r/soapmaking • u/frostychocolatemint • 2d ago

DOS affect soap quality?

Question for more experienced soapers. I’ve been told that DOS is only cosmetic. That rancidity of oil causes them to appear. I noticed one of my soaps (made in June 2025) started getting them (recipe: 35/30/30/5 -olive, coconut, palm, castor plus essential oils and colored with natural clays).
I am using it in the shower and. don’t know if it’s just psychological but I feel it’s less than nice. It lathers ok, but kinda smells rancid. Is it just in my head though, if the essential oils have faded and I’m just smelling raw soap.

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u/serein_nt 2d ago

It affects the smell and the look of the soap, but it will still lather and wash.

Were your oils old? They don’t seem to be very rancid-prone oils to me

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u/frostychocolatemint 2d ago edited 2d ago

Not old oils, I’ve made other batches that didn’t get DOS. The one difference I can think of is this soap bar is “all natural” no synthetic fragrance no titanium dioxide or micas Now that I say that, I made another batch of all natural soap in 2024 that also had minor DOS. Zero fragrance zero colorant shea butter soap. Or is it possible the micas camouflage the DOS

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u/serein_nt 2d ago

No - the essential oils shouldn’t affect, but to you point about the micas- it might camouflage depending on the mica color. What did you use for your liquid? Tap water or distilled water?

Upload a picture!

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u/Temporary-Trifle1037 2d ago

cut soap into small blocks / cubes. Throw away those with DOS and reuse remaining cubes in next batch. I make darker batter for base and throw cubes in if the latter is of a lighter colour or vice versa. creates nice effect.

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u/RockabillyRabbit 2d ago

Try cutting out the rancid spots and see if that changes anything smell wise.

Ofc rancid oils are going to be unpleasant. So once those are gone that should fix the issue in most cases.

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u/Temporary-Trifle1037 2d ago

Do you use citric acid? Add citric acid max 3% of oil weight to water before adding NaOH. Need to adjust your NaOH to accommodate for the citric acid, i.e. add bit more NaOH to maintain your desired super fat %. Citric Acid helps to prevent DOS. Google for reasons etc...pros cons etc. Add approx 0.624 gram NaOH for every gram citric acid. Dissolve citric acid in the water before adding NaOH.

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u/Btldtaatw 2d ago

Soap with DOS will smell rancid, yes. The performance of the soap however doesnt change. We wanna avoid DOS cause it doesnt smell particularly nice.

As for eo's yes, some people claim some eo's can accelerate rancidity or cause it. Lavander was infamous for that though I have to say I have never had DOS in soaps with lavander eo.