I was going to pose the questions and musings below in this thread, but then it started to feel like a hijack, so I decided to start a new thread.
@DeeAnna - I appreciate the very succinct, clear answer you gave about the effects of castor and sugar in post #11 of the other thread. This “oh, to be a chemist” soap maker has a few more how/why type questions for you when/if you have time.
The ricinoleic acid supplied by castor oil DOES increase the solubility of the soap somewhat... The other aspect of using castor is that it adds stability to the lather created by the other fatty acids in the soap. If the lather lasts longer, there's more lather to enjoy for a longer time.
Is the solubility effect due mostly to the bulkiness of the molecule, and is that because the bulkiness causes disruption of the crystalline structure? (you partially answered this question later in the post). I think I’ve read something, possibly in Dunn’s book, about the kinky olive oil molecule not lining up neatly in the soap matrix. I also remember from some of your earlier posts that the K in KOH is bigger than the Na in NaOH. According to Wikipedia, the hydroxyl functional group makes castor oil a bit more polar than the other fatty acids. Would that also help with solubility by changing the way the soap interacts with the water? I’m struggling a bit here, but I think I’m asking if the hydroxyl group makes it chemically easier for the soap to dissolve (as opposed to the effect on the crystalline structure that makes it easier for water to get in and around the soap molecules).
Sugar and other lather-boosting additives act in a similar way [to castor oil] -- they increase the solubility of a soap by interfering with the crystalline structure of the soap.
Articles I’ve read about making bubbles and bubble blowing liquid solutions mention that adding corn syrup or glycerin to homemade detergent-based bubble-blowing mixes makes the bubbles last longer. Apparently it works because the additives decrease the surface tension of the water and also because they slow down evaporation of the water. So then, in addition to effects on crystalline structure, can we assume that any dissolved/or dissolving sugar from a bar of soap in use has the same effects on surface tension and evaporation? Sorbitol is bulkier than sugar, I think, and if that bulkiness is retained in the presence of NaOH, maybe it’s an explanation for why it boosts bubbles a bit more than table sugar? It’s also a sugar alcohol. Does that mean it also serves as a polar solvent? (should I already know the answer? Something in my brain is telling me that I should be reading about making transparent CP and melt & pour. )
I’m still very much on the learning curve when it comes to understanding what might be happening with most of the other additives, especially the starches. So far I’ve read that the addition of NaOH to starch mixtures can change the structure of the starch, cause swelling/gelling, break the molecules down to peptides and sugars, and a lot more details that I haven’t been able to consolidate in my brain. For simplicity, I want to assume that any sugars that result from the breakdown of starches, will behave like added sugars. That still leaves a lot of potential for unusual things to be happening in the batter bowl.
This article (and linked articles) about what might be happening on the outside of starchy pretzel dough after it’s dipped in lye offers some clues and is a fun read.
@DeeAnna - I appreciate the very succinct, clear answer you gave about the effects of castor and sugar in post #11 of the other thread. This “oh, to be a chemist” soap maker has a few more how/why type questions for you when/if you have time.
The ricinoleic acid supplied by castor oil DOES increase the solubility of the soap somewhat... The other aspect of using castor is that it adds stability to the lather created by the other fatty acids in the soap. If the lather lasts longer, there's more lather to enjoy for a longer time.
Is the solubility effect due mostly to the bulkiness of the molecule, and is that because the bulkiness causes disruption of the crystalline structure? (you partially answered this question later in the post). I think I’ve read something, possibly in Dunn’s book, about the kinky olive oil molecule not lining up neatly in the soap matrix. I also remember from some of your earlier posts that the K in KOH is bigger than the Na in NaOH. According to Wikipedia, the hydroxyl functional group makes castor oil a bit more polar than the other fatty acids. Would that also help with solubility by changing the way the soap interacts with the water? I’m struggling a bit here, but I think I’m asking if the hydroxyl group makes it chemically easier for the soap to dissolve (as opposed to the effect on the crystalline structure that makes it easier for water to get in and around the soap molecules).
Sugar and other lather-boosting additives act in a similar way [to castor oil] -- they increase the solubility of a soap by interfering with the crystalline structure of the soap.
Articles I’ve read about making bubbles and bubble blowing liquid solutions mention that adding corn syrup or glycerin to homemade detergent-based bubble-blowing mixes makes the bubbles last longer. Apparently it works because the additives decrease the surface tension of the water and also because they slow down evaporation of the water. So then, in addition to effects on crystalline structure, can we assume that any dissolved/or dissolving sugar from a bar of soap in use has the same effects on surface tension and evaporation? Sorbitol is bulkier than sugar, I think, and if that bulkiness is retained in the presence of NaOH, maybe it’s an explanation for why it boosts bubbles a bit more than table sugar? It’s also a sugar alcohol. Does that mean it also serves as a polar solvent? (should I already know the answer? Something in my brain is telling me that I should be reading about making transparent CP and melt & pour. )
I’m still very much on the learning curve when it comes to understanding what might be happening with most of the other additives, especially the starches. So far I’ve read that the addition of NaOH to starch mixtures can change the structure of the starch, cause swelling/gelling, break the molecules down to peptides and sugars, and a lot more details that I haven’t been able to consolidate in my brain. For simplicity, I want to assume that any sugars that result from the breakdown of starches, will behave like added sugars. That still leaves a lot of potential for unusual things to be happening in the batter bowl.
This article (and linked articles) about what might be happening on the outside of starchy pretzel dough after it’s dipped in lye offers some clues and is a fun read.
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