Troubleshooting help -- 100% tallow soap with heavy foam layer

[DeeAnna]

A person asked me for help with a problem and I don't have any answers for him.

He is an experienced soap maker. He is making a 100% tallow soap as a charity project using a donated commercial tallow meant for deep fat frying -- not an ingredient he has used before. One of the 3 batches he's made so far looks fine. The other two have problems -- one cracked badly and both have a thick layer of white, dry foamy stuff on top. Here is his description of the problem:

"I was gifted 100 pounds of tallow.... It is labeled as "shortening" and the ingredients are: "Beef fat, BHT, Citric acid, and dimethylpolysiloxane"....

"[O]n batches 1 and 3, there is a heavy layer on top of a fluffy substance that is similar to the white topping on lemon meringue pie....

"... I know what causes cracking in soap, but my concern is the heavy layer of froth that resembles in texture the topping on lemon meringue pie. I've licked it, and it's not lye...."

The recipe is 100% tallow, 25% lye concentration (3:1 water:lye ratio). Half beer and half water. No fragrance, no color, and no other additives. According to him, he didn't vary his recipe or method for the 3 batches he made. I don't know the specifics of his method -- for example, I don't know if he CPOP's or soaps hot or whatever. I've asked him for clarification.

I'm familiar with BHT and citric acid being added to commercial lard, so these ingredients are no surprise. I was less familiar with dimethylpolysiloxane, but I've learned it is a de-foaming agent that helps when fat is used for frying. Threads here on SMF, at Kathy Miller's website, and on the Soapcalc website confirm dimethylpolysiloxane should not cause problems with soap, so it doesn't seem that this is a cause for the odd foam layer.

I've attached photos of the three batches -- one cracked + foam, one foam, and one good.

Does anyone have any ideas about what might be causing this foam layer? I will be grateful for any advice or thoughts!

 

[Saponificarian]

Hi DeeAna. . Not trying to troubleshoot here because you are way way more experienced and way way more knowledgeable about these things.

Could it be the beer? Beer does foam right? Or maybe the alcohol was not totally burnt off? Or just maybe something in the beer is reacting with any of the other ingredients in the tallow. I would do two things if it were me, ditch the beer and increase lye concentration and mix to thick trace before pouring into the mod since the soap is plain(For a test batch). I have found out I get less issues with my soap once it's at thick trace but that's with Palm oil so MMV with tallow. Just thinking out aloud.

 

[earlene]

Kevin Dunn passed around a couple of soaps (at SoapCon2017) that had a feature he called 'brain cheese' that he and his students made on purpose and it sort of reminds me of the one with the foam on top. Or at least like it might look before the soap he passed around turned into 'brain cheese'. Since access to the slides and photos was limited to attendees who paid registration fee, I am reluctant to share a link here on the forum. But I am confident he would share those 3 slides with you, should you contact him directly.

In any case, he said the cause was heating the soap. In the case of the soap he passed around, the formula for the soap included sucrose (4 % oils weight in sucrose - 1000 parts oil to 40 parts sucrose by weight). The soap formula he and his students use they call 'Duck's Delight', which you may have read about. If not, it's OO, CO, Palm Oil and Castor. The formula he shared has a 4% SF but not sure if that matters so much as the heat application.

They Oven Processed the soap at 150° F for 6 hours and the effect appeared after 3 hours. The effect was that the soap began to form a foamy layer which rose to the top as pure white soap even though all of the batter had been colored (a really pretty lavender). At the end of the 6 hours of the Oven Process, the soap had a distinct look of the inside surface of a geode, but waxy like a candle or well gelled soap. They also made the soap without any added colorant and the top layer seems to be a brighter white than the bulk of the soap.

Anyway, he said it had to do with the sucrose (as opposed to sugar in general) and the prolonged heat. And he may have said something more about the actual chemical reaction that occurred, but I don't think I took sufficient notes to be able to explain or understand. And his slides don't go into detail as to why.

As it relates to your friends soap I wonder if my impression, which could be wrong of course, is that when it first begins to rise to the top, this layer starts out foamy and much smoother or 'flat'. Then as the prolonged heat is sustained it continues to form what Kevin called 'Brain Cheese' (which as I say looked like the internal surface of a geode.) I wonder if the combination of beer sugars and perhaps a bit more heat with that one loaf, may have produced the foamy top, but then it began to cool down and didn't go any further.


