# Sodium Carbonate instead of Sodium Hydroxide



## medic265 (Jul 12, 2014)

Hello Everyone,

Let me start off by saying WOW!  There's a lot of info here.  It's almost overwhelming for a beginner like me.  Thanks for letting me join and for sharing all this awesome information.

So I did a search for sodium carbonate and got 212 results.  But none of them really answered my question.

I know that sodium carbonate can be used.  But I didn't find any reference as far as how does it compare in the recipes to sodium hydroxide.  In other words is it used the same weight for weight?

The reason I'm asking is I have a 50lb bag left over from back when I owned a pressure washing company.  We used it to "heat up" some of our alkaline cleaners a bit when washing greasy equipment...

Thanks for any help you can provide...
Greg


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## seven (Jul 12, 2014)

do a quick google search on: sodium carbonate for soapmaking

you'll find quite a bit of info, including old threads from this forum on this particular subject.


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## scotsman (Jul 12, 2014)

Can sodium carbonate be used to make soap? I was under the impression that it was the hydroxide in potassium hydroxide or sodium hydroxide that fueled the chemical reaction. I am by no means a chemist but am really intrigued by this. Will be watching this thread to see what pops up. I'm always for new soap experiments that I can try. I keep a list in a notebook of soap ideas I want to try and unfortunately the list is getting so long that I'm afraid I will never get to everything. I've been making soap for quite a long while now and never seem to get tired of trying new techniques or ideas.


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## CanaDawn (Jul 12, 2014)

scotsman said:


> Can sodium carbonate be used to make soap?



I think that's exactly how that old Marseille soap TEG found would have been made.  Boiling with soda.


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## grayceworks (Jul 12, 2014)

Search for a thread DeeAnna answered that for me on.

Here it is:
http://www.soapmakingforum.com/showthread.php?t=42558

Specifically this post, but the whole thread is good
http://www.soapmakingforum.com/showthread.php?p=428100


And another that DeeAnna answered answered on:
http://www.soapmakingforum.com/showthread.php?t=37841


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## CanaDawn (Jul 12, 2014)

What I found re Marseilles soap was not only was it a boiled soap, but it was then washed with salt.

The bars were much larger than I had expected - not delicate little cubes, but a pound of soap in a big block.


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## medic265 (Jul 12, 2014)

Seven:
Thanks for replying....I did perform a google search.  That's how I found this forum....  :smile:  But I didn't go into reading the links very far which I need to do.  I was hoping it was more commonly used and that's why I posted the question here.  

Scotsman:
That's what a soap making friend told me.  When I figure it out I'll be sure to post what my findings are.

CanaDawn:
Thanks for replying.  Is Marseille an old brand?  I'll have to google that.

Grayceworks:
Thanks for replying.  I had  found those posts in my search.  They both talk about using the Sodium Carbonate and lime (I think it was lime) to make lye.  And that would work I'm sure.  But my friend was thinking that you could substitute the Sodium Carbonate for Sodium Hydroxide in whatever recipe you used.  He just was sure what the substitution rate was.  

Thanks for all the replies...
Greg


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## LunaSkye (Jul 12, 2014)

http://www.soapmakingforum.com/showthread.php?t=19129&highlight=sodium+carbonate

This link might be helpful.


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## medic265 (Jul 12, 2014)

LunaSkye said:


> http://www.soapmakingforum.com/showthread.php?t=19129&highlight=sodium+carbonate
> 
> This link might be helpful.


 

Thank you for replying.  I had read that link in my search also .  I also spent the last hour or so going through about the first 20 pages of the google search, about 400 links I guess.

I didn't find a single SC soap recipe .  There were several pages that described using the SC to "make" SH.  Really the only thing I found that I felt was positive was this LINK on ehow.com that says you can basically substitute SC for SH on a molar weight basis.  It does not however talk about using SC to make soap directly...

Maybe I should just try a very small chemistry experiment...

Greg


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## CanaDawn (Jul 12, 2014)

sodium carbonate and water react to form lye and sodium bicarbonate.  boiling would presumably be a catalyst.
Marseille soap is what The Efficacious Gentleman found in that other thread.  A very old type of soap.


