(Cold Process) Soap smells rancid when used but smelled fine before use

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Natchanon

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Hello all,

I'm new to soap making and looking for advice. About 3 weeks ago, I made two batches of cold process soaps and added fragrance oil as scents.
Today, I tried it and was kind of disappointed. While it washed well like a regular soap with pretty good lather, it smelled different.
Before I used it, it smelled pretty good. The fragrance oils (coffee and deep forest) I added have developed and mellowed out a bit. But when I used it, it smelled rancid with only a very faint trace of the fragrance. It smelled rather like oil, and the rancid smell was left on the soap as well after using it. Could anyone tell me what could cause this? I attached my recipe here in case there is something anyone can point out or suggest some adjustments.

Note: I didn't use the the hard coconut oil that you have to melt. I used the coconut cooking oil that's always liquid. It's not yellow; that's the color of the bottle. But I can tell that it tastes and smells less pleasant than the hard oil counterpart. The very yellow oil is the rice bran oil I used. Every oil except the shea butter and olive pomace are cooking oils you find at a supermarket.

Note 2: I left them to cure out on the porch for a week or two before I wised up and realized I should've moved them inside to avoid sunlight.

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Thanks!
 
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Since you used liquid coconut oil, you should have not have selected Coconut Oil, 76 degree, because that is the solid coconut oil. You should have selected Coconut Oil, Fractionated in SoapCalc.

As to the smell, my best guess is that they are becoming rancid due to exposure to sunlight. Some of your oils may also have been old; supermarket oils frequently are. Rebatching doesn't help rancidity, so you can either toss these bars, or salt them out. There are some good posts on this forum that will teach you how to salt out the soap. The end product is suitable for laundry or other cleaning soap.

The good news is that you were very smart and only made a small batch.

The other thing I would suggest is to change your settings for the lye and water. Instead of "Water as Percent of OIls," select "Lye Concentration." Then set it to 33% for cold process soap, or 25% for hot process soap. This will give you more consistent results, and will also cut down on the excess water that you had in the recipe. Between that and the liquid coconut oil, your bars could be soft and sticky for a long time. Most soapers prefer the hard coconut oil for bar soapmaking, and only use the liquid one for making liquid soap or non-soap products like lotions, etc.

Hope that helps, and keep soaping! We all have some soaps that turn out not so great, but it's a learning opportunity (per @TheGecko) so that next time will be better. :)
 
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Welcome to SMF, @Natchanon !

That's a bummer that your soap appears to have caught rancidity. Sadly, you probably have no choice than to dispose of it. But of course we will troubleshoot, so that this won't happen again.

What about the best-by dates of the oils? As a rule of thumb, the best-by date of the soao is about the best-by date of the oils that were used. The early stages of rancidity aren't easily visible/detectable when they happen within the oils, but they shorten the life span of the soap nonetheless. When in doubt, use oils as fresh as possible (freshly opened bottles, stored cool and dark).
Three weeks are a really short time for a soap to develop rancidity. Do you see signs of this? I. e. DOS aka Dreaded Orange Spots? Can you post a photograph of the actual bars? (SMF loves photos ;)).
Your 30% of RBO is a rather high percentage. This might or might not be part of the problem. (As reluctantly as I'm saying this, because I love RBO too, and I'm a bit jealous that you are where it comes from.) Quite some other soapers are using RBO at high percentages without issues, but others have encountered DOS.

With respect to the coconut oil – I'm not as confident as @AliOop. You're in Thailand, and I guess it's not much colder than 76°F/24°C where you store your oils. I've often seen coconut “oil” in Asian stores, obviously from southeast Asia, in narrow-neck bottles, but completely solidified. “Coconut that you have to melt” might well be hydrogenated coconut (92°F). If you want to be sure which type you had, place a bit of it into the fridge. If it freezes into a hard solid, then it's “regular” 76°F coconut oil; only if it stays liquid or becomes turbid/creamy then it's fractionated (“MCT oil”). With the high global price for MCT oil, and its different digestive properties, I can hardly imagine that this is used anywhere as a staple cooking oil.

Anyway. I hope you're getting behind your issues, and we're looking forward to your future “carreer” 😃.
 

TheGecko

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The problem could be a combination of things, some mentioned previous, but I'll repeat with some others.

1. 27% Lye Concentration is a lot of water that you don't need. I would suggest going with a 33% Lye Concentration.

2. Cooking Oils from the store. This in itself it not necessarily a bad thing, but you do want to be careful to a) check the date to make sure it hasn't been a year since it was originally produced, b) make sure that it is 100% of the oil and not a 'blend'.

3. Coconut Oil 92 degrees vs Coconut Oil 76 degrees. Fractionated Coconut Oil is made from Regular Coconut Oil so on the surface there doesn't appear to much difference...one is a liquid, one is a solid, but my understanding is that there is a difference in the fatty acid composition of both. While the main fatty acid in Coconut Oil is the 12-carbon lauric acid, most or all of this is removed when it is fractionated. And the long-chain fatty acids present in regular CO, they have been eliminated in Regular CO. Given the amount of science/magic that takes place during the curing process...it's going to make a difference.