One of these days I intend to try it myself (Kevin Dunn's experiment) and watch the process to see how the surface develops over time.

 

[Nao]

I have got that foamy stuff on a couple of my single bar batches too but I thought it was just that a lot of stuff starts to foam when there is a lot of movement, like sea foam, and if I just waited to pour until the foam had settled or just mixed it in into the batter there wouldn't be any problems with it showing up on the surface of the soaps.

I think I had that foamy layer on my beer soap too but I didn't take notes so I can't be sure, but there was no beer in the single bar batches so at least beer shouldn't be the only reason for the foam showing up.

 

[bumbleklutz]

I've had this happen once before. I didn't know what to call it, but I like the term "brain cheese".

I can't be sure what caused it, but when it happened to me, it was when I first started adding sugar to my batches. Additionally, I was using high water (25% lye solution) AND I was soaping WAY too hot. The batteries in the instant read thermometer were dying, and I didn't bother to double check the temps by touching the soap pot or the lye container. To make matters even worse, I CPOP'd those logs.

Two of them cracked, one got alien brains, but the last one had that foamy lighter colored stuff on top like the pictures. I'm not sure if it's relevant to this issue, but the one that got the foamy stuff was a small log mold that holds about 1.25# of oils. Maybe because of the smaller size it was able to heat up even more than the others.

I know that correlation and causation are not the same thing, but if I had to guess; I would guess sugar + high water + too much heat = brain cheese. :cry:

 

[DeeAnna]

My heartfelt thanks to you all! You've shared lots of good suggestions and useful experiences.

Thankyouthankyouthankyou!

The guy who's having problems is not being very helpful about sharing his soap making method, so I still have no idea how hot he soaps, whether he does CPOP or insulates the soap in the mold, or whatever. But most of us have learned that beer (or other sugary additives) cause extra fast heating during saponification. And we also know he's using a LOT of water (25% lye concentration). Both of these factors together sets the stage for overheating.

Here's what I told him, based on your thoughts --

"I've got some responses and suggestions from other soapers who have seen similar things on occasion. The "foam" may be a super heavy ash as Clara Lindberg (Auntie Clara) has suggested or it may be a foamy soap.

"The soapers who have seen something similar report that the foam layer doesn't replicate consistently, so don't expect to see it every time. One soaper said the foam actually formed in the soap pot. She just waited until it mostly subsided before pouring the soap into the mold.

"I can't provide an explanation. I can say it is probably not related to the fats in the recipe, but it does seem to be related to excessive temperature and water content. As Clara Lindberg has showed on her blog, these conditions increase the chance for cracking, weird textures on the top of the soap, and general overheating. And apparently for foam when conditions are exactly right.

"So I'd use a higher lye concentration -- I'd definitely recommend using a 33% lye concentration (2:1 water:lye ratio). A 3:1 ratio (25% lye concentration) is plain too much water for a CP method, foam or no foam.

"Also, soap as cool as is reasonable given this is a tallow soap, do not CPOP or insulate the mold, use a fan to cool the mold if you see signs of overheating (expansion of soap in the center of the mold, cracks, orange peel texture, etc.), and nix the beer or any other "heating" additives.

"Another suggestion, since the soap is a simple plain recipe, is to mix the soap to a definite visible trace before pouring, rather than pour at emulsion. Since you have not shared any details of your method, I have no way of knowing what you're actually doing. But pouring at visible trace will also give you the time to see if the saponification reaction is proceeding more normally before you commit to putting the batter in the mold.

"See if going back to these basics will get your soap back on track."

 

[0115d8cf]

'Brain cheese'? Oh man, that's unappetizing. Really interesting stuff, though! It's nice of you to help someone that's being so reluctant to give details.

 

[DeeAnna]

"...reluctant to give details..."

Yeah, this happens quite a bit.

A lot of soapers who ask for help simply don't realize they need to explain the problem fully. Not everyone is good at analyzing and describing problems, but it's a skill that can be learned.

