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

Hi everyone,

Help! I tried to make a hot process soap out of bacon grease saved from frying bacon in the kitchen, but the finished lard soap stays caustic. Below is what I did. Could someone tell me what I did wrong ?[/B]I had 41.4 oz of bacon grease, (left from frying bacon). I cleaned it by rinsing it with very hot water a few times.

The lye I used was Roebic Crystal Drain Opener. This link describes this product: http://www.roebic.com/heavy-duty-crystal-drain-opener.shtml It's says "100% sodium hydroxide" on the bottle.

Here was my lye calculation:
(41.4oz) x (0.138 ) = (5.7132 oz lye) ... with no discount
(5.7132) x (0.96) = 5.4846 ... with a 4% discount

To double check my value, I used the lye calculator at thesage. It gave me the following: 10-16oz of water, 5.51 oz of lye (at 4% excess fat), for 41.4 oz of lard. I also used the lye calculator at brambleberry. It gave me the following: 13.66 oz of water, 5.485 oz of lye (at 4% excess fat), for 41.4 oz of lard.

So I used 5.5 oz of lye with 16 oz of distilled water.

Combining and cooking: I mixed the lye solution with the melted lard (not at the same temp) and mixed it with a powerful stick blender (mixing bit attached to an electric drill). After there was a light trace, I started to cook it in a crock pot in the low setting. The edges started to gel and the gelled areas started to expand toward the center of the mixture. Even after 4 hours of slow cooking, the phenolphtalein was still quite red (ie caustic). I thought it is supposed to get less alkaline the more you cook it. I ended up throwing vinegar into it and throwing the batch out.

Your input and advice would be quite helpful.

You should have done a zap test with your tongue, phenolphtalein will show red when the PH is above 10(I think) which is exceptable for soap and doesn't mean its still caustic. Soap is naturally high in PH, I bet your soap was just fine.

"...Even after 4 hours of slow cooking, the phenolphtalein was still red (ie caustic)...."

Overall your recipe and method looks reasonable, so lets move on to why you think the soap was lye heavy. What source of information did you use as a guide when trying to test your soap with phenolphthalein in this manner? It's something I see people doing, but it makes no sense to use phenolphthalein in this way. I think it leads to false positives -- in other words, your soap may well have been perfectly fine.

In a dilute solution, phenolphthalein (aka PhPh or phenol-p) is colorless below about 8.2, turns pink about 8.2, turns bright fuschia about 10, and above 12 will flush fuschia at first, then fade to colorless. A lard soap is made of mostly palmitic and oleic acids and the natural pH range of soap with these fatty acids is roughly 9 to 11. So, yeah, PhPh could easily indicate the pH is "high" for a lard soap. But it's not necessarily an unsafe pH -- it may well be a perfectly normal pH for the type of soap you're making.

If you're going to rely on PhPh as an indicator, then test the soap solution as a chemist would properly do it. From summerbeemeadow.com:

"...The proper way to use phenolphthalein is to dissolve some liquid or solid soap in a roughly 50:50 mix of distilled water and alcohol (ethyl or isopropyl rubbing alcohol is ok) in a clear glass. When the solution is as clear as it will get, add a drop or two of phenolphthalein solution and stir it. Then view it well-lit in front of a white background. This way, one can see the slightest little bit of pink color (which is ok) and all its graduations up to a deep red (definitely not ok)...."

But regardless of how you choose to test your soap, just be consistent with your method and practice often so you are quite familiar with how your chosen test works. Only with consistency and experience can you judge whether the results indicate a skin safe soap or not. If you don't have the experience to make that judgement and don't have an experienced soaper to help you, then back up your test method with a secondary test -- and I recommend the "zap" test.

Dampen your fingertip and gently rub it over the surface of the soap. Lightly touch your fingertip to your tongue. If the soap is excessively alkaline -- not skin safe -- the sensation you will get will be like a static shock or a "zap" from a battery. The sensation is sharp, unmistakable, and immediate. If you get a salty, metallic, or bitter taste ... that is not a zap. If you wonder if you got a zap ... it's not a zap. If you get a bland or "soapy" taste ... it's not a zap. If you do get zapped, rinse your mouth with fresh water. If you didn't get zapped, feel free to lick your soap to your heart's content (or not)!

I have used the Roebic Lye for every batch I have made thus far. And I have had no problems with it. Good air tight bottle and performs well.

I zap test my soaps. I am still waiting for my pH meter. Apparently it got back ordered. I will probably continue to zap test my bar soaps even after I get it. It is, to my mind, the definitive safe/not safe test.

