Baking Soda Question

Skiver101 · Nov 15, 2017

I have a product in the kitchen cupboard labelled - ''Bicarbonate of Soda''.
It's ingrediants are - '' Sodium bicarbonate - 100% ''

I want to make my own general-purpose paper developer.
I have all the other ingredients to make Ilford ID-33, as described on digitaltruth-photo's Formulas page.

Can I proceed directly with this available Sodium Bicarbonate, and which of the two weights should I use.
I can't tell if what I have available is anhydrous or not; or if it's suitable at all. I think it's the added ''bi'' in front of ''carbonate'' that is confusing me.
I'm thinking about just splitting the difference in weights and using 41 grams, as it's not for any important prints; just a first attempt at contact printing with very basic equipments. But it would be good to know for sure, so as to not have to do it twice.

JP

Anon Ymous · Nov 15, 2017

Sodium carbonate is Na2CO3. What you have is sodium bicarbonate, NaHCO3. You can't substitute the one with the other, you need to source some sodium carbonate.

Svenedin · Nov 15, 2017

Sodium Carbonate, is washing soda but the stuff sold in supermarkets may not be of sufficient purity for photographic use -I don't know.

pentaxuser · Nov 15, 2017

Great stuff for pancakes, tho' and not the kind the Sassenachs throw in the air from frying pans on Shrove Tuesday.

pentaxuser

removed account4 · Nov 15, 2017

hey jp
no need to worry or buy anything else
you can easily convert your baking soda into sodium carbonate.
spread some out onto a cookie / baking sheet and put it in an oven
in low heat. you just want to purge the water out of it / dehydrate it/
soon, you will have sodium carbonate you can use without issue.
if i had known about doing that, i would have saved myself a fortune years ago
i spent and arm and leg getting sodium carbonate at a pharmacy in france ...
it was pure! and i now have a nice big plastic container, but it was expensive.

have fun !
john

ps i use stuff from the supermarket all the time ( washing soda ), it works great
probably less effort and $$ to buy a box...

Skiver101 · Nov 15, 2017

Well thanks guys.
I think I'll pop round to the local shop and buy some more of the same stuff (it's only 60 pence for 100 grams), and then I'll try the drying process John suggested; that sounds like a winner.
Whatever is left over will be converted into pancakes, for sure...now where did I put the Honey ??

Wayne · Nov 15, 2017

jnanian said:
ps i use stuff from the supermarket all the time ( washing soda ), it works great
probably less effort and $$ to buy a box...

I vaguely seem to recall from previous threads that its not so readily available in Europe as it is stateside...but I dunno, never been there.

NedL · Nov 15, 2017

Wayne said:
I vaguely seem to recall from previous threads that its not so readily available in Europe as it is stateside...but I dunno, never been there.

I think I remember reading that too. We're lucky that "arm and hammer" washing soda is commonly available.

For a starting point in converting NaHCO3 to Na2CO3, a low oven like John said ( ~200°F ) for about an hour should do nicely if it's spread thin.
If you ever need dextrin, a similar approach using corn starch needs a hot oven (~400°F ) for 20 or 30 minutes, stirring occasionally!

EDIT: for future readers, see post below... 250°F is better for baking soda.

Gerald C Koch · Nov 15, 2017

From previous posts I know that washing soda is available in the UK. However it is the decahydrate so you would have to calculate what is needed for different recipes. What is available in the US is the monohydrate a fine white crystalline powder. The decahydrate consists of large ice like chucks which lose water to the air and develop a powdery coutting of the monohydrate..

Gerald C Koch · Nov 15, 2017

NedL said:
I think I remember reading that too. We're lucky that "arm and hammer" washing soda is commonly available.

For a starting point in converting NaHCO3 to Na2CO3, a low oven like John said ( ~200°F ) for about an hour should do nicely if it's spread thin.

You need an oven temperature above the boiling point of water. I use 250F when I do this. Washing soda is fine for print developers but for film developer such as the Beutler formula I use the dehyrated baking soda as it is very pure. Baking soda is USP (medicinal grade) and so very pure.