I get the feeling some are too lazy or too scattered mentally to be willing and able to type it all out.

Other people jump to quick conclusions and then ask for help. With that "my mind is made up" attitude, it's hard for a person to see the point of sharing information that doesn't fit into their preconceived notions. Once we wrestle ALL of the facts out of the person and carefully pick the issue apart, it often turns out the REAL problem is something entirely different than what they thought was the problem.

Still more want to act cagey, as if their soap making method is proprietary information. As if I'd even want to do what they're doing -- they're the ones having problems! :think:

 

[dixiedragon]

"...reluctant to give details..."

Yeah, this happens quite a bit.

A lot of soapers who ask for help simply don't realize they need to explain the problem fully. Not everyone is good at analyzing and describing problems, but it's a skill that can be learned.

I get the feeling some are too lazy or too scattered mentally to be willing and able to type it all out.

Other people jump to quick conclusions and then ask for help. With that "my mind is made up" attitude, it's hard for a person to see the point of sharing information that doesn't fit into their preconceived notions. Once we wrestle ALL of the facts out of the person and carefully pick the issue apart, it often turns out the REAL problem is something entirely different than what they thought was the problem.

Still more want to act cagey, as if their soap making method is proprietary information. As if I'd even want to do what they're doing -- they're the ones having problems! :think:

"Hey, I made some soap with this stuff and it acted weird. What caused that? What do you mean, you have no idea. I thought you were an expert!"

 

[cmzaha]

I would say that I do not believe it has anything to do with his shortening, since the 50# cubes of tallow shortening I use include the same ingredients and I love it. It is pure white with no odor. I am thinking maybe the high water

 

[NsMar42111]

I thought it was a really thick layer of ash when I looked at it?

I've had something similar happen when a FO caused the batch to overheat but it wasn't that thick!

 

[Nao]

I don't want to sound to sure of myself since my experience is more on the limited side, but I'm questioning if it really is the water that's the problem, my single bar batches that got foam on top was made with 33% lye solution. I also don't really have any argument for why it should work, but the suggestion to mix to at least light trace before pouring to avoid the foam sounds very right in my head.

 

[DeeAnna]

I'm not sure if it's ash or if it's a foamy soap. It could even be both. Hard to say without having some in hand to look at. Not even the Andalusian castile batches I made with lots of NaOH and lots of water didn't make ash like this.

He still seems rather set on the idea that the additives in the tallow are the culprit. I think anyway -- he's kind of hard to communicate with. Carolyn (above) and everyone else I've found who uses this type of tallow aren't having problems, so I don't think the additives are the source of his problem either.

He did reveal he is making the soap in 4 gallon (16 Liter) batches and mentioned, "...I may have soaped too hot, though... I have to melt my tallow down in the oven around 170 F. I wait a while for it to cool. But may be not long enough..."

After a brief "Well, duh!" reaction after reading this, I replied --

"... IMO, the initial batter temperature definitely needs to be no more than 120 degrees F. If the temp of my ingredients and/or the initial soap batter are around 170 F, I'm making liquid soap paste or hot process soap. For cold process, the tallow should be just warm enough to be completely melted and transparent, but only sufficiently warm enough to reach that state. That's going to be about 110 F for tallow. If you must melt at 170 F, why not set a timer or use an immersion thermocouple so you can pull the fat out before it gets so hot? If you're making 4 gallons of soap, it would be a good idea to have more precise control of your process...."

One thing I do know is that soap does generate gas (probably water vapor) if it gets too hot and goes into a hard gel. That's basically what's causing the proverbial soap volcano. You can use this behavior to make a floating soap by carefully melting soap with very little water. Wait long enough and it will reach a temperature where it foams up. Put it in a mold at that point and, voila!, floating soap. With a high-water recipe and starting so very warm, it's possible that conditions are just right to make this foamy top layer -- kind of a slow-motion volcano that never entirely erupts. But that's a guess on my part -- I did not share this info with him.

He describes himself as an experienced soaper, but I wonder if he just knows a given rote method of making soap that works for him and not a whole lot more. I am thinking it's likely that he will ignore our collective advice, but I'd love to be proven wrong. I hope he gives our suggestions a try.