That's a shame that you threw it out, even if it was caustic (which i dont think it was), you can still save it.

I agree with DeeAnna, i prefer to rely on my tongue to test.

From what you describe, I don't think your soap was caustic. I would suggest you try it again, pour the soap, and after a week or so, try washing your hands with it. It will not be totally cured at a week, but it will be safe enough for hand washing.

What kind of scale did you use? Was it a scale that measures in decimals, and could accurately measure 5.5 oz?

Is there a reason that you chose the 4% superfat? The "standard" superfat (using the term loosely!) is between 5% and 6%. Some soapers use higher, but not many go lower than that, unless they have a specific purpose in mind.

Gaspar I'm new to soap so I can't comment on your recipe or this experience but I have to say I'm impressed that someone made soap with bacon grease.

I agree with the advice given already. I also only rely on the zap test. I've heard many say that PH strips and meters are not accurate for CP/HP soaps.

Is it possible that the bacon fat was more than 4% "other stuff?" Bacon fat out of the pan isn't pure lard - and the description you used of cleaning it sounds like it's probably less thorough than the multi-step process generally used to turn animal fat into tallow/lard.

Thanks everyone for your prompt replies:

To everyone:

The reason why I was looking for clear phenolphtalein is in this video.
Go to (6:18 ) in this video to hear about Phenolphtalein use from "Suds & Buds": [ame]http://www.youtube.com/watch?v=Yg6tEa9hGFE[/ame]
The video seemed reasonable to me so I went by it. Perhaps there was a mistake; I'm new to all this.

Several soapmakers were very retiscent about doing the zap test. That's what discouraged me away from it. But I suppose it can be done if it passes the solution test that DeeAnna described. If one does the zap test regularly, over the course of time, don't you begin to ingest appreciable amounts of NaOH ?

I learned quite a bit from your replies. I wasn't expecting people to say that my process seemed ok.

To DeeAnna:

Okay I will try the water & alcohol solution test. I was just putting a drop of phenolphtalein on a sample of soap batter, and that drop was turning bright red.


To Obsidian:

The phenolphtalein person told me that phenolphtalein changes to pink above a ph of 9. Is it possible that there are different kinds of Phenolphtalein ? The Phenolpthalein that I have is used in high school chemistry classes and I believe is a powder diluted in an alcohol solution.

To Susie:

You mentioned a PH meter. I never heard of these. What is that ? How does it test the ph ? How reliable is it ? What are the price ranges ? Is there a website that talks about this ?

To dixiedragon:

The scale I used was a Pelouze SP5 scale. 5lb capacity. Measure to tenths of an ounce or in grams. Here's a link describing the scale:
http://www.amazon.com/dp/B00006IACE/?tag=skimlinks_replacement-20

I chose 4% lye discount because I was wondering whether or not my soap would become too oily with unreacted fat at higher %s. I don't want to put fats & oils on my skin. Is it too low ?

To MsMolly65:

Thanks. There is someone in our household that likes bacon. I thought it would be a shame to waste the bacon grease.

To songwind:

I was wondering exactly the same thing ! When one cooks bacon, one naturally uses alot of heat. Could the heat have partially broken down the lard into other sustances that do not react with lye ? If there was a significant amount of these other substances in my lard, that I might have been actually taking a sizble lard discount, which would have resulted in unreacted lye. I will search for a discussion on this.

Since this topic has come up again...

http://millersoap.com/phtome.html

http://jenorasoaps.blogspot.com/2013/05/ph-handmade-cold-process-soap-and.html

Because of the high pH of soap, phenolphthalein is of no real use, and it is nearly impossible to determine the exact pH. Because of the surfactant nature of soap, pH strips really don't work. And because soap is really only in suspension, not in solution, only a very good pH meter kept properly calibrated is of any real use. None of which tells you what you want to know since a perfectly good soap will always be alkaline!

If I understood your millersoap.com article correctly, there is one valuable thing (I think) that phenolphtalein can show.

If, and only if, it is clear then one can safely say the pH is below 10. Since it begins to turn red between 8.2-9.0.

If the phenolphtalein is pink or red, then it becomes useless since you now cannot accurately determine the pH.

At a dangerously high pH though the pheno-p will flash bright fuscia and then turn clear, so if that was missed it could be very bad.

"...If I understood your millersoap.com article correctly, there is one valuable thing (I think) that phenolphtalein can show...."

Um, the Millersoap article doesn't mention phenolphthalein once, so I gather you mean the Jenora article.

