on the store shelves. The monohydrate began reacting with other chemicals to form carbon dioxide. The developer had to be reformulated. Besides being a universal solvent water is also a universal catalyst. Few reactions in out everyday world can take place without a trace of water being present.

 

[Rudeofus]

However for powder mixes the anhydrous form must be used.

Kodak's Dektol used, and still uses the monohydrate, apparently without exploding packages or similar difficulties. Same thing is true for Formulary 106 Warmtone Powder Paper Developer.

 

[Gerald C Koch]

Kodak's Dektol used, and still uses the monohydrate, apparently without exploding packages or similar difficulties. Same thing is true for Formulary 106 Warmtone Powder Paper Developer.

Kodak owns a number of patents for the packaging of single mix powders. Perhaps that explains the difference. However companies like Ilford have to package a developer like ID-11 in TWO bags.

The following MSDS is more ambiguous citing both forms.

http://archpdfs.lps.org/Chemicals/Kodak-Dektol-developer.PDF

 

[Rudeofus]

Kodak owns a number of patents for the packaging of single mix powders.

Kodak certainly had some means to make the impossible not just possible, but also feasible and viable. Formulary, on the other side, is a small outfit, and doesn't have any of these options. I don't know their packaging, do they package all their raw ingredients separately?

 

[Gerald C Koch]

One of the patents involves the use of boric anhydride. A small amount of the finely divided powder is added to the developing agents. It coats them with with an acidic coating to protect them from the alkalis in the mix. It can also be used as a single pellet.

 

[Rudeofus]

One of the patents involves the use of boric anhydride. A small amount of the finely divided powder is added to the developing agents. It coats them with with an acidic coating to protect them from the alkalis in the mix. It can also be used as a single pellet.

Is this a process simple enough, that any small outfit can do this?

 

[RalphLambrecht]

As sodium carbonate monohydrate (the one I prefer to use) costs an arm and a leg in my country compared to anhydrous, I decided to switch to the later one.

How can I keep it in its anhydrous form and avoid the monohydrate conversion with time and moisture?
Will silica gel do the trick?

as I understand it,you buy anhydrous which turns into monohydrate over time and use the formulas written for monohydrate and then all is well and good.

 

[John Wiegerink]

Ralph,
I went through all the trouble of the oven/cookie sheet thing and the Baking Soda conversion to Carbonate, but finally said screw it. I just used the conversion table in the Darkroom Cookbook and called it darn good enough. It has a table that show how many grams of Sodium Carbonate Anyh. equals Sodium Carbonate Mono and visa-versa. Oh, and my results seem darn good enough also.

 

[Gerald C Koch]

Is this a process simple enough, that any small outfit can do this?

Protected by patent. Any business would have to license its use from Kodak. Ilford doesn't consider it important enough to do so. In principle it would not seem to be difficult. However not having read the patent itself I am not familiar with specific details such as particle size for the boric anhydride, mixing equipment, etc. IIRC a few of the patents are mention in Glafkides.

 

[Gerald C Koch]

Ralph,
I went through all the trouble of the oven/cookie sheet thing and the Baking Soda conversion to Carbonate, but finally said screw it. I just used the conversion table in the Darkroom Cookbook and called it darn good enough. It has a table that show how many grams of Sodium Carbonate Anyh. equals Sodium Carbonate Mono and visa-versa. Oh, and my results seem darn good enough also.

If you have access to either form then there is no problem. One consideration is that since the sodium bicarbonate is USP grade the resulting carbonate would be of a high purity. Perhaps better for certain critical applications.

 

[Rudeofus]

Protected by patent. Any business would have to license its use from Kodak.

If that patent has been issued after 2000, then I wonder how they were able to use monohydrate before. If that patent is older, it is no longer valid, and anyone could use it. Could you post the patent number?

 

[Gerald C Koch]

If that patent has been issued after 2000, then I wonder how they were able to use monohydrate before. If that patent is older, it is no longer valid, and anyone could use it. Could you post the patent number?

My knowledge of the patent come from Glafkides.

 

[Rudeofus]

My knowledge of the patent come from Glafkides.

So let's safely assume that this patent ran out before I was born, or at least not long after. This could still be a process suitable only for very large scale manufacturing outfits, but until we see the patent we just won't know.

 

[Gerald C Koch]

So let's safely assume that this patent ran out before I was born, or at least not long after. This could still be a process suitable only for very large scale manufacturing outfits, but until we see the patent we just won't know.

A technology like this one was useful when developers were sold in metal cans which Kodak did some time ago. In today's market with its use of composite bags the advantage seems quite a bit less. As I mentioned Ilford does very well using a two bag system.

I have several cans of DK-50 which use a plastic separator to keep the developing agents from mixing with the Kodalk. So even Kodak did not always make use of the patent.