Cold process melt & pour soap base from scratch... Is it possible?

[Fsm_Soap]

I've recently been reading about making melt & pour soap from scratch. While I understand the purpose of some of the additives used I still don't quite understand why melt & pour cannot be made via the cold process method. Every recipe I've looked at requires hot processing the soap. What is it in the hot process method that contributes to the 'meltability' of the soap? I'm not very concerned with making a hard or transparent base. If it's on the softer side and opaque that would totally be fine as long as it is meltable. Can anyone shed some light on this and whether it's actually possible to make a cold process melt & pour soap base?

 

[DeeAnna]

You have to get the solvents intimately incorporated into the structure of the finished soap and this requires heating and mixing and some time. The solvents interfere with the normal crystalline structure of the soap, so we're talking about mixing on a molecular level. This is the key to what makes the soap a transparent type (which includes melt and pour).

You can't get this job done properly with a cold process method -- the solvents would have to be added to the soap batter before the soap is actually soap. You can't add solvents to finished soap at room temperature and end up with a transparent soap either. Heat and mixing and time are required.

 

[Fsm_Soap]

Ah I see.. That makes so much sense. Thank you so much for the detailed explanation! Based on that, can I assume that the solvents can be added to rebatched CP soap to achieve some type of melt & pour?

 

[DeeAnna]

Yes you can "rebatch" finished soap by adding solvents and end up with a transparent type soap. I can't provide details -- I've never done this.

I'm not informed enough on the specific solvents required to make M&P type soap rather than generic transparent soap. The only thing I do know you can't use alcohol to make M&P because reheating will simply evaporate the alcohol and the soap will return to its normal character.

 

[Fsm_Soap]

Thank you! That is really helpful. Now that I understand it all better I can do a bit more research and then get to experimenting!

 

[KimW]

This video might be of interest. It's now my preferred method for making my M&P base.

 

[Rosevalleysoaper]

How to Make Melt & Pour Soap Base from Scratch: A Beginner's Guide to Melt & Pour Soap Base Manufacturing https://www.amazon.com/dp/B009CD659G/ref=cm_sw_r_cp_apa_6744FbMWF1E0C

 

[Fsm_Soap]

@KimW & @Rosevalleysoaper, thank you! I will definitely check out the link & the book.

 

[TashaBird]

How are these clear soaps to use? How do they feel?

 

[Rosevalleysoaper]

https://www.soapmakingforum.com/threads/made-some-transparent-mp-from-scratch.58737/Here is one users thread on their use of one of the recipes from the book. I bought the book and thought to try the process but life happened. I wish you the best on your soap making journey! If you do try, it would be lovely to hear about your process and results!

 

[KimW]

How are these clear soaps to use? How do they feel?

I like them. I've never used purchased M&P, so with that I can't compare. Keeping in mind a soap's feel is subjective and based on the skin of the beholder, to me they feel as I'd expect a regular soap to feel based on the oils used. I.e. 100% coconut oil tends to leave my skin feeling tight, etc. With the exception of these bars being noticeably soft, if I were to wash my hands with my M&P with eyes closed I'd be hard pressed to know I was using a M&P bar vs a regular bar If any of that makes sense....LOL

 

[ResolvableOwl]

I still don't quite understand why melt & pour cannot be made via the cold process method. Every recipe I've looked at requires hot processing the soap. What is it in the hot process method that contributes to the 'meltability' of the soap?

IMHO nothing, except for some laziness due to the shorter processing time (hours instead of weeks) – and something about fatty acids (see below). I've made M&P base with good success from cold-process soap (though I'm with KimW in that I have no comparison with industrial M&P base):

I finely grate the soap, mixed it with the solvents (polyols, sugar, water), let it stand for a few days (solvents diffuse into the soap), and then gently warm up in a water bath until dissolved/molten. The point of the “soaking” is that you don't need to fully heat it up nearly to a boil (as you would with HP), but the plasticising properties of the polyols will jump in at much lower temperatures, and help fluidise the batter. Replacing heat by time.


Mixing the solvents into the lye at the very beginning of CP might sound tempting (keep in mind DeeAnna's “molecular level mixing” argument!). But the polyols dilute the lye (= slower saponification rate), and (more severely) they liquefy/dissolve trace (we want this, but not that early!), so that the batter will notoriously separate into lye+polyols and an oil layer. Source: own experiment (I nearly lost patience after three days of repeated blending and re-heating a pure palm M&P, and the result was impressively mediocre in the end).


Well, one thing that certainly prefers HP for M&P soap is the fatty acids. You'll notice that M&P recipes are generally very high in saturated fats, and many have pure fatty acid in them (stearic, palmitic). These are needed to get the bar hard at room temperature, instead of sticky/gel-like. But it also means that you'll have to heat the oils considerably to melt everything up (stearic acid Mp 69.3°C). And from there, it's only a small step to a full HP protocol.

