Bad behaved yellow. Yellow / brown to mask DOS?

[Garden Gives Me Joy]

Why is the rich yellow color from annatto fading so strangely in S38? The color of both bars started out being homogenous and with the same intense yellow. (20% of oil was infused with annatto seeds at 1 g seeds to 1 g oil before seeds were strained off.) However, the color of S38 is fading in the most dramatic way; from around the edges first. Unsure whether this is happening because these are brine soaps, S38 has more salt and or my tropical climate has had a few humid days lately. Happy for possible explanations.

Experiment S38 (31 Jan 2021)
Water preparation: Salt @ 30% of water. Water @ 38% ppo was boiled til reduced to 30% ppo. Consequently, lye added to brine with higher salt concentration. (Pictured here as half disc)

Experiment S34 (31 Jan 2021)
Water preparation: Salt @ 30% of water. Water @ 34% ppo was boiled til reduced to 30% ppo. Consequently, lye added to brine with lower salt concentration. (Pictured here as full disc)


Trick of the trade or waste of time?
On a different note; this experiment was inspired by something I wanted to figure out. Am I the only one who has considered coloring soap to preemptively mask potential DOS? If my information is correct, DOS is only an eye sore. In other words, it is in no way a health hazard. I used annatto to make these otherwise white soaps yellow.

If this idea is at all possible, how would one plan the design? .... I suppose brine might now be the best combination? I figure cacao would be useful for brown. Happy for your photos with explanations and ideas if possible.

 

[Tara_H]

If my information is correct, DOS is only an eye sore.

My understanding is that it's caused by rancid oils, so in addition to the discoloration, there is also a bad smell and progressive softening of the soap, both of which will spread from the affected area.

 

[amd]

Am I the only one who has considered coloring soap to preemptively mask potential DOS? If my information is correct, DOS is only an eye sore. In other words, it is in no way a health hazard.

DOS indicates soap that was poorly made. Trying to mask it is fine if you only make soap for yourself, but if you are selling, this is extremely deceptive to customers. A very poor business practice. I do not enjoy using soap that DOS, and definitely do not want my customers using it.

 

[earlene]

Trick of the trade or waste of time?
On a different note; this experiment was inspired by something I wanted to figure out. Am I the only one who has considered coloring soap to preemptively mask potential DOS? If my information is correct, DOS is only an eye sore. In other words, it is in no way a health hazard. I used annatto to make these otherwise white soaps yellow.

I can tell you that advanced DOS is NOTHING I would want to wash my body with!!! I had some early soaps (made when I was brand new to soapmaking) turn bad and left them sitting around for observation way beyond the time the smell was tolerable. That smell is one of the grossest odors I have ever had in my house. (and I have smelled some pretty awful smells over the course of my 7+ decades of life).

I doubt there is any fragrance that would truly mask the odor, and even if there was, the very idea of planning to include DOS in your soap seems rather odd, to say the least. I think it's better to strive toward Good Manufacturing Practice that would work toward DOS prevention rather than working toward a way to work with it and produce sub-standard soap. Even if you only make soap for yourself (not even your family should be given soap with DOS), why would you want to settle for less than good soap?

Now, as to it being a health hazard. Yes, it can be. I worked with an Infection Control Nurse who did an in-house study in our hospital (I really have no idea if she ever published, however) of bar soap, and documented growth of microorganisms on hand soap that was left to wallow in non-draining soap dishes. Rancid soap is even more likely to contain microorganisms (both internally and on the surface); mold, mildew, bacteria, viruses, even yeast could be growing in rancid soap especially once it gets or stays wet. And just because you cannot see it, doesn't meant it's not there. One by-product of rancidity can be malondialdehyde (MDA), which apparently can penetrate the skin, and although I suspect you wouldn't soak in a tub with rancid soap because the smell is so horrible, if you did that would certainly give it some opportunity to penetrate your skin. MDA is indicated in cellular damage at the dermal level and certain skin disorders as well as increases in certain cancers. Because of that, inconclusive though the information is at this point, I certainly wouldn't want to introduce such by-products of rancidity into my skin.

