HP lard soap stays caustic. What did I do wrong ?

[FlybyStardancer]

Brambleberry has a tutorial on just this exact thing. Making a shampoo bar that has a super low pH, and is thus, much gentler on the skin, and hair, than regular soap.

Except that the addition of citric acid doesn't lower the pH. It increases the superfat and adds sodium citrate to the bar.

 

[judymoody]

I read that Brambleberrry thread in its entirety, and I am skeptical. Just because the author asserts that the end pH is 7, it does not make it so. I suppose I could attempt this recipe for myself and see for myself and I may just do that. But the conversation below if filled with errors on the part of the OP which gives me pause: for example, because the citric acid is added at trace, that will lower the pH as opposed to simply raising the superfat and producing sodium citrate. It is common knowledge (thank you Kevin Dunn) that soap batter at trace is still very active, saponification has barely begun, and adding 1% of citric acid then or upfront is not going to make a material difference. Also there is the dubious assertion by the OP that silicone molds "boil" the soap because it can't breathe. Last time, I checked coated freezer paper doesn't breathe, nor does wood. I have seen the pockmarking she describes in silicone molds when doing CPOP, but it has nothing to do with breathing.

While I think that the goal of more pH neutral soap is laudable, I have my doubts that this method is the way to go about it.

 

[lady-of-4]

Except that the addition of citric acid doesn't lower the pH. It increases the superfat and adds sodium citrate to the bar.

I read that Brambleberrry thread in its entirety, and I am skeptical. Just because the author asserts that the end pH is 7, it does not make it so. I suppose I could attempt this recipe for myself and see for myself and I may just do that. But the conversation below if filled with errors on the part of the OP which gives me pause: for example, because the citric acid is added at trace, that will lower the pH as opposed to simply raising the superfat and producing sodium citrate. It is common knowledge (thank you Kevin Dunn) that soap batter at trace is still very active, saponification has barely begun, and adding 1% of citric acid then or upfront is not going to make a material difference. Also there is the dubious assertion by the OP that silicone molds "boil" the soap because it can't breathe. Last time, I checked coated freezer paper doesn't breathe, nor does wood. I have seen the pockmarking she describes in silicone molds when doing CPOP, but it has nothing to do with breathing.

While I think that the goal of more pH neutral soap is laudable, I have my doubts that this method is the way to go about it.

^^This is how I can tell no one takes the time to actually look at the link I put up. Oh well.

Yes, when adding citric acid to any soap, be it a sodium soap, or potassium, the result is a salt of an acid, ie sodium citrate. And yes, if you add it on it's own to your soap, if will essentially superfat your soap, or really, you won't have soap at all. In that case, you are looking at a chemical reaction something like this:

Lye + Water + Fatty Acids--> Soap

Soap + Citric Acid--> Oils + Salt of Citrate + Water

In the post from The Sage Forum that I linked, once or twice even, it explains that in order to prevent the added citric acid from essentially taking lye away from the saponification process, in the attempt to lower the pH, you must use sodium citrate. Or create it by combining lye to citric acid in solution. The chemical equation is this:

Citric Acid + Sodium Hydroxide --> Sodium Citrate + Water + Heat
C6H8O7 + 3NaOH --> NaC6H5O7 + 3H2O + HEAT

Essentially, what you will do is 1 or 2 things: A) do a lye excess that will allow the acid to latch on and convert to a salt of citrate. or B) Discount your water just enough to set aside and create the appropriate citrate solution for your recipe, and add it at the beginning with your oils, or lye solution. Or add it in at trace. If you're doing a liquid soap, you have the aded advantage, once again, to wait unti your dilution phase to make the proper ph adjustments.

I've actually been working on this for the last 24 hours. Problem is, because I only have phenol drops, I cannot get a reading below 8.2. So far, my drops have come up clear after working with a 50/50 potassium citrate concentration, at 6ml of solution, added to 2oz of glycerin method liquid soap. The soap has also remained clear. There are other folks who are follow what I'm doing, and 1 lady is actually seeing what she can do with baking soda, which she found to thicken her soap immensely, while lowering her pH, and flat lining at 8.5 I can't remember if hers clouded or not. I'll be working again on this, later tonight, since I took the time to create a full range pH indicator... really nifty watching red cabbage juice change colors the way it did when exposed to different acids and bases.:grin:

 

[FlybyStardancer]

^^This is how I can tell no one takes the time to actually look at the link I put up. Oh well.

Maybe I didn't look at it when you posted it, but I had looked at that page before, several times in fact! She added it to the unfinished soap, which means it reacts with the lye to form the standard sodium citrate, increasing the superfat.

In order to get citric acid to lower the pH of an actual bar of soap, you have to rebatch once saponification is finished and add the citric acid at that point. That would be closer to the equivalent of adding citric acid to the dilution phase of LS.

