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How to Extend the Shelf Life of Base Oils for Soapmaking

A couple months ago, I was asked how to extend the shelf life of base oils for soapmaking. Since I¬†realized I haven’t ever written about it here on Modern Soapmaking, I made a mental note to do a blog post in the future. Here we are!

How to Extend the Shelf Life of Base Oils for Soapmaking
How to Extend the Shelf Life of Base Oils for Soapmaking

Purchase Quality Base Oils in the First Place

It’s super important to purchase¬†your base oils from reputable suppliers. One of the first questions I ask soapmakers when they have issues with their soaps developing DOS (Dreaded Orange Spots) or not turning out right is, “Where did you buy your base oils?

A lot of oils found at grocery stores are adulterated or old (and technically, rancid.) Anne-Marie and her team over at Soap Queen did a test soapmaking session of a variety of olive oils bought in a grocery store, and the results speak for themselves.

When it comes to oils being old or rancid when you buy them, it makes sense really. From experience in the world of grocery, I can tell you that not a lot of people purchase¬†specialty cooking oils¬†often. A lot of those oils sit on the grocery store shelves until the expiration date, and then they’re thrown away by the store. When oils are exposed to tons¬†of light and temperature changes, it speeds up the oxidation process, which means the shelf life of those base oils is shorter from the get-go.

If an oil is adulterated, your fatty acid profile may¬†not be what they should be for the oils¬†that you are using. If that’s the case, you may end up with lye heavy soap or an extra superfat, as the saponification values are not properly calculated.

Don’t waste your money on base oils found in grocery stores – usually, it’s much cheaper to purchase oils from a soapmaking supplier rather than the grocery store anyways! (Small exception: I haven’t had issues with oils purchased from local cash n’ carry, Restaurant Depot, Costco, or Sam’s Club. I think it’s because they are bulk purchasers, who tend to supply restaurants rather than consumers.)

Soaper’s Choice is the my go-to supplier for base oils online, but the smallest size they carry is¬†a gallon (roughly¬†7 pounds.) If that’s too much oil for you in one go, I recommend trying general soapmaking supply vendors, such as Bramble Berry, Wholesale Supplies Plus, Nature’s Garden, etc.

Store Your Base Oils Properly

To maximize the shelf life of your base oils, you should always store them in a cool, dry, and dark place, away from heat and direct sunlight. If a base oil is especially fragile (those oils with a shorter shelf life), it’s best to keep them refrigerated, if possible.

You should keep all of your base oil containers closed tightly, and only open them when you need to. If a base oil is in a container with a lot of headspace (empty space in the container containing oxygen), you may want to consider transferring it to a smaller container to reduce the amount of oxygen exposure.

Extend the Shelf Life of Base Oils With an Antioxidant

Using an antioxidant in your base oils will help prolong the shelf life of the oil by slowing the oxidation process. Kevin Dunn wrote a white paper for the Handcrafted Soap & Cosmetics Guild back in 2005 about the effectiveness of various antioxidants and additives.

My personal go-to antioxidant is Rosemary Oleoresin Extract (commonly referred to as ROE.) I add it to my base oils as soon as I crack the seal or open the container. Some soapmakers wait to add ROE to their base oils when they are making soap, which can help prevent DOS, but it makes much more sense to me to add it as soon as possible.

Rosemary Oleoresin Extract is available with varying levels of carnosic acid (the large contributor to its effectiveness.) I personally¬†purchase ROE with a 7% carnosic acid content, as it’s highly effective and has a much lower usage rate. The usage rate of ROE will depend on the carnosic acid content, but it’s typically extremely low at 0.5% or less.

Rosemary Oleoresin Extract is extremely thick and can be difficult to add to your base oils. To add ROE to a fresh bottle of oil, I weigh the necessary amount of Rosemary Oleoresin Extract in a clean measuring container, and then add a small amount (a couple of ounces) of oil to it. After mixing the ROE into the small portion of oil, I add the oil with ROE added, back to the main container, close the lid, and shake it up.

Side Note: If you choose to use an antioxidant or additive, please remember to include it on your product labels!

How do you know when your base oils have gone bad?