NedL · Nov 16, 2017

That's interesting. I mostly use sodium carbonate just a tiny pinch in the water to make sodium thiosulfate fixer for calotypes and salt prints. Both of these processes are notorious for being finicky and sensitive to contaminants. If I made up a batch from baking soda it would last for years and add a little more surety. Thanks!

bernard_L · Nov 16, 2017

Sodium carbonate is also used to increase the pH of pool water, e.g. to correct the effect of acidic (CO2) rain. Sold here in 5-kg (!) buckets; check if one of your neighbors could donate/sell you one pound of the stuff. I believe it's the monohydrate form.
Oh, just noticed you are in Scotland. Maybe not so many pools up north.

tezzasmall · Nov 16, 2017

I have bought numerous bags of Sodium Carbonate as Washing Soda in the UK over the years with no problems. And it's MUCH cheaper than converting Bicarbonate of Soda! And it's usually just a quid or two for a good sized bag.

I used to get it from Boots but they no longer stock a lot of things that they used to.

In Southend I get it either from my local corner shop or from a chain of Wilkinson's, so it's well worth looking on the shelves where ever you get your Bicarb from, as they probably will have Washing Soda to!

Terry S

Svenedin · Nov 16, 2017

tezzasmall said:
I have bought numerous bags of Sodium Carbonate as Washing Soda in the UK over the years with no problems. And it's MUCH cheaper than converting Bicarbonate of Soda! And it's usually just a quid or two for a good sized bag.

I used to get it from Boots but they no longer stock a lot of things that they used to.

In Southend I get it either from my local corner shop or from a chain of Wilkinson's, so it's well worth looking on the shelves where ever you get your Bicarb from, as they probably will have Washing Soda to!

Terry S

They sell it in Sainsbury's supermarkets with the other laundry stuff or sometimes with the cleaning products.

Skiver101 · Nov 16, 2017

Just finished the process of ''drying out'' the sodium bicarbonate.

Not being really sure of what I needed to do, I lined a 14x12x2 inch baking tray with clean foil; laid out and added 366 grams of ''wet'' powder and put it into a pre-heated oven set at 60deg.C for approx 1/2 hour; then 80 deg.C for approx 1 hour; and finally 100deg.C with fan assist for approx 3/4 hour; stirring and folding intermittently all the while.
Realising that I had no idea how to determine the rate of evaporation of the water molecules, I stressed about how long to leave it ''cooking'' ...I took the decision to mainly base my timing in relation to the smell being given off; as at first it did smell like someone was cooking pancakes. However, this odour vanished after the first hour. Whether this was actually what had transpired or not; I don't know.
On finishing the process of ''cooking'', and allowing a cooling interval, I then weighed the powder again...
...366grams now weighed in at 322grams. Apparently something had ''cooked off''...I just hope it was the majority of the water molecules, and that I am now left with 322grams of Sodium Carbonate (Anhydrous) as the developer recipe requires.
I'll know soon enough if it all worked...

Thanks for all the contributions, info, and tips.

JP

Anon Ymous · Nov 16, 2017

The conversion of bicarbonate to carbonate isn't the dehydration of a compound. Some water escapes, but carbon dioxide is also released. In theory, 168g of bicarbonate give 106g of carbonate. This means that the 366g you used should give you 231g of sodium carbonate. What you did resulted in partial conversion. Seriously, it's a fairly common compound and it would be much better and easier to just buy it. It doesn't mean that using bicarbonate will give a developer that won't work at all, but it certainly won't be as alkaline, so pH will be much lower, perhaps too low for a print developer. Finally, adding the right amount of sodium hydroxide (if you have it) will convert bicarbonate to carbonate. 40g of sodium hydroxide are needed for 84g of sodium bicarbonate and they give 106g of sodium carbonate. Adjust these amounts according to the quantity you need.

Skiver101 · Nov 16, 2017

Hmm, I hear you Anon Ymous...
I'd best not make more than 1 litre to test.
What about cooking off some more of what I have; if the final developer solution proves inadequate ?
There seems to be mixed messages coming at me, it's rather confusing. I guess the best path is to test.