 

[Fsm_Soap]

IMHO nothing, except for some laziness due to the shorter processing time (hours instead of weeks) – and something about fatty acids (see below). I've made M&P base with good success from cold-process soap (though I'm with KimW in that I have no comparison with industrial M&P base):

I finely grate the soap, mixed it with the solvents (polyols, sugar, water), let it stand for a few days (solvents diffuse into the soap), and then gently warm up in a water bath until dissolved/molten. The point of the “soaking” is that you don't need to fully heat it up nearly to a boil (as you would with HP), but the plasticising properties of the polyols will jump in at much lower temperatures, and help fluidise the batter. Replacing heat by time.


Mixing the solvents into the lye at the very beginning of CP might sound tempting (keep in mind DeeAnna's “molecular level mixing” argument!). But the polyols dilute the lye (= slower saponification rate), and (more severely) they liquefy/dissolve trace (we want this, but not that early!), so that the batter will notoriously separate into lye+polyols and an oil layer. Source: own experiment (I nearly lost patience after three days of repeated blending and re-heating a pure palm M&P, and the result was impressively mediocre in the end).


Well, one thing that certainly prefers HP for M&P soap is the fatty acids. You'll notice that M&P recipes are generally very high in saturated fats, and many have pure fatty acid in them (stearic, palmitic). These are needed to get the bar hard at room temperature, instead of sticky/gel-like. But it also means that you'll have to heat the oils considerably to melt everything up (stearic acid Mp 69.3°C). And from there, it's only a small step to a full HP protocol.

Thanks @ResolvableOwl for your detailed explanation! I'm so sorry, I actually somehow missed it. It's been a crazy year and I only just decided to come back to attempting melt and pour again so I revisited this thread. I just wanted to experiment so tried your technique with only glycerin as the solvent. Will outline it here for anyone interested.

1. Grated up some of my pure coconut oil cold process soap
2. Added around 30% of its weight in glycerin
3. Left it to soak overnight
4. Next day, heated it up over a double boiler with a splash of water and once melted, poured it into a square mold
5. Let it cool, unmolded it, cut it up and remelted to pour into flower molds (see picture)

Overall they turned out pretty great for a first attempt!

A few observations:
-The final soap melted down well but was solidifying quickly (even mid-pour) so there was a fair bit of soap I couldn't actually pour out
-It was foaming & bubbling while melting in the microwave
-I made a tiny quantity (around 50g total) so it was a bit fiddly to handle
-The only solvent I used was glycerin at 30% so my soaps were opaque

Pretty sure most of the above can be resolved with the correct & correct amount of solvents and maybe a larger batch of soap.

I'm so excited! Can't wait to experiment more with this technique!

 

[ResolvableOwl]

Nice! They have a great “shine” to them.

I'm honestly impressed that these 30% glycerol were sufficient for a successful melt! Usually a solvent amount in the ballpark of 100% of the soap weight is needed to get a somewhat transparent soap base that is free-flowing when melted. But then, I never tried it with 100% coconut (i. e. no long-chain oils); soaps that gave me reliable M&P, had at least 40% palmitic/stearic content.

Was your coconut soap superfatted? That's another point to keep in mind. Coconut soap won't become less harsh when diluted with a bit of glycerol. And high superfatting (that is reported to help for a less irritant soap) likely makes a very opaque, milky M&P base.

 

[Fsm_Soap]

To be honest, even I was surprised. My last experiment (prior to starting this thread) ended up in a gloopy glycerin mess so I figured my next attempt should be in baby steps.

Oops forgot to mention the superfat. Yes the coconut bars are 20% superfatted. I love them for personal use so always have a stock on hand. As you say though the M&P soaps do look milky. I'm not too concerned about transparency though, more about the meltability. That said, I would like to get my hands on some stearic acid, propylene glycol & sorbitol so I can give this another whirl.

 

[SavonP]

Soap and Clay on YouTube has a recent video on how to make melt and pour base. She says it’s relatively simply.

 

[ResolvableOwl]

@Fsm_Soap
These days, propylene glycol (vaper's supply?) and sorbitol (diabetic sweetener) are likely not too difficult to get hold of.
From a CP soapmaker's perspective: try anything to stay away from stearic acid (FFA)! This is the actual reason why most M&P recipes are HP: free stearic acid is peak annoying to work with, due to its high melting point (false trace) and instant seizing/soap-on-a-stick properties. It's a pain to work with, even in HP.

It is SO MUCH easier to work with chemically bound (triglyceride) stearic acid, like abundant in soy wax/hydrogenated vegetable oil, cocoa/shea/sal/kokum butter, palm stearin (“palm wax”), or various types of tallow.

 

[Fsm_Soap]

@ResolvableOwl Thanks for the tip about stearic acid! Will keep that in mind should I decide to try it.
Might be a good learning experience though. True, the other solvents shouldn't be difficult to get hold of... Looking forward to giving this another go!

@SavonP thank you, will check out that link!