DOS, Finally

[BrewerGeorge]

I make a bar with tea tree and peppermint, plus lots of charcoal. I use it only for my face so a one kilogram batch lasts a very long time - probably two months plus for each of the eight bars. I grabbed the last bar of the last batch yesterday which is, at a guess without checking my notes, about 20 months old.

It was covered with ash yesterday, but I just rubbed it off pretty well and wet it as I usually do to get past that "first use" phenomenon, while actually washing with the last sliver of the previous bar. I didn't notice anything untoward past the ash and the strong gray-black of the soap itself.

This morning was the first I actually planned to use it, but I noticed lots of definite warmer-colored spots. They're hard to see on the blackish background, but they're definitely there. DOS, for sure. It doesn't smell rancid, but the tea tree is a high olfactory bar to overcome. I'll trim on it tonight and see if it's just surface effects, but given the age and the high incidence of spots (probably covering a quarter of the surface) I don't have high hopes.

I have no real question, just commiserating and sharing the data point. This was 50% Great Value tallow shortening, 20% olive, 20% coconut, 5% avocado, and 5% castor. It was protected with both BHA (in the shortening) and citric acid and stored well, but still developed DOS in under two years.

I told myself when I took the second-to-last bar that it was time to make another batch. Alas, I procrastinated and do not have another one ready to go. Looks like I'll be poaching one of my mother's tea tree bars (no charcoal or peppermint) in the meantime.

 

[Lin19687]

Oh I wanna see a pic. So hard to see DOS on such a dark soap I agree.

 

[Alfa_Lazcares]

Just a while ago i was wondering how visible DOS spots would be on a darker colored soap, i would also like to see a pic.

 

[DeeAnna]

Welcome to the club, BG.

PS: EDTA in this batch? Or no?

 

[Obsidian]

Congratulations??!!

 

[BrewerGeorge]

Welcome to the club, BG.

PS: EDTA in this batch? Or no?

No I settled on sodium citrate because it has dual purpose for cooking as well.

Here's a pic. It's lighter in the pic than it was on the phone when I took it. You can still see the brownish spots.

And before anybody says anything: I know you're not supposed to use soap on cast iron, but the best light is above my stove and this way you all can't see the crumbs under the burner grate.

After taking the picture, I started carving on it. I had to remove about a third of it before all the spots were gone and it stopped whiffing of the lid of an old canola bottle.

I tossed it onto the kitchen sink pile of scraps for hand washing.

 

[SaltedFig]

Not sure whether this is of any use to you, but I find tea tree to be almost as bad as lavender for shelf life once it's opened, with the additional problem that tea tree oil reacts with plastic quite quickly (to the detriment of both the tea tree oil and the plastic).

 

[psfred]

Unless it's revolting to smell, it's fine to use it as soap. Maybe not on your face if the odor is pronounced, though.

I'm using up some of my early soaps that got DOS -- it's on the surface to start with, and regular use will remove it. Mine all seems to be associated with a batch of lard I used, it's only in those soaps, and in all but one case, only on the interior surfaces. The outside of the soap is fine, even the side that was against the end of the mold, but cut surfaces away from the outside get yellow. Almost as if the part of the soap exposed to less oxygen when hot (all hot process soaps) went bad first.

You are in great shape if it took two years for spots to show up!

Future soap at my house will get the full treatment: EDTA, citrate, and BHT.

 

[BrewerGeorge]

Not sure whether this is of any use to you, but I find tea tree to be almost as bad as lavender for shelf life once it's opened, with the additional problem that tea tree oil reacts with plastic quite quickly (to the detriment of both the tea tree oil and the plastic).

Nice to know.

I love lavender so much, but dislike spoiled lavender more. I've been using lavender EO drops in my CPAP machine for a couple of years and old lavender is revolting. It's weird because it's objectively not nearly as bad as some other smells, but as compared to good lavender the difference is worse than almost anything.