JP

pentaxuser · Nov 16, 2017

I have to say I too am a bit confused and when you take into account the time for preparation, being there while it "evaporates", weighing the stuff again, the number of times you might have to do this and finally the cost of the electricity I do wonder if buying the right stuff isn't easier in the end.

pentaxuser

Gerald C Koch · Nov 16, 2017

When you heat baking soda to convert it to sodium carbonate the solid changes from a crystalline powder to a very fluffy solid. So if your resultant is fluffy then you are there. BTW don't worry about overheating it as you cannot drive off the remaining carbon dioxide you would need red heat to do this.

You need a glass, stainless steel or agate container for the heating process. Aluminum will be attacked by the carbonate.

It's really very simple to do, 1 hour at 250F should be more than adequate. What you get is far higher purity than washing soda. So it is worth it especially for ascorbate film developers since iron is a common impurity of washing soda. Remember the Fenton reaction which is catalysed by iron ions.

Skiver101 · Nov 16, 2017

pentaxuser said:
I have to say I too am a bit confused and when you take into account the time for preparation, being there while it "evaporates", weighing the stuff again, the number of times you might have to do this and finally the cost of the electricity I do wonder if buying the right stuff isn't easier in the end.

pentaxuser

Great comment, and so helpful. Thanks.

john_s · Nov 16, 2017

Gerald C Koch said:
When you heat baking soda to convert it to sodium carbonate the solid changes from a crystalline powder to a very fluffy solid. So if your resultant is fluffy then you are there. BTW don't worry about overheating it as you cannot drive off the remaining carbon dioxide you would need red heat to do this.

You need a glass, stainless steel or agate container for the heating process. Aluminum will be attacked by the carbonate.

It's really very simple to do, 1 hour at 250F should be more than adequate. What you get is far higher purity than washing soda. So it is worth it especially for ascorbate film developers since iron is a common impurity of washing soda. Remember the Fenton reaction which is catalysed by iron ions.

The instructions I have read for this process usually stipulate a tray on which the sodium bicarbonate is spread, as if the process was like drying out.

For those of us whose ovens are not quite as clean as they might be, would something like a conical flask offer better protection from traces of food that might settle on a tray of sodium bicarbonate? Obviously the water vapour and carbon dioxide would have to be given a chance to escape but the reaction seems to be not just a "drying out," a process that would be encouraged by spreading out. Perhaps giving the flask a decent shake a few times during the process might help the gases to dissipate.

NedL · Nov 16, 2017

Gerald C Koch said:
...... iron is a common impurity of washing soda.

Oh crap, I didn't know that. Doing this or buying some pure sodium carbonate just moved to the "todo soon" list. It's also possible that sodium bicarbonate might work just fine for my application.. I just need to make my hypo slightly alkaline.

Gerald C Koch · Nov 16, 2017

john_s said:
The instructions I have read for this process usually stipulate a tray on which the sodium bicarbonate is spread, as if the process was like drying out.

For those of us whose ovens are not quite as clean as they might be, would something like a conical flask offer better protection from traces of food that might settle on a tray of sodium bicarbonate? Obviously the water vapour and carbon dioxide would have to be given a chance to escape but the reaction seems to be not just a "drying out," a process that would be encouraged by spreading out. Perhaps giving the flask a decent shake a few times during the process might help the gases to dissipate.

A conical flask (Erhlenmeyer) and the Florence flask were so designed to trap steam and prevent evaporation. Therefore not the best choice. Most households have a glass baking pan which works fine. Baking soda will not hurt it and is nontoxic.

Skiver101 · Nov 17, 2017

Hey Gerald...
I re-cooked at the higher temperature (250F) in a pyrex dish as you suggested (and is noted by NedL), and have now reduced the weight from the original 366gms to 237gms - very close to what Anon Ymous estimated (231gms).
I think I'm now good to go.
Thanks all for the input.
JP

Anon Ymous · Nov 17, 2017

Sounds about right, I'd use it.

Baking Soda Question

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