I was wondering if there is a reason for DOS. I have heard all kinds of opinions, but what are they? A reaction of some kind? :-?
Is there a reason for dos?
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navigator9
Well-Known Member
Google "Caveman Chemistry, Kevin Dunn, dos" 
The main cause of DOS stems from the oxidation of unsaturated soft/liquid oils in ones formula, especially those with a high linoleic content/short shelf-life, such as hemp oil, grapeseed oil, soybean oil, safflower oil , sunflower oil, the old Crisco formula, etc.... Also- letting ones soap come into contact with metals, such as curing them on uncoated metal curing racks- or using very hard water with a high mineral/ metal content in your formula (instead of distilled) can also cause DOS.
IrishLass
IrishLass
The main cause of DOS stems from the oxidation of unsaturated soft/liquid oils in ones formula, especially those with a high linoleic content/short shelf-life, such as hemp oil, grapeseed oil, soybean oil, safflower oil , sunflower oil, the old Crisco formula, etc.... Also- letting ones soap come into contact with metals, such as curing them on uncoated metal curing racks- or using very hard water with a high mineral/ metal content in your formula (instead of distilled) can also cause DOS.
IrishLass
Two oils I use is grapeseed and soybean oils. Just recently I started using sunflower oil. I know this is a crazy thought, but, can soap ash be a part of dos? I just have to ask.
kchaystack
Supporting Member
Soda ash is caused by the reaction of your lye with the carbon dioxide in the air. If your oils are saponifying slower so there is more unreacted alkali that is exposed to the air, then yes. But I do not know if those 2 oils are slower to react than the steric or palmic oils. Maybe DeeAnna or TOMH will wander by and comment
Interesting, I noticed that when I use Lavender eo, I get dos more. I have had a few on my AC soap; but lavender is the worse. I also use kaolin clay; about a tsp/53 oz of oil, I started doing this a while ago and that's when I noticed the oranges spots. Will do a test batch with no kaolin and see how it does. Thanks. I wondered about the ash because the soap starts out good and as time moves, that's when I began to see them.
You're thinking one thing that happens over time causes the other problem that also happens over time. That's not correct. It's the same as deciding gray hair comes from wrinkles. They're related to age, but one doesn't cause the other.
www.soapmakingforum.com/showthread.php?t=60691
http://www.soapmakingforum.com/showthread.php?t=58256
www.soapmakingforum.com/showthread.php?t=60691
http://www.soapmakingforum.com/showthread.php?t=58256
kchaystack
Supporting Member
Ok, I am sorry I did not communicate my thoughts very well. I meant to say, yes the oils you use could lead to worse soda ash. But I do not think your DOS problems are due to soda ash.
I also doubt your lavender EO or kaolin clay cause your DOS. I think it is the fact you are using oils that are pretty well known to have a short shelf life - so go rancid sooner - is the cause of your DOS.
KC -- Fresh lavender EO is fine, but lavender EO can oxidize and oxidized lavender can trigger rancidity/DOS. (As well as cause irritation to the skin!) I have had a link to something by Robert Tisserand and/or Kevin Dunn that touched on this, but I can't find the reference today.
I've seen this for myself in an unintentional experiment I did early on in my soaping misadventures. I scented half of a soap batch with peppermint EO and the other half with lavender EO. Both halves of the batch eventually turned all-over rancid, but the lavender half turned much earlier than the peppermint half. My conclusion is that if rancidity (DOS) is going to happen, lavender EO (and perhaps other EOs that I'm not aware of) can accelerate the process. The use of grapeseed, soybean, and regular (not High Oleic) sunflower do make all-over rancidity more likely.
I'm not certain about clays -- people don't generally point to them as the culprits for rancidity. I suppose some clays might have certain metals that would trigger spots of DOS perhaps, but I've not heard anything concrete about that issue.
I've seen this for myself in an unintentional experiment I did early on in my soaping misadventures. I scented half of a soap batch with peppermint EO and the other half with lavender EO. Both halves of the batch eventually turned all-over rancid, but the lavender half turned much earlier than the peppermint half. My conclusion is that if rancidity (DOS) is going to happen, lavender EO (and perhaps other EOs that I'm not aware of) can accelerate the process. The use of grapeseed, soybean, and regular (not High Oleic) sunflower do make all-over rancidity more likely.
I'm not certain about clays -- people don't generally point to them as the culprits for rancidity. I suppose some clays might have certain metals that would trigger spots of DOS perhaps, but I've not heard anything concrete about that issue.
kchaystack
Supporting Member
Yeah, I don't use much in the way of EO's so that makes sense. And I thought about the clay not being refined to remove any metallic contaminates. Maybe if it isn't meant for cosmetic use it is more likely.
But really, the first thing I would do to troubleshoot this problem is change the recipe to lower the linolenic and linoleic oils to under 15%. Then I would look at the age of the EO and clay.
Soap making is so inconsistent.....I have not had an issue with DOS till last year. When I thought I had all the answers, I get a new question thrown at me. :cry::cry::cry:. I am going to do a test batch today and I will leave out the clay to start. Thanks for all the feedback from every one.
The only time I've seen DOS on a bar I made was in a batch scented with lavender EO. The base oils I used were olive (50%), shea (25%), and coconut (25%)--other than the lavender, nothing else is DOS-prone.
Soap making is so inconsistent.....I have not had an issue with DOS till last year. When I thought I had all the answers, I get a new question thrown at me. :cry::cry::cry:. I am going to do a test batch today and I will leave out the clay to start. Thanks for all the feedback from every one.