Base oils that have gone rancid typically smell bad, anywhere between stinky feet and rotten eggs. It’s quite obvious when a base oil has past its expiration date, I promise! Many suppliers will also list a shelf life and/or expiration date on the base oils they sell. If you aren’t sure, contact your supplier with the oil’s purchase date and/or batch number, and ask for a¬†verification of the expiration date.

DOS (Dreaded Orange Spots)
DOS (Dreaded Orange Spots)

If any of your soaps develop DOS, which are yellow to orange spots indicating an issue with oxidative rancidity, you may have a rancid base oil on your hands. While DOS is usually caused by rancid oils, it can also be caused by high humidity or heat exposure to the soap itself, using tap water, and/or storing it with older soaps (among other issues!)

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18 Responses

  1. Thanks for the tips. I live in Florida and am constantly at war with DOS due to the humidity and heat. I use a refrigerator for my oils. I also use vitamin e and ROE. I never thought of adding it to the oil once I pop the top. I’ll try that. Thanks again.

    1. No problem! As far as I’ve seen, Vitamin E is not a strong enough antioxidant to do much good, plus it’s so expensive! Whereas ROE is more cost effective and (as far as I’m aware) is the strongest effective antioxidant to use for the “natural ingredients” label appeal. Other additives are more effective, but not friendly for most soapmakers’ target markets.

  2. Good suggestions. I just purchased ROE since I’ve been plagued with DOS. Frustrating! I follow all the other advice — buy from trusted vendors, buy what I will use in a decent time frame (6 months is my goal), keep in a cool-ish spot. I’ve even been taking over the refrigerator for my oils and hydrosols! I checked all my oils for dates and smell and found many of the oils that smelled rancid (which I promptly threw out) were from the same vendor. Unfortunately, it is a well-known, well-established site. I won’t buy from them anymore.

    Once I receive a bottle of oil, I mark it on the label in red when it was received and what the “use by” date is. Once it’s opened, I add the ROE and note that on the label as well. Hopefully my problems with DOS will be resolved.

  3. What type of olive oil do you recommend? I have been buying olive oil from Costco and not the virgin. Where do you buy yours from? I have looked at some of the suppliers you recommended but they list so many types of olive oil and I don’t know which to pick! LOL.
    Thanks so much……just love your blog.

  4. Hi Kenna,
    As a newbie soap maker, i have found your blog so helpful! Thank you! But i have a specific question about using ROE. I read the article you attached, which recommended a ROE percentage of 0.1%. And you mentioned a percentage up to 0.5%. But the ROE comes in different strengths of carcinic acid…4%, 6%, etc. So, if i want my total batch to have an ROE percentage of 0.1%, how do i measure that? Do i measure the ROE as just 0.1% of total volume of the batch, no matter what the percentage of carcinic acid? Or do i have to calculate for some standard level of carcinic acid? I’m sorry if I’m making this too hard! But i hope my question makes sense! I just want the antioxidant level to be effective. Thanks in advance for the help!

