Curing

[cmzaha]

i know theoretically this sounds right but Pg 79 of Scientific Soaping by Dr Dunn says 3 things occur during cure. Evaporation, hardening, and leftover alkali is neutralized. Nowhere can I find him talking about crystallization changes. Has anyone tested the theory by imaging slices of soap over time?

I have seen the changes and it is very interesting. My granddaughter has looked at new fresh soap slices and old soap slices under her compound microscope and you can definitely see the crystalline structure change. Sadly, she did not get her camera connected to her computer after her previous computer crashed. I wanted her to send me the pictures so I could post the pictures here but I believe she forgot. Then life got in the way and we both forgot to pursue it.

 

[MrsZ]

The caveman chemisty link @amd linked above is written by Dr. Kevin Dunn, author of Scientific Soapmaking: The Chemistry of the Cold Process, so if you read that page 56 that @amd mentions, I think it is obvious that he is talking about a crystalline structure. And on page 73 of that same link, Kevin says, "The structure of solid soap is similar to that of neat soap, but the fatty tails of the soap molecules are “frozen” in a crystal lattice." That, too is a crystalline structure, as further stated by @amd above and supported by DeeAnna's explanation that @MrsZ linked in her response.

So I don't quite understand how a anyone could say, "Just read Scientific Soapmaking" and claim it proves the opposite of what Kevin Dunn says in his other information easily accessible online. I do have his book and have not found a contradiction to what he says on his Caveman Chemistry site. So if they can specify a particular quotation, page and reference in his book, I'd be eager to look it up. ETA: Saying that those 3 things happen as Microchick mentions above does not preclude the other things that Dr Dunn says in the Kevin Dunn soap lectures I have attended in person & pdf linked by amd in her first post in this thread.

Dr. Dunn has lectured extensively and not everything appears in his book in as much detail, as some of his lectures, so by saying something is disproved by its absence in a given book is ludicrous.

Here are a couple of links that address solids with or without crystalline structure:

https://opentextbc.ca/chemistryatomfirst2eopenstax/chapter/lattice-structures-in-crystalline-solids/https://chem.libretexts.org/Bookshe..._According_to_Its_State-_Solid_Liquid_and_Gas
The second talks about glass as amorphous rather than crystalline. So I suppose an argument could be made that soap is an amorphous solid like glass rather than crystalline solid, but even Kevin Dunn talks about the crystalline structure in the pdf @amd linked, so I am not sure that would reconcile. However, it is possible to convert a crystalline solid to an amorphous solid according to Britannica and other sources, and heat is part of that process. So I suppose that solid soap could become amorphous after the crystalline phase given sufficient heat.

Here is a link that shows how amorphous solids break versus how crystalline solids break, and I did once have a soap that fit that criteria quite dramatically. But does it all? I am not at all sure. I believe that one soap that broke like Obsidian (volcanic glass, an amorphous solid) breaks had something to do with the ingredients and how long I waited before attempting to cut the soap. But then, maybe that is a clue? I am unsure.

Although I am not a chemist, I am aware that something can start out with crystalline structure and end up amorphous solid and that amorphous solids can also be converted to crystalline solids (link). So is solid soap one of those things? Does it start out crystalline and stay crystalline? Or does it start out crystalline and become amorphous? Or are both or either possible depending on conditions? In the NIH article that I linked (a couple of sentences back), it states that both can co-exist, so could that be the case with soap?

I suppose that all are possible, but is it really that crucial to know or argue about? Maybe for the nit-pickers.

I should have studied chemistry a little better in school....

All this information is amazing to me. Thanks for sharing, I'm learning a lot. I'll be checking out the resources you provided a little later.

 

[Arimara]

I cannot agree with you more and have often wondered why the admins of these groups don’t correct the misinformation. I have tried to steer people in the right direction and usually get attacked for it! I keep quiet for the most part now (my tongue is too sharp). I’d end up getting kicked out.

If I were in such a group, I'd either leave or just get kicked out. I have no qualms about either scenario happening.

 

[SoapWitch]

I love this discussion! I'd like to add a few thoughts, first, I know "google" is now a verb, however, there are many other (search engines) ways to find things on the inter-webs that don't taint the soup, like DuckDuckGo, Brave and DogPile. With that said, it is really refreshing to read thinking people's comments.

I read, and then observe (if I can, clearly I cannot utilize a microscope to see inside the soap) to discover what seems true, at least a working hypothesis. With this said, when making soap, and then utilizing the soap dough aspect, I see on a small scale how soap that is easily pliable can dry, cure, and lock together becoming no longer pliable or soft. Small or large pieces take time to become hard. The drying process can happen more quickly the smaller the pieces (less water) however, the curing process still takes time. I dropped a six day piece of soap on the floor, a six month piece of soap and a six year soap and observed the results. A variety of dings, all varied in degree. So I ask, why?

