Citric Acid in Zany's no slime castile?

[szaza]

A few weeks ago I made Zany's no slime castile and really like it, except I get a lot of soap scum with my hard water. I generally add 2% citric acid to my water before adding the lye, but since the recipe has sodium bicarbonate in the 'faux seawater' I left the CA out this time. In a next batch I'd like to use CA, but I'm wondering what would be the best way to add the CA and make sodium citrate. I thought of 2 options:
Either adding the CA very slowly to the faux seawater so it gets time to react and fizz without bubbling over. I'd add some extra sodium bicarbonate to make up for the bicarbonate that reacts with the CA. With my very basic chemistry skills I calculated I'd need about 13,13g extra sodium bicarbonate for every 10g of citric acid. Can anyone verify if my calculations are correct? I don't think measurement of the sodium bicarbonate needs to be super precise for the faux seawater, but it would be good to know if I'm not too far off..
The other option is masterbatching the lye in a 50/50 solution with the CA added before the lye and adding a more concentrated version of the faux seawater after the lye has been dissolved. This seems like a lot more work and I don't think there is a benefit of doing it this way except it doesn't fizz as much and I know how to calculate how much lye reacts with citric acid

 

[Steve85569]

I would react the citric acid in water before making the faux sea water. That way you are not changing the lye discount ( superfat) in your recipe.

 

[szaza]

Hmmm.. not sure if I understand what you mean, @Steve85569 ? citric acid dissolves in water but doesn't react with it, it needs to react with either lye or sodium bicarbonate to make sodium citrate. In both cases I'd add more of the reactant to make sure the amounts of sodium bicarbonate and lye remain the same in the recipe, so as long as my calculations are correct the superfat should stay the same.. or am I missing something?

 

[The Efficacious Gentleman]

I think he means to make sodium citrate first (react the citric acid with the needed amount of lye) and then make the rest

 

[szaza]

Thanks for explaining @The Efficacious Gentleman ! So that would mean making sodium citrate and then adding that to the faux seawater (before or after mixing in the lye? Would there be a difference?)

 

[The Efficacious Gentleman]

Well, water can only "hold" so much before nothing else will properly dissolve. So I would go lye -> sodium citrate -> salt.

 

[Steve85569]

I will actually react citric acid and lye ( sodium hydroxide) and then dry the liquid. That way I always have some sodium citrate for use in recipes.
EG hit the nail on the head.

 

[Dawni]

Well, water can only "hold" so much before nothing else will properly dissolve. So I would go lye -> sodium citrate -> salt.

And remember to strain.....

 

[szaza]

Thanks for explaining. Having sodium citrate on hand seems like a good idea! And if I can make a bunch at the same time and store it, it will actually save time in the long run

 

[Steve85569]

Our local health food grocery store sells citric acid in bulk ( hint for finding it).
I use a clean pan to start reducing on low heat and once it gets thick ( rice pudding) I switch over to a parchment lined cake pan or other ridged oven sheet. When it's dry I carefully break it into the smallest particles I can. Looks like salt for some reason.

 

[penelopejane]

I am sorry but I don't agree with TEG's order of adding the additives.
I have found that if you add the lye first you will have a very difficult time trying to dissolve the salt and the citric acid.

Making neutralise citric acid (sodium citrate) then add salt then when they are dissolved add the lye.

My problem lies in the fact that Zany's recipe says mix the "faux salt water" then pour out the amount of water in the recipe. Doesn't this mean that you are using less water than the recipe states because you are just forgetting the weight of the salt, bicarb AND citric acid that has been added. So do you allow for this when you have added the citric acid? Or should you make the faux sea water measure out the amount of water required for the recipe and then add the citric acid required for the recipe?

Is this being too pedantic?

 

[szaza]

Hmm.. good point @penelopejane ! I've heared about salt not mixing well when added after lye.
I guess I could dissolve the citric acid first, add some lye to react with, use the reaction heath to dissolve the salt and sodium bicarbonate and lastly add the lye for the soap.
I get what you mean about adding extra water... I've wondered the same whenever I make soap with sodium citrate (which is always) and never really figured it out. I generally recalculate the water based on the overall amount of lye (for both soap and citrate), but I don't think that's the best wat to go about it..

 

[penelopejane]

Hmm.. good point @penelopejane ! I've heared about salt not mixing well when added after lye.
I guess I could dissolve the citric acid first, add some lye to react with, use the reaction heath to dissolve the salt and sodium bicarbonate and lastly add the lye for the soap.
I get what you mean about adding extra water... I've wondered the same whenever I make soap with sodium citrate (which is always) and never really figured it out. I generally recalculate the water based on the overall amount of lye (for both soap and citrate), but I don't think that's the best wat to go about it..

^^^ try that method (the order you listed). You will probably find swirls or dots of salt left in your bar. I aim for really perfect soap - no spots or swirls or glycerin rivers. But that is just me.

I just dissolve the salt and CA in the recipe water (heat it a bit if you have a problem) add the soda bicarb, then add the lye. I don’t think you have to worry about reacting the CA with the lye individually. It neutralises by itself. As long as you add the extra lye required to neutralise it and the recipe lye you are good to go.

I don’t add extra water over that required by the recipe. I use the exact amount so I can compare my lye concentratiions. A lot of people use extra tsps here and there to add colour etc but it makes my soft soap in the coloured sections or overall.