Some references:
https://classicbells.com/soap/rancidity.asphttps://www.soapqueen.com/tag/rancidity/https://www.frontiersin.org/articles/10.3389/fphar.2020.00785/fullhttps://pubmed.ncbi.nlm.nih.gov/8877062/https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6690246/https://jemds.com/data_pdf/mary vinee--feb-10-.pdfhttps://www.sciencedirect.com/topics/agricultural-and-biological-sciences/thiobarbituric-acid

 

[dibbles]

I'm not trying to pile on here especially since I don't know if you sell, plan to sell, or if this is just for personal use. But I do have to agree with the others in that regardless of the intended end user, a soap with DOS is not something you would want to use. And is absolutely not something you should consider selling.

As to the color fade, I have found that my annatto seed infused oil soaps will fade a little over time, but the color remains consistent throughout the bar rather than fading from the edges to the center. Do you store your soaps in a dark place, or are they exposed to light?

 

[Garden Gives Me Joy]

[...]
I doubt there is any fragrance that would truly mask the odor, and even if there was, the very idea of planning to include DOS in your soap seems rather odd, to say the least. I think it's better to strive toward Good Manufacturing Practice that would work toward DOS prevention rather than working toward a way to work with it and produce sub-standard soap. [...]

Agreed that DOS and rancidity should not be an acceptable outcome. Formulation is always the best way. Thanks for informing me and re-newing my appreciation for avoiding DOS like the plague.

However, just for the sake of clarity, I am not planning / striving to make sub-standard soap that I know has DOS. Perhaps I was not sufficiently clear in my original post?

I have been experimenting with numerous 1-bar iterations to see what happens when I do something vs another ... The experiments also extend to intentionally exposing the soaps to sub-optimal conditions as consumers might, especially since my extremely humid tropical rain forest climate makes dealing with natural soaps challenging in ways that I never imagined (having come from a much more arid environment). I realize people like to display natural soaps for too long rather than use them which, in my current climate scenario will only exacerbate the challenge.

Since beginning to soap in late 2015, I have experienced DOS once in one of my numerous experiments and, in one other recent case, really smelly rancidity. (I documented the rancidity case on this forum, just to realize the problem was likely due to the metal strainer I used whose rim elements is cheap metal despite the stainless steel inner part. Parts of the rim started to rust after I made that soap. (The problem did not recur when I repeated the recipe).

As much as possible, I want to apply all the ways (vitamin E, cool base oil storage, etc) I could find of managing problems over which I have very little or no control. ... But, considering your good point (re the dangers of DOS and rancidity), maybe it would be best to continue with my uncolored Plain Jane approach so people can see the DOS hazard, if or when it actually happens. (FYI, I was only considering masking color, not the smell. I have not yet used fragrance oils in my soaps).

Ultimately, I figure my formulations must go to extremes in prevention re all the possible problems in an environment like mine.

....
No, have never sold.

Stored in a cupboard without any dehumidification. Unsure whether the soap's sweating every time it rains has anything to do with that strange fading pattern. The edges are however resting against the edges of a round container.
--

Just want to really thank everyone for the frank feedback!

 

[Obsidian]

Natural colors are prone to fading, its just what they do.
Storing in the dark does help slow fading but I can imagine the humidity isn't helping. Maybe crack the cupboard and keep a small fan pointed at it would help with humidity.

If you have a lot of trouble with sweating, a dehumidifier may be the answer.

 

[Garden Gives Me Joy]

Natural colors are prone to fading, its just what they do.
Storing in the dark does help slow fading but I can imagine the humidity isn't helping. Maybe crack the cupboard and keep a small fan pointed at it would help with humidity.

If you have a lot of trouble with sweating, a dehumidifier may be the answer.