I see this as "locking" or solidifying, becoming hard. That process, as I see it is water evaporation to allow for the molecules to come closer together, or lock. If this is true, the smaller the scale (amount) the fast the drying to achieve a surface hardness and why a small piece of soap becomes harder faster. It seems there is a whole world of information about cold process soap in this small process of touching soap throughout the curing time.

Do you think the process is accelerated by size? Or is the process the process? Would it take longer to microwave an elephant or a mouse? Is the process the process? I know what I think, but I'd like to hear your thoughts.

 

[earlene]

Do you think the process is accelerated by size? Or is the process the process? Would it take longer to microwave an elephant or a mouse? Is the process the process? I know what I think, but I'd like to hear your thoughts.

I am one who believes the process is the process, but of course some factors, which could be termed 'variables' can and do affect the process. That of course is a generalization, but it is what I learned about processes.

Is size or mass a variable? I don't see why not.

 

[AliOop]

In relation to speed of evaporation, I absolutely believe size is a variable... but what about surface area + size?

This is just an assumption on my part, but I'd guess that a large, heavy but thin piece of soap would undergo faster evaporation than the same weight of soap that is shaped into a thick block form.

Example: think of a beach towel that is all balled up on the concrete by the side of the pool, as opposed to one that is spread out over a larger area. Which one will dry faster?

 

[SoapWitch]

In relation to speed of evaporation, I absolutely believe size is a variable... but what about surface area + size?

This is just an assumption on my part, but I'd guess that a large, heavy but thin piece of soap would undergo faster evaporation than the same weight of soap that is shaped into a thick block form.

Example: think of a beach towel that is all balled up on the concrete by the side of the pool, as opposed to one that is spread out over a larger area. Which one will dry faster?

This post reflects my thoughts as well... And then, I wonder, like earlene posted, is the process the process? For example, evaporation happens regardless of size. Does crystallization need to happen, or does happen, regardless of size? If that is the case at what point is it locked or has the structure formed i.e. hardened? Now that I wrote this, I realized the point of no return, whereas, with soap dough (and I would think this applies to bars of soap) there is a point of no return for making it pliable, and that is the point I see as "locking the structure". To have this understanding is not just for soap dough, but for stamping a soap, plaining, beveling etc. There is a window for those procedures.

 

[Kiti Williams]

I am part of a crafting forum on FB, I answer all soap questions to the best of what is said here. One person asked about Castile soap, how long to cure and the safe handling of the lye.

 

[AliOop]

This post reflects my thoughts as well... And then, I wonder, like earlene posted, is the process the process? For example, evaporation happens regardless of size. Does crystallization need to happen, or does happen, regardless of size? If that is the case at what point is it locked or has the structure formed i.e. hardened? Now that I wrote this, I realized the point of no return, whereas, with soap dough (and I would think this applies to bars of soap) there is a point of no return for making it pliable, and that is the point I see as "locking the structure". To have this understanding is not just for soap dough, but for stamping a soap, plaining, beveling etc. There is a window for those procedures.

My understanding is that crystallization is at least to some extent (how much is a good question) a by-product (for lack of a better word) of evaporation. So the faster the evaporation happens, that should also speed up crystallization, or "locking." Conversely, the evaporation process should slow down as the water content of the bar begins to equalize with the ambient temperature and humidity. This is what we see with soap dough left out, or soap batter left to cure after saponification, yes? But given that we can convert soap back into "neat" phase with heat, water, and time, is there truly a "point of no return"?

Additionally, I still am not convinced that evaporation and ambient temp/humidity are the only factors involved in the "locking." EX: I have some 2yo soaps that were "meh" at even 8 weeks of cure, but are now absolutely delightful. @earlene has some salt bars that were unbearable to her skin for years - but are now bearable after an extremely long cure.

It's hard to believe that the last small amounts of evaporation, causing presumably small amounts of additional "locking" over the last months/years, were the sole cause of these significant changes. Methinks there is more to it.

 

[SoapWitch]

My understanding is that crystallization is at least to some extent (how much is a good question) a by-product (for lack of a better word) of evaporation. So the faster the evaporation happens, that should also speed up crystallization, or "locking." Conversely, the evaporation process should slow down as the water content of the bar begins to equalize with the ambient temperature and humidity. This is what we see with soap dough left out, or soap batter left to cure after saponification, yes? But given that we can convert soap back into "neat" phase with heat, water, and time, is there truly a "point of no return"?