Honestly, looking at her numbers, the conclusion I drew is phenolphthalein is remarkably inconsistent and under-reports pH in this type of testing environment. Some quotes that show this inconsistency:

"Phenol looks around 8.5? Both pH strips look around 8 and digital pH reading is 9.69.
For the phenol (Phenolphthalein) test, from the pink, we can see they are over 8, but don't look over 10. ...With the digital ph metre, they both tested slightly over 10.
"Phenol makes the pH look quite low, the orange one around 8 or 8.5 and the lemon sea salt soap looks below 8! ...Then the pH [meter] tests the lemon sea salt soap in at 9.78! and the orange poppyseed soapover 10...
"Phenol looks around 8.5? Both pH strips look around 8 anddigital pH reading is 9.69.
"phenol, it looks like the pH is lower than 8, the paper strips look around 7 and the digital meter reading is 9.29

"...If, and only if, it is clear then one can safely say the pH is below 10. Since it begins to turn red between 8.2-9.0...."

If phenolphthalein is clear, the pH of a dilute solution is below 8.2. If it's fuschia then slowly fades to clear, the pH is above 12. If it's anywhere from pink to fuschia, the pH is between 8.2 and 12, with greater intensity of color correlating roughly to higher pH. And this should be done in a room temperature dilute solution of soap, water, and alcohol for best results -- not dropped on a paper towel wetted with soap solution, not dropped on a solid soap, and not dropped on a hot dab of HP batter.

PS: My huge thank you to New12soap for the links -- much appreciated!

Gaspar said:

If one does the zap test regularly, over the course of time, don't you begin to ingest appreciable amounts of NaOH ?

Click to expand...

Actually you are not ingesting the NaOH. 1) it has been saponofied and is no longer lye. 2) you are not swallowing the soap but will wash your mouth out typically and 3) you actually use lye in cooking.
http://sodium-hydroxide.com/caustic-preservative-crispy-food-all-you-need-to-know-about-lye-water/
4) see the thread on tooth soap, using soap rather than toothpaste

I know the first time I heard about the zap test I did not want to do it but I finally did and other than a nasty taste it wasn't HORRIBLE. Then I did get a zap. WOW! but it was over quick and I knew what I needed to do to save my soap. I never have to worry about running out of a chemical, or wonder if I read it wrong, I know instantly. It's no worse than giving you honey a quick kiss and static electricity zaps your lips. In fact that may be worse.

I zap test, mainly because I don't need anything that I don't already have for it! But also because you cannot tell from the pH if a soap is safe or not. Is 9 safe but 10 not? Or is 11 not safe? Actually, it's safe when all of the lye has turned to soap (saponified). It's unsafe when there is lye that has not saponified. You can't 100% tell that using the pH, so zap test is what I go on.

The Efficacious Gentleman said:

I zap test, mainly because I don't need anything that I don't already have for it! But also because you cannot tell from the pH if a soap is safe or not. Is 9 safe but 10 not? Or is 11 not safe? Actually, it's safe when all of the lye has turned to soap (saponified). It's unsafe when there is lye that has not saponified. You can't 100% tell that using the pH, so zap test is what I go on.

Click to expand...

Actually, ph 10 or above is NOT considered skin safe. Molecular breakdown is occurring, whether you're skin feels it or not. High ph and lye excess/heaviness are synonymous. The more soap is saponified/neutralized, the lower the ph will go until it hits its lowest point without breaking the soap back down. Over neutralization, where more lye is taken away, Wil cause breakdown. That begins at around a ph of 8-8.5.

For example mixing lye water, I'll use NaOH, with citric acid water will cancel each other out, thus neutralizing. 0.571oz of lye for an ounce of acid in 4 ounces of water each. Now in a 3rd cup, put equal parts of the 2 solutions. Right there you will have sodium citrate, and is neutralized. Now add more lye solution, your ph will rise. Add more acid solution, the ph will fall. Simple enough? In soap, neutralization for us is around 9, without break down. That's the general consensus in soap making. Even if you don't get your silly zap, it does not mean your soap is skin safe. Getting a zap or not can be indicitive of any number of other things. But that ph will tell you once and for all whether your soap is truly skin safe. Ive, and several others I've chatted with, had soap not zap me, but ph be too high.