 

[szaza]

^^ try that method (the order you listed). You will probably find swirls or dots of salt left in your bar. I aim for really perfect soap - no spots or swirls or glycerin rivers. But that is just me.

Hmm.. do you think the lye will still prevent the salt from dissolving completely after it has reacted with the citric acid? That would be a bummer.. !
If I add the citric acid to the faux seawater it will react with the sodium bicarbonate that's in there right? Wouldn't I have to add more sodium bicarbonate instead of more sodium hydroxide in that case?
And do you think there would be a benefit of first adding salt and citric acid to the water before adding sodium bicarbonate? Instead of first salt and sodium bicarbonate (faux seawater) and then citric acid?

Thanks for all the help so far everyone!

 

[penelopejane]

I’m not a chemist but I think you are over thinking it. All the stuff will eventually react as you mix it together. I do not think the order matters. In ancient times they used sea water to make Castile then threw in a lemon as they stirred it.

I do know that however little salt you add to the lye/water mix after the lye has been added the salt and/ or the citric acid won’t dissolve or if it does dissolve some will precipitate out. This will show up as spots and swirls in your soap. If that doesn’t worry you go for it.

 

[szaza]

Haha overthinking? Me?
Ok so lye has to be added last, rest of the order probably doesn't matter. Thanks @penelopejane !

 

[DeeAnna]

If you make a brine from plain water and salt (NaCl), the mixture will be clear after the salt dissolves. If you then add NaOH, the liquid will turn milky if there is sufficient salt in the mixture. The milky look comes from the salt precipitating out (turning back into solid form) and creating tiny crystals. Those crystals are what creates the milky look. They will eventually settle out of the lye solution if you wait long enough. Just stir them back into the mixture and make soap.

The benefit of dissolving salt in the water first and then adding NaOH is that the salt crystals that are formed are very small. If you add the salt to the lye solution (salt after NaOH), the salt simply cannot dissolve, so a lot of the regular sized salt crystals will remain undissolved. Those crystals are large and make the white dots in the soap that PenelopeJane mentions.

This speckled look is fine in a salt bar -- that kind of soap is supposed to look that way. But it's not a good appearance in a solsiefe (brine) soap or a regular bar soap and can even be scratchy on the skin.

"...do you think there would be a benefit of first adding salt and citric acid to the water before adding sodium bicarbonate? Instead of first salt and sodium bicarbonate (faux seawater) and then citric acid?..."

No. It doesn't greatly matter as long as all these ingredients are properly dissolved. The goal is to add sufficient alkali to neutralize the citric acid as well as neutralize the fatty acids (to make soap).

Just a caution -- don't get carried away with adding a lot of bicarbonate. Sodium bicarbonate won't react with fat to make soap under the conditions in which we usually make soap. Only NaOH can do that job.

 

[penelopejane]

The idea of adding equal amounts of salt and soda bicarb to water might have come from a school science experiment to change the pH of water: http://www.carboeurope.org/education/CS_Materials/CarbonatesAndpH.pdf

Sea water has long been used to make Castile but the constituents of sea water can be found here:
https://law.resource.org/pub/in/bis/S02/is.8770.1978.pdf

As you can see Sodium bicarbonate makes up 0.2%.
That is a tiny tiny amount compared to the amount of salt.

So I don’t think Zanys recipe is trying to replicate sea water it is trying to change the pH and somehow speed cure. If it works for you, great.

Personally I don’t think you can really rush the cure of pure Castile. It’s like using a pressure cooker to cook a stew that traditionally takes 4 hours in the oven. The pressure cooker does the job but “something” is lacking in the final product and that is time. Time for time to do its magic.

 

[szaza]

Thanks for the tips and info @DeeAnna and @penelopejane !
I'm a bit apprehensive of adding extra NaOH, since the recipe has a 0% superfat..
Would it be an option to just wait a while after adding the citric acid and before adding the sodium hydroxide to be sure all the citric acid has reacted with sodium bicarbonate? Or would it be easier tot react the citric acid and sodium hydroxide separately and adding it to a more concentrated salt/bicarb solution?

 

[penelopejane]

Thanks for the tips and info @DeeAnna and @penelopejane !
I'm a bit apprehensive of adding extra NaOH, since the recipe has a 0% superfat..
Would it be an option to just wait a while after adding the citric acid and before adding the sodium hydroxide to be sure all the citric acid has reacted with sodium bicarbonate? Or would it be easier tot react the citric acid and sodium hydroxide separately and adding it to a more concentrated salt/bicarb solution?

You are not adding extra lye because you have to use lye to neutralise the citric acid. That means the extra lye will get eaten by the citric acid.

I add the salt then the CA then (if I was using it) I'd add the bicarb and wait until it is clear than add the lye because otherwise I get streaks in my soap.
You can dissolve CA in water then add the lye separately then add it to the other ingredients later. One problem with this method is that you have to weigh out small amounts of lye and water or masterbatch it. I just found it easier and reduced streaks in my soap to add in the order I listed above.

You have a lot of wiggle room even if you use 0% SF in a soap because your lye will not be 100% pure and the soap calcs are pretty generous. Lots of people on this forum have made -40% SF soap. Minus 40%SF soap. It was fine, honestly.