Additionally, I still am not convinced that evaporation and ambient temp/humidity are the only factors involved in the "locking." EX: I have some 2yo soaps that were "meh" at even 8 weeks of cure, but are now absolutely delightful. @earlene has some salt bars that were unbearable to her skin for years - but are now bearable after an extremely long cure.

It's hard to believe that the last small amounts of evaporation, causing presumably small amounts of additional "locking" over the last months/years, were the sole cause of these significant changes. Methinks there is more to it.

Aliop, you brought up a good point, and one that reflects my thinking as I read it, which is "at the point of no return". I wrote this in relation to soap that can or will no longer be pliable relating to soap dough and/or stamping soap, however, the part that I failed to see was that fully cured soap can be milled and reconstituted into another form of soap, and be even harder that time. Marseille soap aka mill soap is an example of this process. Need to go have a another think about this process.

 

[AliOop]

Funny, I was thinking of rebatch (returning to "neat phase") but didn't consider milling. Lots of different factors and possibilities.

 

[SoapWitch]

Funny, I was thinking of rebatch (returning to "neat phase") but didn't consider milling. Lots of different factors and possibilities.

Oh my gosh, I like how you think.

 

[Microchick]

I have seen the changes and it is very interesting. My granddaughter has looked at new fresh soap slices and old soap slices under her compound microscope and you can definitely see the crystalline structure change. Sadly, she did not get her camera connected to her computer after her previous computer crashed. I wanted her to send me the pictures so I could post the pictures here but I believe she forgot. Then life got in the way and we both forgot to pursue it.

That is so cool!

 

[Susie]

I am no longer a member of any FB soaping groups as they are always full of misinformation. And the more ridiculous the claim, the more they seem to support it.

 

[SoapWitch]

That is so cool!

Super interested, if you ever get the photos! This is exciting.

 

[cmzaha]

Aliop, you brought up a good point, and one that reflects my thinking as I read it, which is "at the point of no return". I wrote this in relation to soap that can or will no longer be pliable relating to soap dough and/or stamping soap, however, the part that I failed to see was that fully cured soap can be milled and reconstituted into another form of soap, and be even harder that time. Marseille soap aka mill soap is an example of this process. Need to go have a another think about this process.

We cannot mill handmade soap, we can only rebatch soap. Rebatch does not remove the water like true milling will do, in fact, you usually have to add in liquid to rebatch.

Milled soap was invented in the 18th century using a process of using soap, shredding it, and running the shredded soap through a pressing machine with rollers. Some even remove the glycerin before milling soap. By doing this they are creating a hard bar after removing all the water from the soap which also reduces curing time. Additives can be added each time the soap is run through the roller/pressing machine, which is usually 3 times, resulting in what we know as "Triple Milled" soap.

 

[DianaMoon]

I have seen the changes and it is very interesting. My granddaughter has looked at new fresh soap slices and old soap slices under her compound microscope and you can definitely see the crystalline structure change. Sadly, she did not get her camera connected to her computer after her previous computer crashed. I wanted her to send me the pictures so I could post the pictures here but I believe she forgot. Then life got in the way and we both forgot to pursue it.

Does it actually change or does it get tighter? (Change meaning alter the direction of the bonds to create a different shape.)

My understanding is that crystallization is at least to some extent (how much is a good question) a by-product (for lack of a better word) of evaporation. So the faster the evaporation happens, that should also speed up crystallization, or "locking." Conversely, the evaporation process should slow down as the water content of the bar begins to equalize with the ambient temperature and humidity. This is what we see with soap dough left out, or soap batter left to cure after saponification, yes? But given that we can convert soap back into "neat" phase with heat, water, and time, is there truly a "point of no return"?

Additionally, I still am not convinced that evaporation and ambient temp/humidity are the only factors involved in the "locking." EX: I have some 2yo soaps that were "meh" at even 8 weeks of cure, but are now absolutely delightful. @earlene has some salt bars that were unbearable to her skin for years - but are now bearable after an extremely long cure.

It's hard to believe that the last small amounts of evaporation, causing presumably small amounts of additional "locking" over the last months/years, were the sole cause of these significant changes. Methinks there is more to it.

I've been thinking of the evaporation process a lot recently. Briefly, those of us who measure things in grams on little kitchen scales have comparatively crude instruments. My soap stays the same amount of grams but I am 99% sure that there is a tiny amount of moisture that is evaporating, and which I can't measure with my little kitchen scale. It's a tiny amount but makes a big difference on the level of a crystal molecule.

Think of it like paper that desiccates over a period of time. There is some moisture in that paper which we can't measure - but it's there. Same with soap. This accounts for the hardening of soap after several months' cure.