 

[earlene]

Yes, nice to know. I just wrapped & labeled the salt soaps I fragranced with tea tree oil (made May 1st). They are tucked away in a dark place now so I hope that helps, but now I have to remember to check on them a bit now and then for DOS. I wonder if the high salt content will be a deterrent? I can only hope.

I also love lavender, BG. So far so good with not getting DOS in my lavender soaps. I think I've been lucky with that.

 

[shunt2011]

I've not experienced any DOS in my Tea Tree soap. I have some a couple years old (a blend of Tea Tree and Orange). I also recently made a charcoal soap with Tea Tree, Peppermint & Lavender. Will watch that one to see if it goes funky. Always keep a bar to monitor.

 

[NsMar42111]

Me and lavender do not get along...welcome to the DOS club. I'd say we have cookies, but they're just soap!

 

[DeeAnna]

I've had odd results using peppermint and/or lavender EOs in soap. Enough so that I'm now leery of using either in soap. Sometimes they don't trigger rancidity, but when they do, the fail is impressive. It's sad, because I really like a blend of lavender and rosemary with a titch of mint.

 

[soapmaker]

I've had odd results using peppermint and/or lavender EOs in soap. Enough so that I'm now leery of using either in soap. Sometimes they don't trigger rancidity, but when they do, the fail is impressive. It's sad, because I really like a blend of lavender and rosemary with a titch of mint.

So strange but this is exactly my experience. Long ago I learned that any soap I make with Lavender or Peppermint needs ROE to prevent DOS. And that's all I use. Fixed the problem for me. My notes say in bold print: Anything with lavender or mint needs ROE! I would not know what to do without those two e.o.s I never had a problem with Tea Tree.

 

[maya]

Lavender for me does it every flippen time. And it seems fruit flats (the boxes that fruit comes in from the grocery store.)

 

[Dean]

I think my soaps have DOS too <eyes averted in shame>. They are fine when drying but as soon as I use them after about a 6 week cure, they develop dark spots. Not sure why since it is not humid where I live, super-fat is low, my oils are fresh and refrigerated and lins are below 15%.

 

[DeeAnna]

A used bar of soap is more prone to becoming rancid than the same bar that's not been used. This is especially true if you use the soap for awhile to wash extra greasy-dirty hands, then let it sit unused for a week or three. Often the entire bar will get a definite yellowish tinge after awhile.

If I remember right, the Lather Lovers soap swap done a few years ago had this problem -- some of the bars that had been used for testing the lather turned rancid-ish, but bars not tested were not as affected.

I think it's probably metal particles, general dirt, maybe skin particles, and other contaminants that rub off your hands onto the soap that trigger the rancidity. Using the soap regularly prevents this kind of rancidity from happening -- I only see this in bars of soap that have been used and then left untouched for some time.

 

[earlene]

Lavender for me does it every flippen time. And it seems fruit flats (the boxes that fruit comes in from the grocery store.)

Wow, really? Your soaps get DOS when you store them in fruit flats? I need to take a look at that! I have been using cut box bottoms of whatever I can get for curing my soaps since I started soaping. Not sure if any are fruit flats, but that is something to take a look at, for sure. I do line them with paper first, then put a little plastic mesh mat on the paper to lift the soaps a bit for help with air-flow. But that doesn't mean the soaps don't touch the cardboard at some point or another. I wonder...

 

[psfred]

Sunlight also catalyzes DOS, starting on the edges. Soap left on a sunny window will start to turn yellow. Doesn't stink, but it does yellow.

Water on the surface of the soap might speed up chemical reactions too by dissolving things.

 

[CaraBou]

Nooooo, people! It can't be true! I've managed to stretch my most divine lavender for about 4 years, using it sparingly all along the way. There's just an ounce or so left out of 16. I just checked it again and my eyes still roll straight through my skull in bliss. Say it won't go away, pleazzzzze, that supplier is no longer in biz!