4. Leaving your soap out in the direct sunlight for a couple of weeks.

5. Using twice the recommended amount of fragrance. Which brings up...is the fragrance you purchased made for soap?
 

Natchanon

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The problem could be a combination of things, some mentioned previous, but I'll repeat with some others.

1. 27% Lye Concentration is a lot of water that you don't need. I would suggest going with a 33% Lye Concentration.

2. Cooking Oils from the store. This in itself it not necessarily a bad thing, but you do want to be careful to a) check the date to make sure it hasn't been a year since it was originally produced, b) make sure that it is 100% of the oil and not a 'blend'.

3. Coconut Oil 92 degrees vs Coconut Oil 76 degrees. Fractionated Coconut Oil is made from Regular Coconut Oil so on the surface there doesn't appear to much difference...one is a liquid, one is a solid, but my understanding is that there is a difference in the fatty acid composition of both. While the main fatty acid in Coconut Oil is the 12-carbon lauric acid, most or all of this is removed when it is fractionated. And the long-chain fatty acids present in regular CO, they have been eliminated in Regular CO. Given the amount of science/magic that takes place during the curing process...it's going to make a difference.

4. Leaving your soap out in the direct sunlight for a couple of weeks.

5. Using twice the recommended amount of fragrance. Which brings up...is the fragrance you purchased made for soap?
Thank you. I have some more question.

1. I'd made another batch prior to this batch at my friend's house. She said she didn't leave them in the sun but it still smelled rancid. I think we can safely cross that out.
The fragrance oil I used is for soap making, at least that's what the store says. It's a big online store that carries a lot of essential oils and aromatic products, so I think it's quite trustworthy.

2. The two bars I used yesterday smelled fine today. I tested them again and the rancidity returns, so it only smells bad when it lather up

3. The bubbles don't come up as easily as store-bought soap. You have scrub it quite a few times. If you don't, the bubbles don't appear at all, and you'll just have a slippery oily substance on your hands.
Here are the pictures. I separated out the two bars I tested.

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Welcome to SMF, @Natchanon !

That's a bummer that your soap appears to have caught rancidity. Sadly, you probably have no choice than to dispose of it. But of course we will troubleshoot, so that this won't happen again.

What about the best-by dates of the oils? As a rule of thumb, the best-by date of the soao is about the best-by date of the oils that were used. The early stages of rancidity aren't easily visible/detectable when they happen within the oils, but they shorten the life span of the soap nonetheless. When in doubt, use oils as fresh as possible (freshly opened bottles, stored cool and dark).
Three weeks are a really short time for a soap to develop rancidity. Do you see signs of this? I. e. DOS aka Dreaded Orange Spots? Can you post a photograph of the actual bars? (SMF loves photos ;)).
Your 30% of RBO is a rather high percentage. This might or might not be part of the problem. (As reluctantly as I'm saying this, because I love RBO too, and I'm a bit jealous that you are where it comes from.) Quite some other soapers are using RBO at high percentages without issues, but others have encountered DOS.

With respect to the coconut oil – I'm not as confident as @AliOop. You're in Thailand, and I guess it's not much colder than 76°F/24°C where you store your oils. I've often seen coconut “oil” in Asian stores, obviously from southeast Asia, in narrow-neck bottles, but completely solidified. “Coconut that you have to melt” might well be hydrogenated coconut (92°F). If you want to be sure which type you had, place a bit of it into the fridge. If it freezes into a hard solid, then it's “regular” 76°F coconut oil; only if it stays liquid or becomes turbid/creamy then it's fractionated (“MCT oil”). With the high global price for MCT oil, and its different digestive properties, I can hardly imagine that this is used anywhere as a staple cooking oil.

Anyway. I hope you're getting behind your issues, and we're looking forward to your future “carreer” 😃.
I'd made another batch prior to this one at my friend's house. She said she didn't leave them in the sun but it still smelled rancid. I think we can safely cross that out.
The coconut oil was made in November 2020 and will expire in November 2022. I have no idea when the olive pomace oil was manufactured, but it will expire in May 2022. The rice bran oil strangely doesn't have a date on the bottle despite being of highly regarded brand in Thailand. I don't see any orange spots, but here are the photos. I separated out the two bars I tested. The bubbles don't come up as easily as store-bought soap. You have scrub it quite a few times. If you don't, the bubbles don't appear at all, and you'll just have a slippery oily substance on your hands. They smelled fine today after being left to dry. I tested them again and the rancidity returns, so it only smells bad when it lather up.
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The soaps themselves look fine! You have some soda ash (the white stuff visible on top of the turquoise bar), which is a purely cosmetic thing. Your recipe should give you a soap that gives off lather easily and in abundant amounts: the coconut oil should guarantee this.
If you have DOS, it would be difficult to see in the orange bars, and three weeks is also a quite short time for the eyes for them to appear – your nose is apparently more sensitive/reliable. What surprises me is your observation that the rancid smell only develops when the soap is in use. In the rare cases when I had rancidity troubles, they either were only visible to the eye (= DOS), or the smell would be noticeable on dry bars too.