  5. Hi! Great info! I just want to give a another reason for orange spots, if some people have experienced DOS but couldn’t pinpoint the reason. I have been soap crafting for over six and a half years. My lye discount is 5%. I don’t add vitamin E to my soaping oils or any other antioxidant during soaping nor at the time of bottle unsealing. I also love and mainly order from Soaper’s Choice (a gallon is 8 pounds/128 oz, SC supplies in 7lb/112oz jugs). BTW in most cases Soaper’s Choice is more affordable than WholesaleSuppliesPlus, but WSP’S gallon buckets are easier to get solid oils out of. But I still go with SC jugs. Anyway! Lol. So in the six and a half years I’ve been crafting I’ve only experienced orange spots in a very small number of small batches, and it’s my cue to toss my stick blender for a new one. The last time was just a couple months ago when I made three batches of soap, the first three after a few months of zero soapmaking- we had just moved and I didn’t have the time. About 3 weeks into the drying phase I noticed the dang DOS. I smelled all my jugs and all smelled fine. I checked my stick blender. I’m thinking I ran it through the dishwasher with all my tools after we had settled in after our move, but it might not have been enough since it had laid months unused. Regularly, I clean it after each batch, but after losing that much soap (all made the same day back to back, same oil formula do no blender washing in between) I decided to just toss it again and get a new one. I think I’ve gone through 4 stick blenders in 6.5 years. I made the next few batches the same way, with the same oils from half empty SC jugs sitting for months unused, but this time with a new stick blender, and no DOS. I still have some 3 month old soaps from that batch of “new blender and ‘old’ oils”, and no DOS, so it wasn’t the bulk oils. Check your blender for oil residue (if you use one). You’d think it wouldn’t be enough to ruin a whole batch but apparently it can. I hand wash my sticker blender attachment (pointy object with a soapy paper towel and wipe the rubber seal behind most stick blender blades), then turn it on in baking soda/dish soap solution in really hot water, run it through the dishwasher, and in heat dry, and even after that the moment it’s time to blend another batch say a day later, I run it again in baking soda/soap/hot water once again to try to release any possible leftover oil residue before sticking it in the batch lol. I hate DOS. It doesn’t ruin the soap’s cleansing properties, it’s just unsightly when it comes to selling soaps. We just don’t want customers having the notion that by selling soaps with known orange spots it might be because the soaper was willingly using rancid oils. And the customer doesn’t want to hear, ‘it’s just a little rancid oil, but it was just my blender! No biggie your soap will still lather!’ Lol

  6. I have bought olive oil which is going to expire in 2 months. Can I still use it to make soap ( 80% olive oil and 20% coconut oil)? Normally I will cure the soap for 10 weeks, that means when the soap is ready to use, the olive oil inside the soap has expired…. If I keep the soap properly in cool dry place, can it still be used, and for how long ? And, if I add ROE will it help to further extend the shelf life?

    1. It varies dependent on the shelf life of the oils involved and the formula itself. For instance, if a formula contains a lot of linoleic and linolenic acid, it will have a much shorter shelf life than a formula that contains a ton of lauric acid. This article talks a bit about fatty acids: https://www.modernsoapmaking.com/the-most-popular-fatty-acid-profiles-in-soapmaking/ The further down in the list you go in that article, the shorter the shelf life (except ricinoleic). Most stable and quality liquid soap recipes should see a shelf life of 6 months to 2 years. If you will be selling your products, we highly recommend doing the research and development to reach a minimum one-year shelf life.

  7. Hi,

    Just to clarify, what percentage of ROE do you add to your individual oils when you first bring them home and pop them open? And does this mean you don’t need to include an antioxidant again when you’re actually making the soap? Thanks for letting me know ūüôā

    1. Rachelle,
      The usage rate of ROE will depend on the carnosic acid content, but it’s typically extremely low at 0.5% or less. Your supplier should be able to tell you both the carnosic acid content (we like 7%) and the usage rate. No additional antioxidant has to to be added.

  8. question about oils, When you use oils like Avocado and Sweet Almond oil. Do they keep all of the properties that’s good for the skin when made into a soap? All the benefits they have for skin, or would it be best to leave expensive oils like that out? Does soap really benefit from all the attributes in each specific oil… let me know thanks. and i”m sure lots of others might find this question interesting as well.

    1. Hey, Chris,
      The jury is still our on what benefits of specific oils survive saponification…and, if they do, how much that really matters in a wash off product. We tend to formulate to hit the fatty acid profile for the characteristics we want rather than trying to cram luxury oils into our soap recipes.

  9. Hi Kenna,

    Thanks for the wonderful article. Definitely helps!

    If by adding ROE can help extending the shelf life, how many more months can you get out of an oil?

    Let’s say if a particular oil will expiry in 18mths, by adding ROE once opened, do you extend the shelf life for another 6mths? 12mths? or double the shelf life? Assuming it is stored inside a fridge once opened.

    What if you are adding ROE to a short shelf life oil that only has 6mths shelf life, like avocado oil? How many months can you extend it?

    I usually throw away the oil once it reaches expiry date. Now I am considering to add ROE to all my carrier oils but I am not sure how to adjust the expiry date (like how many more months I should extend it).


  10. I’m so glad I found your article! I’ll be ordering an antioxidant today now that I’ve seen the result of a couple of soap batches.

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