White speckle/streak in soap

[Foggy]

So lately, my bars have been turning out white and speckle-y after a day's cure. I don't believe it is lye, I used the soaps myself to check. I always use the exact same recipe as well... palm, olive, castor, coconut. Some days it is good, others i get the gross whiteness you see in the pictures. As an experiment, I made a batch and used half of it as oven process and the other half as cold process. As you can see in the photo of the pink bars, the bar on the left is clear and looks great (CPOP) while the cold process bar is speckle-y. Could this be a temperature issue? or maybe excess stearic acid in my palm? I mixed my own palm before using but you never know if the supplier didn't mix it properly...
Couldn't find much info on this problem on the web. Help would be appreciated!
Thanks!

 

[shunt2011]

To me they look like they may have overheated a bit causing stearic spots or glycerine. And some look like maybe they have a bit of ash. Hard to tell for sure.

 

[Susie]

I see ash on some, and stearic spots in others. Best way to know for sure if it is stearic spots is to substitute out lard or tallow for the palm and see what you get. Ash is easier to remove than prevent.

 

[The Efficacious Gentleman]

Hi to you, too!

Just to clarify, did you do two CPs, one of which was CPOP? Or was one an oven HP?

Did you change suppliers or size of oil container purchased? Or did your supplier change supplier?

 

[topofmurrayhill]

I know that people associate this with palm oil, but it still goes unexplained. What is a "stearic spot" and why would there be one? Palm doesn't have much stearic, but tallow does so why is tallow the one that doesn't do this? You can say it's actually "palmitic spots" but lard had just as much as palmitic and doesn't do this.

So the whole thing still begs a proper explanation.

 

[cmzaha]

I know that people associate this with palm oil, but it still goes unexplained. What is a "stearic spot" and why would there be one? Palm doesn't have much stearic, but tallow does so why is tallow the one that doesn't do this? You can say it's actually "palmitic spots" but lard had just as much as palmitic and doesn't do this.

So the whole thing still begs a proper explanation.

I have often wondered the same thing.

 

[The Efficacious Gentleman]

Is it that, in palm oil, the stearic, although a smaller amount, melts at a higher temperature than the palmic and so tends to clump when the whole pot of palm oil melts and solidifies unevenly, leading to an uneven distribution of fatty acids in the tub and therefore also in the soap? Compounded then, by uneven hardening in the mould itself?

Tallow, having more stearic, doesn't have the same issue of uneven distribution, being more uniformly stearic even when melted?

 

[topofmurrayhill]

Is it that, in palm oil, the stearic, although a smaller amount, melts at a higher temperature than the palmic and so tends to clump when the whole pot of palm oil melts and solidifies unevenly, leading to an uneven distribution of fatty acids in the tub and therefore also in the soap? Compounded then, by uneven hardening in the mould itself?

Tallow, having more stearic, doesn't have the same issue of uneven distribution, being more uniformly stearic even when melted?

Some reasonable speculations, Craig.

I suspect we can take a chance and eliminate literal "stearic" from the discussion. It's probably a misnomer.

There is commonly confusion between stearic, the fatty acid, and stearin, a term for the solid fraction of a fat. It's named after stearic, but in the case of palm oil it comes mainly from the palmitic acid content. Same for cool or cold olive oil. So "stearin spots" is probably the intended meaning.

Temperature is sometimes implicated. Some people report the problem is resolved soaping warmer and some don't. After you melt all your oils together, the combination is homogeneous. With enough hard oils, the mixture can start to crystallize as it cools. It usually stays pretty homogeneous, beginning with some cloudiness and possibly advancing to a creamy and maybe a slightly grainy state.

Clumping doesn't seem to happen with oils alone, but maybe it's possible in the presence of lye. It sounds plausible, but still begs the question of what's so special about palm oil. Tallow and lard and tropical butters all have ample amounts of stearic and/or palmitic in their fatty acid profiles. Your recipe can have a similar fatty acid profile whether you use those fats or palm oil, but only palm is implicated.

It might be interesting if we could obtain some palm stearin (not palm stearic -- totally different thing) to soap with and see if using it exacerbates the problem.

 

[topofmurrayhill]

Two more quick thoughts.

I realized I do have palm stearin. Kind of. For the hell of it, I did an amateur fractionation of some palm oil one winter when it was very cold. I don't know how efficiently I did it, but I have some plastic tubs of quite solid palm oil.

Also, if it's correct that palm oil is responsible for the spots and the spots are some kind of palm stearin, the special thing about palm might not be the fatty acid composition so much as the triglyceride composition compared to tropical butters or animal fats.

Fatty acids occur not only in certain amounts, but in certain combinations because they are grouped into threes. The way fatty acids are distributed among the different positions of the triglycerides can be another unique signature of a particular oil.

For instance, imagine an oil that's one third palmitic and two thirds oleic in its fatty acid profile. Now imagine two extremes. One third of the oil could be tri-palmitin and two thirds tri-olein, where all the triglycerides are comprised of just one type of fatty acid. Or all of the triglycerides could contain two oleic and one palmitic.