I'm now somewhat out of ideas as well. What source of water did you use?

It might be worth a debug batch. Use the same oil blend (ideally, oils from the same bottles), but increase lye concentration to 33% (2.0:1 lye). Don't add fragrance nor colourants. Be very watchful of any off-scents during making and the curing time. Report back your findings.
 

Dawni

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How bad is the smell when used? And what kind of smell?

I noticed some of my soaps have "a smell" that isn't rancidity, and isn't the EOs or FOs, it's just a weird kind of soap smell.

I know what rancid soap smells like, I've had a few and they all have different rancid smells lol but I am saying the ones I'm speaking of do not smell rancid, but they do have a smell/scent only when wet/in use.

I'll describe them as a "salty" kind of "sweaty" smell lol

I am still trying to pinpoint what causes it. Thankfully, the ones I sell don't have it lol
 

Babyshoes

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I'm also wondering if the smell you're describing as rancid, is rather that you just dislike the combination of oils you've used when saponified... 🤔
All soap has a smell of some sort, which some folks are more sensitive to than others. Fragrance oils cover that up to some extent, but it's more obvious to me when wet.
 

bumbleklutz

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Hmmm...I can sympathize. I've had this happen, and unfortunately, I never found a reason for it. I found a 3 year old bar that I had forgotten about. I remember making this batch because of how much I enjoyed using this soap when it was younger. It was fragranced with Nurture Soaps "Satsuma" and still smelled nice when I found it. There was no scent of rancidity, and no visual signs of DOS whatsoever. However, when I used this bar in the shower it stank. I mean really awful, like rotting fish. I set the bar aside, and miraculously when it was dry...its smelled just fine. Like, you guessed it "Satsuma". I thought maybe my nose was just off that day, so I tried it again in the shower. Again, rotting fish smell. I've kept that bar to periodically check for signs of DOS or rancidity, but 6 months later it's still looking and smelling good when dry and like rotting fish when wet. Sometimes soap does "stuff" and we never do figure out the cause.
 

TheGecko

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The fragrance oil I used is for soap making, at least that's what the store says. It's a big online store that carries a lot of essential oils and aromatic products, so I think it's quite trustworthy.

Not necessarily. My sister bought me a beautiful set of Micas from a very well known online company...she and her friends use them all the time in their crafting and it says right on the website that it is safe for skin, that it is "AP certified to be non-tonic and is cosmetic grade" and it most likely is...but it doesn't mean that it can be used in soap making. Which is a shame since the colors are absolutely gorgeous!

One of the things I have learned over the last two years is just because something says that it's 'body safe' doesn't mean that it is safe to use in skin products. And just because you can use it in M&P Soap, doesn't mean you can use it in CP/HP Soap...something I found out.

The two bars I used yesterday smelled fine today. I tested them again and the rancidity returns, so it only smells bad when it lather up

That tells me that it's your scent and not your oils. If your oils had been rancid you would see it and you would smell it all the time.

The bubbles don't come up as easily as store-bought soap. You have scrub it quite a few times. If you don't, the bubbles don't appear at all, and you'll just have a slippery oily substance on your hands.

That's because commercial soaps, though they may be made with fats and lye, are processed differently. First is that they are milled to make them smoother, harder and slicker. Then they add various additives to make the soap more 'bubbly', to produce lots of 'lather', etc. And the reason why artisan soap feels like there is a 'slippery oily substance on your hands' is simply because you are used to how commercial soap treat your skin...which is to strip all the natural oils.

When I first started using my soap, I had to get used to that 'not squeaky clean' feeling that I got with commercial soaps. Now I don't even notice it, but you bet I notice when I have to use a commercial soap...I don't even make it out of the ladies room before my hands start itching from how dry they are.

My recommendation is to make a small batch of uncolored, unscented soap, let it cure for at least four weeks and then try it.
 

Natchanon

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The soaps themselves look fine! You have some soda ash (the white stuff visible on top of the turquoise bar), which is a purely cosmetic thing. Your recipe should give you a soap that gives off lather easily and in abundant amounts: the coconut oil should guarantee this.
If you have DOS, it would be difficult to see in the orange bars, and three weeks is also a quite short time for the eyes for them to appear – your nose is apparently more sensitive/reliable. What surprises me is your observation that the rancid smell only develops when the soap is in use. In the rare cases when I had rancidity troubles, they either were only visible to the eye (= DOS), or the smell would be noticeable on dry bars too.

I'm now somewhat out of ideas as well. What source of water did you use?

It might be worth a debug batch. Use the same oil blend (ideally, oils from the same bottles), but increase lye concentration to 33% (2.0:1 lye). Don't add fragrance nor colourants. Be very watchful of any off-scents during making and the curing time. Report back your findings.
Thank you. I used distilled water that we put in cars. It could be the lye concentration. I make another two more, one with the same scent and one without. That would isolate the fragrance oil if it truly is the problem.
 
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