How much DOS is too much DOS?

[elurah]

Hi lovely Soapers,

I wanted to reach out about the DOS. I have three 4 oz bars out of about 15lbs of soap that have one DOS mark. They are from different batches, all made 1+ year ago. They were not next to each other. They were handled by hand without gloves. They are stored on a glass surface. Notably, these bars are pure white (from base recipe, not from colorant), so it is possible that other pigmented bars also have it but I can not see it. However, most of my bars do not have pigment.

The base recipe is high CO/high SF (20%).

So, what amount of DOS is acceptable or moves you to change your formulation? Is there a shelf-life threshold that you find acceptable, like more than 12 or 24 months, for DOS to crop up? If it is just a few spots as opposed to rampant?

My current move is to drop my SF by 15% and try adding Vit E, although the research has not shown much benefit. I remember someone (?? Thank you whoever you are) posting this article:

http://cavemanchemistry.com/DreadedOrangeSpot-Dunn.pdf

So my plan is to try ROE and ROE + EDTA for future batches and see how they perform.

Any advice would be greatly appreciated! I love my high SF bars but I am always up to trying different variations on a theme.

Last bit: I make these soaps for myself, friends, and family. I think it would be cool to sell at a farmer's market one day, but that will not happen for another 5 years.

 

[BrewerGeorge]

Twelve ounces out of 15 lbs is a 5% rate of failure. I would personally consider that acceptable and assume those 3 bars were somehow contaminated from outside. That said, the ROE/EDTA definitely can't hurt, but I probably wouldn't alter the SF if that's what I liked.

 

[jcandleattic]

assume those 3 bars were somehow contaminated from outside.

I tend to agree. If it were a recipe problem, IMO it would affect more than just 3 bars of the batch. There are sooo many reasons that DOS happens, and sometimes it really is just a "fluke".

 

[Lin19687]

If you are selling , For me, I would say None.

If just for you, who cares it's all good.
Friends/family... well that depends on your friends/family

 

[elurah]

If you are selling , For me, I would say None.

If just for you, who cares it's all good.
Friends/family... well that depends on your friends/family

When you say none, after what time period? None after 2 years? 5 years? If there is any Sf% wouldn't rancidity occur eventually?

Allie

 

[jcandleattic]

If there is any Sf% wouldn't rancidity occur eventually?

Not necessarily. It really depends on several factors. Age of oils used, curing conditions, weather conditions, etc.,
I have a few bars left that were superfatted with 20% that were made in 2009, that are as pristine now as when I put them on my curing shelf. (They are salt bars, if that makes a difference) and none have contracted DOS.

 

[DeeAnna]

There are spots of rancidity (DOS) and there is overall rancidity. While they are both examples of rancidity, DOS most likely comes from individual bits of contamination and overall rancidity comes from a source of overall contamination. We were talking about this in another thread -- https://www.soapmakingforum.com/threads/soap-spoilage.69752/

 

[elurah]

Thanks for the reply and the link to that recent thread everyone! I think the problem is incidental contamination as opposed to the recipe or the ingredients themselves.

DeeAnna, I think you are the one who posted that article that I saved. Thank you again! I think I will try adding EDTA + ROE moving forward.

Warmly,
Allie

 

[earlene]

I use ROE + EDTA and not only does it help prevent DOS, it also helps reduce soap scum. In fact, I have seen a remarkable decrease in soap scum since adding EDTA to the mix.

Some of my soaps are over two years old without DOS, although I have had DOS even with the ROE + EDTA combination, but those seem to be formula related more than time related (too much linoleic and linolenic acids in the oils). I have no way of figuring out the percentage, though like BG did above. I agree that 5% seems acceptable.

 

[SaltedFig]

The steps you are taking, reducing the superfat by 15% and adding an antioxidant/chelator combination, should go a long way to extending the time it takes for these spots to appear.

