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Troubleshooting herbal oils


Things that can go wrong when making herbal oils.

  • The first is, your herbal oil can rot. This happens rather too often if you make oils with the "let sit on the windowsill for weeks" method, especially if you use fresh herbs.

You can make it happen less often if you let the herb dry to half its fresh weight first: then, only about 1 batch in 20 will rot on you. With fully fresh herb, about 1 batch in 4 will rot.

Making oils on a windowsill (I haven't for years, because they rot, and go moldy, and even go rancid): SJW oil hasn't gone rotten on me. Calendula flower oil has. Yech! for the smell. Gak. Urk.

  • The second is, your herbal oil (and therefore, salve) can grow mold. This happens if you use fresh herbs without getting rid of all the water, or if you use not-quite-fully-dried herbs.

Only one salve batch has gone moldy on me. This was when I was in a hurry and proclaimed the calendula flowers dry. They weren't quite, and I knew it, but I thought I could get away with it.

What a waste of herb, oil, and beeswax. And time and bother, of course. So don't, eh? Make sure your oil doesn't contain any water at all. Impossible with a fresh herb oil, you say? Let your oil sit for 7 days, then clear the oil (no water) off the bottom muck (all the water).

And make sure no water gets in the oil while you're making your oil into a salve, too.

  • The third is, your herbal oil (and salve) can go rancid. Or, your herbal oil will go rancid, one day. You can't stop it, but you can slow things down.

Vitamin E retards rancidity. It's soluble in oil. Vitamin C would also retard rancidity (it's also a strong antioxidant), but it's soluble in water, so can't be used in oils.

Most cold-pressed oils contain loads of vitamin E, but to make really sure you can add 10 ml (1/10 dl) per 1000 ml (1 l) oil, if you so like. Note, vitamin E out of a bottle is a sticky mess. It doesn't smell (small favors, eh?) but bleh! for cleaning anything that vitamin E got onto.

Infused oil of St. John's wort (Hypericum) retards rancidity for years - no SJW oil has gone rancid on me yet. SJW won't stop mold, though: long long ago, back when I still made oils on the windowsill, any SJW herb which stuck out of the oil would grow mold.
Balsam poplar buds ("balm of gilead buds") retard rancidity very nicely, but your oil (or salve) will smell of balm of gilead buds. You don't always want that.

  • When you make fresh herb oils you might find that there's something algaelike floating around in your oil, a few months after you decanted the infused oil off the bottom muck. This strange gel is not dangerous, is not something growing in there, is not toxic. A herbalist who is also a biochemist, and who had seen them too, could not culture anything from them. He found that they're precipitates that come out of the oil. They dissolve back into the oil when heated, so use away.

I don't add essential oils (EOs) in my herbal oils (or salves), but you can add 1 drop per 30 ml (1 oz) salve, if you so like. This will stop mold and retard rancidity. Do bear in mind that lots of people are allergic or sensitive to essential oils. They aren't allergic or sensitive to my salves - partly because I don't use EOs in them, partly because I use organically grown or wildcrafted herbs (... my own, mostly), certified organic oils, and beeswax from a certified organic bee keeper.

Next up: troubleshooting herbal salves.


re: Vitamin E retards rancidity. It’s soluble in oil. Vitamin C would also retard rancidity (it’s also a strong antioxidant), but it’s soluble in water, so can’t be used in oils.

There is a fat/oil soluble Vitamin C, ascorbyl palmitate, made popular by Dr Perricone, (The Wrinkle Cure), etc. It is used as a preservative in some commercial "natural" lotions and skin care products and is also sold as a vitamin by several 'natural' lines, though I have found references that state it is synthetic. I have not tried it in a salve though it might be worth a try.

I just started making an herbal oil with olive oil (extra virgin) and thai basil. It sat three days in the sun on my kitchen counter and then it got cloudy. Help?

You made a fresh herb oil, using the "let sit on a sunny windowsill for ages" method? Wait for a while longer and it'll either start to bubble or to grow snotty, and it'll start to smell. Yeuch.

Do your herbal oils with the waterbath method, you'll lose fewer batches that way.