Indeed. However, my current intention is to do all the wrong / sub-optimal things to establish the limits, in part because consumers in my environment won't have fans or dehumidifiers. Most will never have AC in their homes either. I was shocked to note that many bathrooms here actually do not have windows. People are always fighting mold on their walls. I am starting to think that colorless Plain Jane is best - at least it might encourage people to use rather than display the soap.

 

[Obsidian]

You could always make one color soap, those should get used more then fancy swirled ones.

My grandmother never uses the pretty soaps I make so now I just do single colors for her.

 

[ResolvableOwl]

DOS best practice

Am I the only one who has considered coloring soap to preemptively mask potential DOS?

No.
But think twice if you want to do that. It gives you a false sense of security, you can't tell any longer if DOS is happening or not. Given the colour stays, which is a different topic.

Colour fading
Your semi-faded S38 annatto soap is puzzling, as well as the unreliable reproducibility with S34 (BTW It's a really clever idea to give soap batches boring numbers/identifiers to better refer to them afterwards).
Has the S38 a firm, massive texture, or is it porous?
I have a working hypothesis with carotene/vitamin E rich oils: vitamin E is a sacrificial antioxidant (scavenges reactive oxygen, but gets used up with time), and protects both carotenoids (colour from annatto/red palm oil/carrots/…) and unsaturated fatty acids from oxidation. When it's gone, oxygen decomposes the pigments and causes DOS (probably in this order).
Now, the rate at which this happens depends on many variables. Palm oil soap appeared to fade more rapidly when gelled. It might well be that your salt addition disturbed the microscopical structure, and allowed oxygen to diffuse into the bar more quickly than with the S34 bar. Who knows?

Do you use ROE?

 

[Garden Gives Me Joy]

DOS best practice

No.

But think twice if you want to do that. It gives you a false sense of security, you can't tell any longer if DOS is happening or not. Given the colour stays, which is a different topic.

Colour fading

Your semi-faded S38 annatto soap is puzzling, as well as the unreliable reproducibility with S34 (BTW It's a really clever idea to give soap batches boring numbers/identifiers to better refer to them afterwards).

Has the S38 a firm, massive texture, or is it porous?

I have a working hypothesis with carotene/vitamin E rich oils: vitamin E is a sacrificial antioxidant (scavenges reactive oxygen, but gets used up with time), and protects both carotenoids (colour from annatto/red palm oil/carrots/…) and unsaturated fatty acids from oxidation. When it's gone, oxygen decomposes the pigments and causes DOS (probably in this order).

Now, the rate at which this happens depends on many variables. Palm oil soap appeared to fade more rapidly when gelled. It might well be that your salt addition disturbed the microscopical structure, and allowed oxygen to diffuse into the bar more quickly than with the S34 bar. Who knows?

Do you use ROE?

Agreed re it being better to avoid using colori as a mask for the potential risk.

Re the texture of S38. S38 is not as firm and resistent to being dented as S34. I find this noteworthy given its higher salt concentration. Of course though, it has been sweating like crazy, much more than the S34. Outside of squeezing it to see if it crumbles, I am unsure how to assess the porosity of soap. I hope that answers your question.

Re ROE: Asked around but could not find a supplier in my current location. It seems that my only option is to import it from overseas. I have not yet found a supplier. I plan on using vitamin E in the meantime. I am growing in appreciation for the value of using antioxidants. When I do these 1-bar experiments I am trying to narrowly answer one or 2 questions (like 'could I achieve a much creamier non-crystalline salty bar by figuring how to dissolve more salt into water than is usually possible?', etc) ... And so I do not use scarcer ingredient x in that moment knowing I have no further use for the bars afterwards. In this higher vs lower salt experiment, I did not use an antioxidant / vitamin E (but used 2% citric acid). If I understand the science in your response; if I observe this soap further in my intentionally bad storage conditions, I will see it go completely rancid. ... and furthermore, without the extra help of added vitamin E (or ROE), the whitening is a sign that the pre-existing vit E is getting used up, which would be very ironic given one of my original questions.

