Does Sugar Really Increase Bubbles?

[Saponista]

I think this is a question for DeeAnna. I know lots of people add sugar to their soap in order to increase bubbles. I am wondering whether there is a scientific explanation behind this? I hope someone can enlighten me please.

 

[lsg]

Here is what I found:

http://www.mfc.co.jp/english/whatsse.htm

Apparently sugar (sucrose) is a fatty acid ester.( This is wrong)

eta: I read the article wrong.

 

[Saponista]

Thanks Isg, that's really helpful.

 

[Seawolfe]

It really does help increase lather - hubby is my blind tester (he doesn't know hes a guinea pig), and without fail he notices the bars with sugar in them as lathering more. I've often wondered why it helps - sugar becomes a non-ionic surfactant! Something to bring up at the next cocktail party...

 

[squeakycleanuk]

How interesting, I hadn't heard of this before. Think I'm going to have to try it myself now How much sugar would you add?

 

[MorpheusPA]

Except those are sugar esters, not sugar itself--which is simple sucrose. I'm not sure if sugar would undergo esterization in saponification. Maybe.

 

[Obsidian]

I can't find the web site now but I read about how sugar makes the bubbles tougher and slows the rate of evaporation so bubbles last longer.

 

[KristaY]

Click on this link to see her lather results using sugar, sodium lactate, different superfat levels, clay, etc. Very enlightening!

https://www.flickr.com/photos/amathiasoapworks/7024620865/in/album-72157629324839760/

 

[DeeAnna]

Soap likes to form a crystalline structure and that strong framework gives a bar soap its usual firmness.

Sugar interferes with the crystalline structure of soap. If you use enough sugar, you can disrupt the crystalline structure enough that the soap becomes semi-transparent. Add too much sugar, however, and the soap will become soft and pliable, even sticky.

Anyways, a material that is crystalline is tougher -- more resistant to being worn away -- than the same material that isn't in a crystalline form. Soap with sugar is less crystalline, so it is not as abrasion resistant, so it wears away faster, so you get more soap on your hands for the same amount of work, and <pant, pant!> so the end result is more lather.

 

[DeeAnna]

If you read Auntie Clara's article here: http://auntieclaras.com/2014/05/glycerine-rivers-trying-to-understand-them/ and go down toward the middle of the page, you can see some of Clara's nice photos of what soap really looks like inside when it's allowed to break apart along its natural crystalline structure.

 

[Dorymae]

DeeAnna, in that article she says that ungelled soap is not crystallized. Does that mean ungelled soap would be a slight bit softer and therefore you would get more soap and more bubbles using it?

 

[Saponista]

Thank you DeeAnna for your great explanation and links and everyone else for all their useful links too. I shall go away and have a good read. This is so interesting, I love learning about the chemistry behind things.

 

[DeeAnna]

Dorymae -- If I'm following you correctly, I think the article might imply that soap that gels does crystallize and soap that doesn't gel does not crystallize. If so, I don't think that's what Clara meant, although I can see why people might pick up on that incorrectly. Soap crystallizes, meaning it creates some kind of orderly structure, whether it gels or doesn't gel. The kind of crystalline structure might be different for gelled soaps vs. not-gelled soaps, but there's a crystalline structure.

Here's an analogy: One end of each soap molecule is positively charged (the sodium Na end) and the other fatty-acid end is negatively charged. Think of each molecule as a kind of magnet. Magnets really desperately want to align themselves so the north pole of a magnet is near the south pole of another. Soap molecules are a bit like magnets -- the sodium end of one soap molecule wants to be next to the fatty acid end of another soap molecule so the electrical charges are evened out.

Since there are a bazillion soap molecules all seeking the same kind of electrical nirvana, they solve this problem by organizing themselves into a variety of interesting shapes -- sheets, balls, cylinders -- that allow the sodium ends to face toward the fatty acid ends, rather than be all jumbled about in a random mess. This orderliness is the crystalline structure I'm talking about. Gel might make all these soapy gymnastics easier, but even without gel, the soap molecules are going to create some kind of orderly structure that makes them "happy". It might take longer, but they will figure it out eventually.

The physical hardness of a soap is more determined by the amount of water used to make the soap, all other things being equal. According to a study done by Kevin Dunn, higher water soap is softer at the time of unmolding than lower water soap. As the soap cures, the higher water soaps will become about as hard as the lower water soaps, so the difference between the soaps gradually evaporates (pun intended) with time.

 

[Dorymae]

Ah I see,so then there should not be any discernible difference in bubbles between the two. Good to know. Thank you for taking the time to explain that.

 

[DeeAnna]

Dorymae: Short answer -- nope, I really don't think so. I get long winded sometimes.

 

[Luv2Soap]

I added sugar to my distilled water and made sure it was fully dissolved before I added my lye. The water has a slight yellow tinge to it which is different than I'm normally used to seeing. Normally my water ends up being crystal clear when the lye dissolves.

Is this lye water still okay to use?

 

[Seawolfe]

Mine always has a yellow tinge, but my sugar isn't white white, it's un bleached or something?

 

[lionprincess00]

I added sugar to my distilled water and made sure it was fully dissolved before I added my lye. The water has a slight yellow tinge to it which is different than I'm normally used to seeing. Normally my water ends up being crystal clear when the lye dissolves.

Is this lye water still okay to use?

The higher lye concentration, the more Amber the water becomes when adding sugar.
I add sugar and sodium citrate to my water. Heat til dissolved making sure not to bubble up. Then remove, cool, add lye. It turns Amber yellow.
It is fine to use, I do, and it doesn't affect final color.

I use 40% lye concentration which is 1.5:1 ratio, far from full water, and that's usually a contributing factor. When I use full water the sugar rarely affects the color, but the high lye concentration with the sugar and sodium citrate manages to really heat things up, thus the yellow Amber color from heated sugars.

 

[djk17]

I make a simple sugar syrup and add it at trace. I reduce the distilled water accordingly.
I've always done 1 Tbsp ppo--am curious now how much others add?

 

[MorpheusPA]

I make a simple sugar syrup and add it at trace. I reduce the distilled water accordingly.
I've always done 1 Tbsp ppo--am curious now how much others add?

1 tsp PPO, but 1 Tbsp is just fine. I generally add my sugar to the oils and let it dissolve as the lye water gets stirred around. So far, that's worked perfectly, and no discoloration at all that I can see.

I do the same with honey, and no matter what you do to that, it discolors when hit by lye. Fortunately, that fades. I had a pumpkin orange batter (uncolored except by honey) fade to pure white in about a week.