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## medic265 (Jul 12, 2014)

CanaDawn said:


> sodium carbonate and water react to form lye and sodium bicarbonate.  boiling would presumably be a catalyst.
> Marseille soap is what The Efficacious Gentleman found in that other thread.  A very old type of soap.



THANK YOU!  Maybe that was stated in some of the threads I read but if it was I completely read right through it!  That's the exact info I was hoping to hear! :clap:  I'm gonna go back and see if I can find the breakdown of the amounts that will create (ie. 1lb in 10 oz of water makes 10 oz of lye and 6 oz of SB).  

Thank you very much!

Greg


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## CanaDawn (Jul 13, 2014)

http://www.soapmakingforum.com/showthread.php?t=47178

NaHCO3+NaOH <---> Na2CO3 +H2O

the weight of 1 mol NaHCO3 (baking soda) is 84.007g
the weight of 1 mol NaOH is 39.997g 
the weight of 1 mol Na2CO3 is 105.9885 g/mol

You have to do the chemistry, figure out molecular weights, and account for the buffering effect of the carbonate.  The reaction goes in both directions, the sodium bicarb has a buffering effect, and I think it is more complicated than just figuring out weights.  The heat and buffer have to be taken into account, but I don't know enough to advise.


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## medic265 (Jul 13, 2014)

CanaDawn said:


> http://www.soapmakingforum.com/showthread.php?t=47178
> 
> NaHCO3+NaOH <---> Na2CO3 +H2O
> 
> ...




Thank you again for the generous information.  I have found more information HERE if anyone would like to read.  That link says something to the effect of dissolving 1 cup of Sodium Carbonate in 2 cups of water and 1 cup of lime in 2 cups of water, mixing those together, and then straining off the solids.  This will create a 50% (that's rough math but close I'd say) solution of sodium hydroxide.  The solids that are strained off are Calcium Carbonate which is chalk.  That is the jest of it but the link goes into a bit more detail.  I'm going to email my college chemistry professor tomorrow to see if he can help us out a bit.  And this all relates to the information found in a few of the links that were posted earlier in this thread.

Well I didn't really think this thread was headed in this direction but I'm very thankful it did.  And if this information all works out to be correct, which I'm feeling strongly that it will, then this may be a very economical way to make Sodium Hydroxide with what I think may be some fairly easy-to-find components.  

Thanks for all the replies and keep em' coming!
Greg


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## CanaDawn (Jul 13, 2014)

Really, all this has been covered in the thread that was linked earlier but here's another specific post from that thread - go read there for more
http://www.soapmakingforum.com/showpost.php?p=401372&postcount=8
Sodium hydroxide is not very expensive to purchase.


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## summerflyy (Jul 13, 2014)

CanaDawn said:


> Really, all this has been covered in the thread that was linked earlier but here's another specific post from that thread - go read there for more
> http://www.soapmakingforum.com/showpost.php?p=401372&postcount=8
> Sodium hydroxide is not very expensive to purchase.




But for me, since NaOH is a controlled chemical here in Singapore, this kind of helps me a little and see if I could make my own lye etc.


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## medic265 (Jul 13, 2014)

Again Thank You all for your responses.  While it was not the original intent of this thread to convert SC to SH, that is what you all have accomplished.  The last link for me was the final key to finish the process.  I must apologize for not reading that before.  When I went through the links originally I was looking for wither SC was a direct substitute for SH.  It didn't register with me at the time as that being a way to convert it.

I've not bought any SH in a good while but I know it's not terribly expensive.  If I remember correctly when I bought the SC it was maybe $8 for the 50lb bag.  If the price has tripled that would make it $18 in today's market.  I'm gonna guess that locally a 50lb bag of lime is probably no more than $12.  That makes a total of $30 for the two needed materials.  If my molecular weight math is correct I will be able to produce somewhere roughly around 46lbs of SH with that.  The Sodium Hydroxide will be diluted in water but if I'm careful with weighing all my components before and after I should be able to get a pretty close concentration.  I'm thinking that boiling the mixture to remove the water may be a somewhat dangerous and time consuming process so I'll probably just leave it in solution and dilute it more as needed.

So unless someone else has questions I think I've got all the information I need and will let this thread drift on down the line.  I really appreciate everyone's help!.  

Thanks
Greg


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