... what amount of DOS is acceptable or moves you to change your formulation? Is there a shelf-life threshold that you find acceptable, like more than 12 or 24 months, for DOS to crop up? If it is just a few spots as opposed to rampant?

To answer your question, I personally would aim to reduce the occurrence of DOS as far as possible, but at some point, unless you are working with quality controlled inputs (ingredients/production environment/method), you are likely to experience loss over time beyond what you can control.

Personally I am not happy to lose any bars under 2 years, and if this occurs I look for a reason within my original ingredients, recipe and processes (including curing and storage), however if your 20% superfat was for a coconut recipe without salt, then the shelf life of your soap will be moved closer to the original shelf life of the oil itself (from the shelf life of pure soap).

The last time I had a (roughly) 5% loss rate in young bars (under 2), I was able to narrow it down to contact with (coated and paper covered) metal racks as the cause, and eliminated that as an on-going issue. For yours, as I said, the steps you are already taking should help significantly, but I would also recommend looking at adding a cotton (or similar) material layer under the soaps, so that there is not an air-less seal where the soap meets the glass.

 

[elurah]

Hi Saltedfig,

Thank you for all of the great advice. The bars were for a brief moment on a stainless steel rack but then moved to the glass. That could be the culprit. I will try adding some cotton lining to the bottom so that they can breathe a bit.

Honestly, I think my setup is too prone to contamination as it is. I use HDPE 2L short graduated beakers and acrylic molds with butcher paper but I wash everything by hand and I think that leaves room for error. I will do some searches on GMP approved cleaning setups.

Recipe wise, I am checking out 15% SF and I plan to add a chelator/antioxidant. I will start with EDTA and ROE but I am interested in doing research to see if there are any other combinations that work! Will share what a find in a year or two

 

[DeeAnna]

Citrate and BHT are another effective chelator/antioxidant pair.

 

[missingnojo]

I use ROE + EDTA and not only does it help prevent DOS, it also helps reduce soap scum. In fact, I have seen a remarkable decrease in soap scum since adding EDTA to the mix.

Some of my soaps are over two years old without DOS, although I have had DOS even with the ROE + EDTA combination, but those seem to be formula related more than time-related (too much linoleic and linolenic acids in the oils). I have no way of figuring out the percentage, though like BG did above. I agree that 5% seems acceptable.

Wouldn't adding Citric acid prevent soap scum as well instead of using EDTA? And what about Vit E instead of ROE? Has anyone done this with success?

 

[DeeAnna]

Vitamin E is not an effective antioxidant for soap. Kevin Dunn did experiments that showed Vitamin E was no better than nothing at all.

Citrate prevents soap scum and DOS, but informal discussion amongst soapers suggests citrate is not quite as effective as EDTA.

 

[earlene]

Wouldn't adding Citric acid prevent soap scum as well instead of using EDTA? And what about Vit E instead of ROE? Has anyone done this with success?

Yes, to the first question, but that's not what I use. I base my use of ROE + EDTA on the results Dr. Kevin Dunn got in his research (here), but that is not the only effective combination. The article is fairly short and easy to understand, so I think you will find your answers there. Vitamin E was not found to be very effective. I have no experience using Citrate + BHT, but that combination was found to be the most effective against DOS in his experiments.

DeeAnna's website has good information on how to create Citrate, which is formed when Citric Acid reacts with lye. See this link.

Re: questions #2 & #3: As far as preventing DOS, Dunn's results showed that Citrate + Vitamin E was not very effective, so personally, I wouldn't bother. I prefer to take vitamin E orally for it's health benefits than waste it in soap.

Caveate to use of Citrate for DOS prevention: Dunn's results show that it works in combination with BHT. So you would need to add BHT. I think there are a couple of SMF members who do use that combination, but currently don't recall who exactly. Maybe one of them will respond.

 

[DeeAnna]

"...I think there are a couple of SMF members who do use that combination..."

Earlene -- I'm pretty sure Carolyn does (cmzaha).