Vomit smell but no milk used

[Bee55]

Hello

I’m new to this forum and would appreciate your input. Last few batches have an acid vomitty smell to them when they lather. Otherwise the smell is fine, it’s only when they lather they leave a vomitty smell on the skin. Very odd.
The oils used are quite basic, the only thing i could think of that can cause this is unrefined Shea butter? But when I tried to test this using a huge amount - 50% Shea butter/ olive oil soap it didn’t have the smell.

Other oils in the recipe are olive, coconut, palm, castor. As you can see quite standard and nothing in high risk of being rancid.

 

[szaza]

Hello Bee55, welcome to the forum!
About your question.. did you add anything else to your soap except oils, distilled water and lye? (Color/scent/other additives..). You say it's only the last few batches, is there anything that changed in your recipe or method?

 

[Bee55]

Hi! No, I didn’t add anything was totally plain. I did use tap water though, but I always used it for years now and never had an issue. I did use more shea butter than usual, around 15%. That’s the only difference.

 

[lsg]

Are any of your oils old? (Past the shelf life) I have used unrefined shea butter, but I have never noticed any off smell. I always add either FO or EOs to my soap. Maybe that covered up the odor.

 

[Bee55]

All were fresh besides the palm oil which may have been older, I smelled it and it doesn’t smell rancid though. Hence my confusion.

 

[szaza]

Interesting! Some minerals in tab water can increase the chance of rancidity. Is there a possibility your tab water was harder than normal for a while? Though rancidity usually also shows up on the bar as orange spots or discoloration.
I've only used refined shea up to now, so I don't know if unrefined shea might play a role. Though I'd expect your 50% shea soap to be stinky if it did.
Maybe try a soap high in palm and see if that's the culprit? (Though generally oils are fine if they smell ok). How was trace? If one of your oils is old trace can speed up.

 

[Bee55]

Oh yes I live in a very hard water area, although the soap is white as snow, no spots. Trace was usual, a few mins with a stick blended nothing out of the ordinary. There’s always a chance the palm was on the verge of rancidity and went bad in the soap? I don’t have anymore of the palm to do a test unfortunately.. I suppose it’s just one of those things. I can recognise a rancid smell but I never encountered rancidity that smells like vomit, would you think it’s possible?

 

[szaza]

There’s always a chance the palm was on the verge of rancidity and went bad in the soap?

possible, not sure if it's likely.. in that case the problem should stop once you start using a new bucket of palm oil.

I never encountered rancidity that smells like vomit

Me neither.. rancidity is the most likely cause of bad smelling soap, but I don't think I've ever described it as vomit-like either.
If you're in a hard water area I'd recommend using distilled water, just as a precaution (it's sold rediculously cheap at the supermarket for steam irons, so look in the laundry section). Some unwanted advise: Dissolving citric acid in your water before adding the lye (CA at 2% of oil weight and extra NaOH added, for how to calculate is explained here) really helps to prevent soap scum.

 

[Bee55]

Thank you all for the input, I’ll try a batch with new palm oil hopefully it doesn’t repeat. I’ve not heard about the citric acid tip before, very interesting! Thank you

 

[szaza]

Let us know how it goes! I'm curious if it's indeed the palm or something else entirely.

 

[Noreen Moore]

I have citric acid. I want to up my skill set with additives. Especially citric acid.
Well! How did I graduate from college? My math ability is abysmal! Yet I figured out how to calculate volume of oils for molds. I am a little nervous about this one because it's extra lye.
(had my first major WHOOPS drop splatter raining down light trace hot soap accident yesterday in the middle of pour and have 4 little tiny burns as it got into my right glove! Going to secure cuff of glove now with a rubber band!) And we have respect for the lye!

 

[cmzaha]

The odor is strange because I have used very old palm oil with no off odor. But soap does have a habit of doing what it wants to do.

I have citric acid. I want to up my skill set with additives. Especially citric acid.
Well! How did I graduate from college? My math ability is abysmal! Yet I figured out how to calculate volume of oils for molds. I am a little nervous about this one because it's extra lye.

Just multiply the quantity of citric acid you are going to use by 0.624 to give you the extra amount of lye needed. Why are you nervous about the little extra bit of lye? When I used Citric Acid as a chelator I figured 2% of my total batch weight. I now use Tetrasodium EDTA and Sodium Gluconate.

If you were making a 32 oz batch of soap (907g) and wanted to use 2% CA it would be 18 g of CA which would require 11 g extra NaOH. (I round down to even grams)

 

[omniverse99]

The odor is strange because I have used very old palm oil with no off odor. But soap does have a habit of doing what it wants to do.

Just multiply the quantity of citric acid you are going to use by 0.624 to give you the extra amount of lye needed. Why are you nervous about the little extra bit of lye? When I used Citric Acid as a chelator I figured 2% of my total batch weight. I now use Tetrasodium EDTA and Sodium Gluconate.

If you were making a 32 oz batch of soap (907g) and wanted to use 2% CA it would be 18 g of CA which would require 11 g extra NaOH. (I round down to even grams)

Hello so you use 2 chealators together? Why and how doften they preform together? At what percentage of both, and do you feel like it dries out the skin?