# Dissolving salt

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#### gsc

##### Well-Known Member
Does anyone know how much water it would take to properly dissolve 2.45 ounces of lye AND 1.55 ounces of salt (putting both in the same container)? Is there a formula for salt and lye absorbtion?

#### DeeAnna

##### Well-Known Member
What are you trying to do -- make a solsiefe (sp?) soap?

#### Susie

Supporting Member
You use the proper amount of water called for on the lye calculator. You dissolve the salt first, though.

#### BrewerGeorge

##### Well-Known Member
In general at roomish temps of 20C, 100g of water will dissolve about 36g of NaCl. So roughly 7 fl. oz. of H2O for your 2.45 oz. of NaCL.

#### gsc

##### Well-Known Member
Yes I am trying to make a brine soap. I was using a calculation of 25% salt to my water but there was a LOT of salt that would not dissolve. However I was dissolving my lye first then the salt. I was also trying to use 50% coconut water and 50% water.

#### Obsidian

##### Well-Known Member
You have to dissolve the salt first then the lye. Once you add the lye, the solution will turn white and stay that way. There will probably be a weird sediment but that's normal. All is good as long as the lye crystals dissolve.

#### DeeAnna

##### Well-Known Member
Add salt to the water first to get the salt fully dissolved so there are no scratchy grains left behind. NaOH is added second to the salt-water mixture. The white precipitate that happens after adding the lye is fine particles of salt coming out of solution as the NaOH changes the solubility of the salt in the water-NaOH-salt mixture. It's fine -- keep it stirred up and use the mixture just like that.

#### The Efficacious Gentleman

You might not be able to use 50% water, 50% milk. You need enough water to dissolve the salt and the lye , so if you are looking for your total liquid to be a little bit low then you could struggle and over saturate the water.

I'm not sure if you could dissolve the salt in the milk part and the lye in the water part........

#### Susie

Supporting Member
You might not be able to use 50% water, 50% milk. You need enough water to dissolve the salt and the lye , so if you are looking for your total liquid to be a little bit low then you could struggle and over saturate the water.

I'm not sure if you could dissolve the salt in the milk part and the lye in the water part........
That is how I would do it. You will have to slowly add the salt to see how much it would take. There is only so much salt that amount of liquid will dissolve.

#### DeeAnna

##### Well-Known Member
I can't give an answer to the question the OP asked -- exactly how much water-based liquid is needed to "...dissolve 2.45 ounces of lye AND 1.55 ounces of salt..." Most soapers just take the tack I and others have described and understand that some of the dissolved salt will precipitate back out of solution after the NaOH is added and shifts the solubility of the salt in the mixture.

I suspect you would have to use more than "full water" (a lye concentration below 28%) to get a perfectly clear mixture with no precipitated salt, but that's not practical from a soap-making standpoint. We'd have to have a solubility chart of salt-NaOH-water to know for sure.

It makes little or no difference if you dissolve the salt in one portion of water-based liquid and the NaOH in the another separate half and then use the two to make a batch of soap. That's like putting chocolate in a 1/2 glass of milk and strawberry in the another 1/2 glass and hope the two won't mix together in your stomach when you drink each 1/2 glass separately. When you combine the two portions of liquid with the fat in your soap pot, some of the salt will still precipitate out. You just won't see it.

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#### The Efficacious Gentleman

I was just meaning that if the total liquid combined would be enough, but as the water is only 50% of the total, the water alone might struggle just a bit, but the milk is still there to use for dissolving. I suppose the other way of looking at it would be to dissolve all in the water alone and, if there is anything on the wrong side of saturated, the water of the milk could take it. Not to be used for increasing the amount of salt beyond the normal amount for a brine soap, but just to allow for the split nature.

I suppose the question would then be - how much could the milk take, as I would think it would be less than the same amount of water.

#### BrewerGeorge

##### Well-Known Member
I can't give an answer to the question the OP asked -- exactly how much water-based liquid is needed to "...dissolve 2.45 ounces of lye AND 1.55 ounces of salt..." Most soapers just take the tack I and others have described and understand that some of the dissolved salt will precipitate back out of solution after the NaOH is added and shifts the solubility of the salt in the mixture.

I suspect you would have to use more than "full water" (a lye concentration below 28%) to get a perfectly clear mixture with no precipitated salt, but that's not practical from a soap-making standpoint. We'd have to have a solubility chart of salt-NaOH-water to know for sure.
...
The difficulty is that these two suffer from the common ion effect with the Na in the lye interfering with the salt's solubility. I started setting up the problem yesterday - Ks and Qs - before realizing that algebra can only get us the equilibrium state at specific volumes and temps. Finding the amount of solution directly from the amount of solutes would require calculus, and I don't remember enough calculus.