So salt beyond S34's apx 10.2% of oils is a possible trigger then? Is there another lesson related to the limits to which water discounts are ideal in brine soaps?

Since sunflower oil is abundant and cheap here, I have used it as the only base oil and without any additives beyond those I am observing for many of these 1-bar experiments (like this one). Afterwards, I test entire formulations. Citric acid got included here mostly because I wondered whether it could still be dissolved after all that salt (and it is so cheap anyway). Since sunflower oil is soft and needs a miracle to create a hard bar at 100%, it was certainly noteworthy to observe the effect of salt without the help of harder baseoils. BUT, is it a fair assumption that observations in these experiments can always apply to other baseoils when combined more appropriately? Am I re-inventing the wheel? Afterall, I have pre-experimentation soaps for my different skin type with vitamin E that are over 2 years old and fine (despite having 10% SF, oats, avocado puree, etc). Is there a more efficient way?

 

[ResolvableOwl]

OK. Once after another.

Hardness/oil composition/recipe
How high do you intend to dose sunflower oil? Do you use regular (high-linoleic) sunflower oil, or the high-oleic variant? HO behave very similar to olive oil, and will give a castile-like soap; it is fine as a base oil (just nothing for the impatient). But HL, at rates above 30% can evoke terrible DOS/rancidity issues, along with it never becoming a really firm bar (at least for no-salt soap; I don't have experience with salt bars/brine soap).

And even if you can achieve a harder bar with salt addition, it'll still be very soluble, love to soak up water, swell up and become mushy. The difference between (dry) hardness and satisfactory durability under usage conditions is often underestimated, some soap calculators don't even display a “longevity” number.
That means that, e. g., adding coconut oil (which is easy to find and has other benefits too) won't help you too much in this respect: it is high-hardness but low-longevity. You need to lower the solubility. That's where oils high in palmitic/stearic, like palm, tallow, cocoa, or hydrogenated oils (soy wax), are good at.

I don't know what your intentions/goals are. When sunflower has a high priority but bar soap not so much, then you might push past all that salt/hard oil fuss by cooking liquid soap?

Oxidation protection
In case you want to use high-linoleic oils in major quantities, you definitely want to prevent DOS, even if it is for personal usage only. Have a look at DeeAnna's page on this topic, and links/references therein (ROE, EDTA etc.), and vitamin E (tl;dr: Don't rely on tocopherol for DOS protection).

Texture, porosity and oxidation
Salt crystals need space. They grow and push other things, like soft soap, aside. It is totally possible that your S38 bar has so many salt crystals in it that the soap around it just cannot hold the whole together as strongly as in S34. And/or they ease drainage of salt water/glycerol (sweating!) and subsequent intake of air and oxygen. We don't know; all this probably happens on a µm-scale and would need a microscope to detect anyway.
In any case, single-oil tests are fine to learn the theoretical high-percentage properties of the constituents (divide-and-conquer strategy), but experience shows that these findings are only partly portable to the final compound recipe.

Reinventing the wheel?
Yes, you do. Many do it, me included, and a lot more often than needed. My personal opinion on this is that it's better to repeat mistakes and understand rules, than to just apply them. (If you were into quick success, you wouldn't tinker around, but copy well-proven recipes.) As long as it is fun and you are learning about your limits and the limits of your ingredients, the worst outcome are unsightly soaps, and the best outcome is a trained intuition about what is easy, what is risky, and when to stop rather sooner than later.
Remember that an experiment with negative outcome is not a failure, but a precious contribution to the understanding of the possible.


ETA

I figure cacao would be useful for brown. Happy for your photos with explanations and ideas if possible.

https://www.soapmakingforum.com/threads/how-to-get-the-perfect-chocolate-bar-color.82694/