Frankly, any soap made with any fats can potentially become all-over rancid or get DOS. Sooner or later. Maybe not this batch or the next, but the one down the road a ways. And the triggers for the rancidity/DOS will vary.
If a fat can go rancid all on its own, it can go rancid when in soap. Soap is an organic material in the sense that the fats in soap come from living organisms. The process of decomposition -- which is what rancidity basically is -- is a normal stage in the ecological cycle of returning the fats back to nature. For us to have the expectation that we can entirely prevent this ... is a bit unrealistic.
I certainly think it's good practice to minimize the chance of rancidity within the normal lifetime of a soap bar (say a year or maybe 2) and even longer. There are many things that a soaper can do to accomplish this. But rancidity/DOS is gonna happen to every soaper someday. Even the big commercial soap companies have to deal with this issue -- controlling rancidity/DOS/discoloration is a common thread in soap making technology manuals from the 1800s through the modern day.
If a fat can go rancid all on its own, it can go rancid when in soap. Soap is an organic material in the sense that the fats in soap come from living organisms. The process of decomposition -- which is what rancidity basically is -- is a normal stage in the ecological cycle of returning the fats back to nature. For us to have the expectation that we can entirely prevent this ... is a bit unrealistic.
I certainly think it's good practice to minimize the chance of rancidity within the normal lifetime of a soap bar (say a year or maybe 2) and even longer. There are many things that a soaper can do to accomplish this. But rancidity/DOS is gonna happen to every soaper someday. Even the big commercial soap companies have to deal with this issue -- controlling rancidity/DOS/discoloration is a common thread in soap making technology manuals from the 1800s through the modern day.
Soapmaker145
Well-Known Member
I've never had a problem with Lavender but EO/FOs have been the main cause of the DOS I've seen since I started testing FOs. I can pour 50 testers using the same batter and find DOS (a year later) in a handful of them. Some suppliers are worse than others, most likely because they tend to build many of their fragrances on the same base aroma molecules. Some suppliers are surprisingly clean which makes me wonder if it is a diluent in the FOs that is causing the problem.
You are not that far off on the Kaolin. As Deeanna said, it is a natural mined product and is highly variable. If the batch you have has unusual/higher mineral content, you'll have a problem. This is the reason I try not to use it unless the FO is very light.
Polyunsaturated oils tend to be more problematic but once DOS starts, it'll eventually spread. Polyunsaturated oils in my experience haven't been enough on their own to cause DOS. They need a catalyst in the form of a metal or a chemical to accelerate the process.
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I've been doing several experiments with a variety of essential oils and natural colourants over the last couple of months and deliberately chose a cheapo recipe including shop bought rapeseed oil, despite the risk of DOS. It had a use by date of Dec 17. My lemongrass and poppyseed and geranium soaps seem fine. The peppermint and tea tree went spotty immediately - I mean before unmoulding, with funny paler green spots amongst the 1970s avocado bathroom suite colour I get from using green tea wax. These pale spots turned brown and the soap stated to smell off within two weeks! Two further batches peppermint and tea tree with more peppermint in proportion to tea tree and peppermint and ginger have not shown any signs of going off so far, though they are only about three weeks old. The orange ones also seem fine though are so spotty with powdered orange peel its a bit hard to tell! I didn't use lavender with this particular recipe but I've used lavender oil a few times without trouble.
The only other time I've experience DOS was with a tallow recipe but I replaced the olive oil with rapeseed again because I was going for a reduced "soap miles" soap, but this developed brown smudges rather than spots. So DOS seems to be a bit random to me. Though rapeseed oil seems prone, why it is worse in some cases than others, even when using the same essential oils from the same bottles, is a bit weird. Incidentally I gave one of the DOSed mint soaps to a work colleague - he couldn't get the off smell - and he loved it! I do have a couple of ancient 100% olive oil soaps I made when first starting soaping about 3 to 4 years ago. They are shrivelled up little rock hard lumps and are a bit brown round the edges but no actual DOS and no bad smell and are fine in use. The first batch of mint soaps are finishing off their curing in the shed where I can't smell them. I guess they'll end up in the bin eventually.
The only other time I've experience DOS was with a tallow recipe but I replaced the olive oil with rapeseed again because I was going for a reduced "soap miles" soap, but this developed brown smudges rather than spots. So DOS seems to be a bit random to me. Though rapeseed oil seems prone, why it is worse in some cases than others, even when using the same essential oils from the same bottles, is a bit weird. Incidentally I gave one of the DOSed mint soaps to a work colleague - he couldn't get the off smell - and he loved it! I do have a couple of ancient 100% olive oil soaps I made when first starting soaping about 3 to 4 years ago. They are shrivelled up little rock hard lumps and are a bit brown round the edges but no actual DOS and no bad smell and are fine in use. The first batch of mint soaps are finishing off their curing in the shed where I can't smell them. I guess they'll end up in the bin eventually.
I made a test batch without Kaolin. I also realized that the eo is a blend. The blend that I have been using is 80% lavender eo and 20% cedar eo.
But in this batch I used just lavender eo, no blend and no kaolin. For some reason the tops of my soaps have been soft. I realized that I have been cut them sooner then the 24 hrs after the pour. This time I made sure that It was 28 hrs after the pour. The soap seems to be just as soft. I will make another batch and wait 48 hr to cut.
But in this batch I used just lavender eo, no blend and no kaolin. For some reason the tops of my soaps have been soft. I realized that I have been cut them sooner then the 24 hrs after the pour. This time I made sure that It was 28 hrs after the pour. The soap seems to be just as soft. I will make another batch and wait 48 hr to cut.
