Dos

[DONNAMAC]

In your opinion, what is the main culprit for DOS? I used the same recipe for several batches and 2 of them have DOS, and the others don't. Could the fo cause this?

[ChrisR]

Heat and humidity seem to be the most logical culprit. However, short shelf life oils can also do it, sometimes fresh fruit or veggies. Personally any batch I've made with RBO has ended up with DOS, but lots of others use it without a problem. Unfortunately, I don't think there's just one answer.

[CareBear]

Heat, humidity, metal racks, sensitive oils, old oils, some colorants perhaps...

[topofmurrayhill]

So what is it exactly...some kind of fungus?

[CareBear]

this may explain a bit. but no, it's rancidity/oxidation not fungus.

http://candleandsoap.about.com/gi/dynamic/offsite.htm?zi=1/XJ&sdn=candleandsoap&cdn=homegarden&tm=16&f=00&su=p284.8.150.ip_&tt=8&bt=1&bts=1&zu=http%3A//www.soapnaturally.org/DOS.html

[eugenia]

So what is it exactly...some kind of fungus?

They are a mystery Top. Sometimes they can inflict just a few bars in a batch. If you get them, you will know as they are always orange spots.

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[Roxanne]

I used the same recipe for several batches and 2 of them have DOS, and the others don't. Could the fo cause this?

I don't think FOs cause DOS. I do believe, though, that most FOs and EOs contain ingredients that act as antioxidants and help prevent DOS, and some don't. I say this because in my experience, unscented soap is far more likely to develop DOS than any scented soap. Next most likely for me is lavender EO soap, followed by the magnolia FO I use. I use ROE as an antioxidant in my soaps, and it really helps control DOS (although it isn't a sure-fire cure).

I agree with Chris about heat and humidity, and I think humidity is worse than heat.

[Mnhorsemom]

I have to vote for the heat/humidity theory. I had several batchs last summer end up with DOS,but have never had a problem soaping in cool/cold weather. I really made me mad cause I lost 4 batchs soap (actually I still use them doesn't seem to be a problem) ya sure can't sell soap with big ugle orange spots

[RobinInOR]

Heat always speeds up chemical reactions, so it would make sense that an increase in heat would help along any oxidation that is taking place. I rarely get DOS, living in a nice dry area, but I can tell that after a summer of markets, a few of my soaps are getting small spots of DOS. Heat, lots of UV..

This is an interesting article from a chemist who is also a soaper. http://cavemanchemistry.com/HsmgDos2006.pdf

[DONNAMAC]

Well, I live in Missouri, and it has been very hot and humid. But I soap in the AC, and cure in it too. Could that still be a problem?. Oh, and I do use rbo in a lot of my soap. Does DOS hurt your soap in any way? I know it is not pretty, but I don't sell, just use it in the family and some friends. Thanks to everyone for your comments. This board is so helpful.

[topofmurrayhill]

Thanks Robin, that's interesting and helpful.

Now I understand. DOS is caused by lack of preservatives.

Seriously, it does make sense that the shelf life of your oils is an important consideration in avoiding DOS, but I've noticed there's a lot of conflicting information about the shelf life of oils.

I've started looking at the iodine value. That's a rough indicator of the degree of unsaturation of the fatty acids in the oil. Unsaturated fats are more reactive and prone to oxidation than saturated fats.

Based on this, I've hesitated to work with RBO. I guess it's a good OO sub in that it contributes well (for a soft oil) to hardness, but the iodine value is much higher. Put olive oil in the fridge and it solidifies. That's gotta be a good sign.

[RobinInOR]

I use RBO in high percentage, no olive, yuck I dislike olive. I know a lot of people who get horrible DOS with RBO. I rarely do, and I figure they're living in much more humid/hot areas than I am. Plus I *never* have my soap stored in plastic as it cures - they're in cardboard boxes so the moisture can evaporate and they can 'breathe'

[Scented]

Well, I live in Missouri, and it has been very hot and humid. But I soap in the AC, and cure in it too. Could that still be a problem?. Oh, and I do use rbo in a lot of my soap. Does DOS hurt your soap in any way? I know it is not pretty, but I don't sell, just use it in the family and some friends. Thanks to everyone for your comments. This board is so helpful.

Not far from you and last summer was a killer for heat and humidity more than this year. Last year I had it on a couple of batches. Others I didn't. Those I didn't have it on had no canola either.

I soaped in AC and thought I was curing in it too, but that heat and humidity gets in anywhere.