Once I remembered that I can't even get 15g of salt in 200ml of water to stay dissolved after I add lye, I realized that as DeeAnna says, the amount of water required would not be practical for soaping.

Interestingly, KOH and NaCl should NOT suffer from that same common ion effect problem.

#### BrewerGeorge

##### Well-Known Member
If you have a Google account you can enter your recipe to check for Maximum Salt Amount.

That's the amount of salt that can be dissolved by itself. Most of that salt will drop from solution when you add the lye. But dissolving the salt first does does have a big impact. The solid salt that will end up in the soap will be tiny, tiny particles driven from the solution by the lye. Particles small enough to stay in suspension easily (making cloudy water) rather than dropping down to the bottom quickly. I suspect that this is the difference between the feel of soleseife vs a salt bar with solid crystal salt added to the batter.

#### TeresaT

##### I see you.
Add salt to the water first to get the salt fully dissolved so there are no scratchy grains left behind. NaOH is added second to the salt-water mixture. The white precipitate that happens after adding the lye is fine particles of salt coming out of solution as the NaOH changes the solubility of the salt in the water-NaOH-salt mixture. It's fine -- keep it stirred up and use the mixture just like that.
The difficulty is that these two suffer from the common ion effect with the Na in the lye interfering with the salt's solubility. I started setting up the problem yesterday - Ks and Qs - before realizing that algebra can only get us the equilibrium state at specific volumes and temps. Finding the amount of solution directly from the amount of solutes would require calculus, and I don't remember enough calculus.

Once I remembered that I can't even get 15g of salt in 200ml of water to stay dissolved after I add lye, I realized that as DeeAnna says, the amount of water required would not be practical for soaping.

Interestingly, KOH and NaCl should NOT suffer from that same common ion effect problem.
Is this true for sodium citrate as well? Or can water be too saturated with a single chemical to dissolve another chemical into it? I'm asking because I can NEVER get SC to dissolve in lye solution. However, I can always get NaOH to dissolve in a sodium citrate solution. Actually, now that I'm thinking about it, I can't get anything to dissolve in the lye solution. If I'm adding sugar to the soap and forget to put it into the water before I add the NaOH, I might as well leave it out because it will not dissolve in the lye solution. Even if it's hot. Is the NaOH making the water too "full" to dissolve anything else in it?

#### BrewerGeorge

##### Well-Known Member
Is this true for sodium citrate as well? Or can water be too saturated with a single chemical to dissolve another chemical into it? I'm asking because I can NEVER get SC to dissolve in lye solution. However, I can always get NaOH to dissolve in a sodium citrate solution. Actually, now that I'm thinking about it, I can't get anything to dissolve in the lye solution. If I'm adding sugar to the soap and forget to put it into the water before I add the NaOH, I might as well leave it out because it will not dissolve in the lye solution. Even if it's hot. Is the NaOH making the water too "full" to dissolve anything else in it?
Sodium citrate had the same common ion issues that simple salt has. It has to be dissolved before the lye. As for sugar, it shouldn't have the sodium ion problem, but I've had the same experience add you with not being able to get it to disolve into lye. I don't know why, but I know to do sugar first.

#### DeeAnna

##### Well-Known Member
I think sugar doesn't dissolve well in lye solution for another reason other than changing solubility.

Sugar reacts with lye to some extent, so when you add solid sugar crystals to lye solution, the instant reaction of the sugar with the lye will cause clumps to form that simply won't dissolve. It's a little like when I made the beginner mistake of dropping dry flour into boiling broth to make gravy -- the hot broth caused the flour to instantly formed clumps that never mixed properly to make a smooth gravy. When you dissolve sugar first in plain water, the same reaction between the sugar and lye still happens, but now the reaction happens on a molecule-to-molecule basis and that prevents the clumping.

#### Susie

Supporting Member
LOL, when I forget to add sugar to water first, I add honey to the oils.

#### TeresaT

##### I see you.
LOL, when I forget to add sugar to water first, I add honey to the oils.

I just say forgetaboutit!! I get my honey from a coworker that is a beekeeper. I'm not wasting pure gold on soap. I should probably go to the produce stand and buy "local" honey from strangers. I'll use home-harvested stranger honey in my soap. Not friend harvested, though. (And that makes no sense whatsoever, but Darren's fall honey is da bomb!!! I don't like the spring honey because I can taste the flowers, but the fall honey is amazing. I guess it's mostly grass and hay pollen.)