Is there any benefit on using liquid glycerin in your batch?

[SunRiseArts]

I ask, because lately I was looking at recipes online, and some have glycerin added to it. I thought it was odd.

 

[SaltedFig]

Glycerin is a byproduct of the soap making process, as you know (triglycerides in the oils we use to make soap are 3 parts fatty acids to 1 part glycerin).

When a fatty acid is added directly to a recipe (as stearic acid sometimes is, especially for shaving soaps), glycerin is added back in the same ratio (3 parts stearic to 1 part glycerin).

Sometimes glycerin can be used to mix colours, so it would be listed as a separate ingredient.

Other than for those two purposes, it could be added in a small amount to soften a hard soap or to attract a bit of extra water, but it wouldn't take much to make the soap too soft (hand-made soap already has a lot of glycerin).

Commercial soaps have glycerin as an ingredient because the fats have been broken down into the individual fatty acids and recombined to a precise recipe, so the glycerin needs to be added back in (in the same way we do when we make a shave soap) and listed as an ingredient.

 

[earlene]

Yes, too much added glycerin, even when used to mix colorants, can make a very spongy soap that may never get hard. I am still waiting for the bars of this soap to harden up:



I made it 19 months ago and it looks and feels the same today as it did when I first cut it. I have re-batched some of it, but am keeping some to see if it ever changes.

The colors weren't even that well mixed, either, as you can see from the TD smears and the solid mica spots of one of the darker colors. ETA: Of course that was the fault of the user (me), not the glycerin.

 

[cmzaha]

I do mix most of my colors with glycerin, but they have to be mixed quite thick so no to much glycerin is added back in. My main recipes are very hard to begin with so they do accept the amount of glycerin I mix my colors with. It is true that to much will make a spongy soap and it is used as one of the solvents when making melt and pour. So to answer your question there is no advantage to adding in glycerin only a disadvantage if to much is used.

 

[SunRiseArts]

Interesting, thank you all. It did not occur to me when I was reading the ingredients that it may have been listed because of the color. Makes me think sometimes I have use the color that comes in glycerin instead of mica, and never listed the glycerin!

I was just looking at pretty things on etsy.

 

[PatrickH]

Here's a soap from a local soap makers business that has Glycerin added on the list of ingredients, so I'm assuming it's extra added in.
Doesn't do any good at all for my winter hands and it looks weird as shown in the pictures.
I thought about adding extra until I tried this soap.

 

[lsg]

I use a little liquid in my mechanics soap to offset the scratchiness of the pumice. Adding too much glycerine to soap will result in a sticky bar.

 

[BattleGnome]

Doesn't do any good at all for my winter hands and it looks weird as shown in the pictures.

Looks like glycerin dew. Harmless but it’s the reason we wrap m&p until use. I forgot who did it, but someone has a story about patch testing glycerin while living in the desert/super arid location. There wasn’t enough moisture in the air for the glycerin so it pulled moisture from her skin (not bad, just enough to prove glycerin’s humectant properties).

 

[SunRiseArts]

Thank you both. Interesting. I am always learning new things!