Even then, you can only lower the pH of LS to the minimum required to keep the soap salts as soap. Once you start trying to lower it below that point, the soap falls apart (which is what causes the LS to be cloudy at that point). You can't just keep lowering the pH to what you want and still have it be soap.

 

[Gaspar Navarrete]

I am not trying to change the subject of this conversation - this is just a quick sidebar.

Instead of trying to test pH, why not test for any unreacted lye in the soap.

We still keep the zap test, by the way . The lye test would be a supplemental test.

 

[lady-of-4]

Maybe I didn't look at it when you posted it, but I had looked at that page before, several times in fact! She added it to the unfinished soap, which means it reacts with the lye to form the standard sodium citrate, increasing the superfat.

In order to get citric acid to lower the pH of an actual bar of soap, you have to rebatch once saponification is finished and add the citric acid at that point. That would be closer to the equivalent of adding citric acid to the dilution phase of LS.

Even then, you can only lower the pH of LS to the minimum required to keep the soap salts as soap. Once you start trying to lower it below that point, the soap falls apart (which is what causes the LS to be cloudy at that point). You can't just keep lowering the pH to what you want and still have it be soap.

You're back pedaling and repeating yourself, and not paying attention to what I wrote. I specifically said if you create a solution with lye and citric acid, that can be used as well. A salt of citrate is still created, anf lye used during the saponification process is left untouched.

And actually, yes I can continue to lower the pH to what I want and still have soap. I'm actually close to doing it. I've managed to lower the ph on one of my soaps down between 7 and 8. Because of my lack of a pH meter, I cannot get an exact number. My only testing mediums available were phenol drops and a red cabbage solution. Please goggle the latter.

 

[user 12568]

Just read through this entire thread... very interesting information indeed. (Deanna, I always enjoy your posts! You are truly knowledgeable, and I deeply respect that.)

All I have to add is this...

We might be talking science here, but lets not over complicate the basics. People used to render rancid fats kept over the winter months to make their soaps. They also used to float eggs in shoddy, unregulated lye water produced from ashes in their backyards to test if it was strong enough to use. So, let's face it, they really had no way of actually testing the PH of their soaps, nor do I think they gave a rats a$$. And they all lived,... molecular damage be damned! :crazy:

Just follow a tested recipe... zap test it... let it cure... wash your hands with it... shower with it... and declare it safe for general use.

Ugh! There's so much more to worry about in life. Like what scents I should add (and do they contain Phthalates), colours, swirls, embeds, molds... Oiy! Testing is the easy part...

Cheers!

 

[lady-of-4]

I am not trying to change the subject of this conversation - this is just a quick sidebar.

Instead of trying to test pH, why not test for any unreacted lye in the soap.

We still keep the zap test, by the way . The lye test would be a supplemental test.

No. I'm not getting into a talk about zap testing .

 

[The Efficacious Gentleman]

No. I'm not getting into a talk about zap testing .

I am, though, as it was one of the main topics. The pH was asked for in regards to safety, not just for poops and giggles. Therefore, the zap test must also be considered.

The zap test IS a test for unreacted lye.

We have already seen from the posts here that soaps are often above 10pH and are still considered to be safe soaps - by that, they are sold commercially with the pH levels clearly known and accepted and they have no noticable ill effects on the majority of people.

While it has also been said that soap with a pH over 10 causes skin damage, I think that we can't class soap as unsafe if it is over 10 in the same way that a lye-heavy/unreacted lye soap is unsafe as we can clearly see people using the former with no ill effects (most people, not all) but I don't think anyone could use the latter without skin issues.

So from that, it stands to reason that the pH is not the best way of telling if a soap is skin safe or not. For that, we do need to find unreacted lye. The best way to test that is to zap or use a variation on it:

I personally never put a new soap directly on my tongue. I wet my finger and rub a wee bit and wait. When nothing, I touch the soapy solution on my finger to my tongue. When nothing (other than a soapy/finger taste) I then touch the soap to my tongue. When still nothing, I consider it safe to use. After 2 weeks, I test it on myself and then at 4 weeks would consider giving it to people as presents.

It really depends on what you class as a safe or unsafe soap. I remember the OP was at one point talking about having a soap as safe as commercial soaps. From DeeAnna's post, that means you can go to well over 12pH and still be safe from that point of view, which is at odds with Lady-of-4 who classes anything over 10 as unsafe. When the OP speeks of unreacted lye, we come on to zapping, as commercial soaps don't have any unreacted lye - wouldn't zap you - but are way above 10 on the pH scale.

This is why pH for me is misleading and such a red herring. I will continue to use my little zap process mentioned above, as it tells me for a certainity if the soap conforms to my idea of safe or not.

 

[Dennis]

Enough.