Also, I'd covered many of the misconceptions brought about over phenol-p, which is pink, not red by the way (there is however a phenol-red) , strips and the thoughts of inaccuracy, in another thread:

http://www.soapmakingforum.com/showthread.php?t=43807

When I mentioned the mixing of the 2 solutions, I was actually just in my kitchen working on a small experiment to see if using potassium citrate (KOH + citric acid) would cloud my glycerin method liquid soap( it didn't), as I'm trying to find a way to lessen the amount of soap scum build up in my shower. I used my phenol-p drops to help me indicate if the combined solutions were in fact neutralized. After putting several drops on phenol in the 8 ounce solution, and it remained clear, I began adding more KOH. As the flakes hit, pink would show up, then immediately disappear. Only when I began to add more KOH to saturate my solution, did it begin to turn pink. Then i just went a little crazy to see HOW pink it would get. I got up to almost purplish red, before the color started to fade back to clear again as I continued to add more flakes, thus indicating the ph had gone above 12. So Phenol drops are quite accurate in indicating ph and lye excess in soap. Strips are as well, IF used properly. Just like reading ph strips for pool or aquarium water, where the instructions will say saturate the pads then wait X minutes before reading, but don't read after X minutes (usually 15), the same is said for soap. You have to let it soak on the indicator pads for a few minutes, then read it.

But, if you prefer to risk chemical burn to your tongue with the zap test, not like anyone can stop you. just keep in mind, zap test is not really going to tell you if your soap is truly skin safe, aside from the fact that there several variables that effect the zap test, leaving it's accuracy questionable as well.

If you are adding citric acid to interact with lye, you are effectively upping the superfat in your finished soap, as I understand the process.

It would be interesting to see how pH varies with % of SF/lye discount in fully cured soap. I have a pH meter but I haven't had the time to do an experiment like this.

To the OP, I'm sorry you threw out your soap. It was probably OK to use, or it might have been salvageable with a rebatch if there was some sort of measurement problem that was related to the relative purity of your bacon fat.

I pH tested my soap when I first began soaping and it ranged between 9-10.5 depending on the mix of oils I used. I don't pH test anymore.

lady-of-4 said:

Actually, ph 10 or above is NOT considered skin safe. Molecular breakdown is occurring, whether you're skin feels it or not. High ph and lye excess/heaviness are synonymous.

Click to expand...

Now you are making me feel a little queasy :sad: ...

My last three soap batches passed the zap test (no zap). So I took them to be okay, based on what people have told me. They are curing as we speak.

I also tested the pH of concentrated solutions of each with a laboratory pH meter. The meter said the pHs were 9.7 for the first, 9.8 for the second, and 10.1 for the third (that's around 10)

judymoody said:

If you are adding citric acid to interact with lye, you are effectively upping the superfat in your finished soap, as I understand the process.

It would be interesting to see how pH varies with % of SF/lye discount in fully cured soap. I have a pH meter but I haven't had the time to do an experiment like this.

To the OP, I'm sorry you threw out your soap. It was probably OK to use, or it might have been salvageable with a rebatch if there was some sort of measurement problem that was related to the relative purity of your bacon fat.

I pH tested my soap when I first began soaping and it ranged between 9-10.5 depending on the mix of oils I used. I don't pH test anymore.

Click to expand...

The following link, is what I'm experimenting with. I have only been making liquid soap since I began soaping 2 years ago. But it's still hot process, and honestly, what's in the link can apply to any method o0f soap making. LS just a little more forgiving.

http://forum.thesage.com/comments.php?DiscussionID=99

Gaspar Navarrete said:

Now you are making me feel a little queasy :sad: ...

My last three soap batches passed the zap test (no zap). So I took them to be okay, based on what people have told me. They are curing as we speak.

I also tested the pH of concentrated solutions of each with a laboratory pH meter. The meter said the pHs were 9.7 for the first, 9.8 for the second, and 10.1 for the third (that's around 10)

Click to expand...

I don't mean to make you upset about this. But it's a fact, that was stressed to me, not from a fellow soap maker, but from a friend with degrees in biomedical engineering, ie, she's a scientist. So I'm going to trust what she says, when it comes to the science of what we do, in the chemical sense, over another soap maker, to be quite frank. Stick with your pH meter. Make sure it's properly calibrated. If you can make adjustments to your soap, do so. If not, learn from it and apply what you learned next go round. The process of soap making is easy. But it is a science that not many folks understand, or even care to try to.

In this case, if you're doing hot process, and your ph is still a bit high, you can honestly mix up a neutralization solution and add it to your soap, thoroughly mixing it in. Then just cook it a little longer to remove the extra water you added in. Or you can leave it as is and go forward with the batch by putting in your additives like scent and color, then molding it. The little bit of water needed for a neutralization solution is so small, it will honestly further evaporate out as the soap cools and sits out for a few weeks, just like with CP. Meanwhile, you can still sfely use it, albeit it may be a bit soft.