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Hi y'all!

My son and I started out soap making when he had to put up an exhibit for his science fair in March. (We are sooo addicted now LOL!) One of the things he displayed was an eco-soap (pictured below) – made out of used cooking (sunflower) oil. It was coloured with blue mica and scented with peppermint. He was very inspired by soapmakers like Laura Kneib of Frog Soap, Noor Jehan in Malaysia and Delizia in Australia. He is now hoping to do a little more research on recycling oil and fatbergs and what not and to improve on this part of his exhibit for a bigger fair in September. He has a few questions:

1. After straining, what are some ways he can remove the odours from the oil? He has tried the following:
  • sprinkling a layer of flour on the surface and allowing that flour to settle to the bottom to catch the last of the impurities (this tip he got from Delizia)
  • soaking a block of charcoal in the oil
  • boiling ginger and/or lemongrass in the oil
2. Would soaps made from used cooking oil be safe for use on hands/the body? Many folks here would scoff at such a soap though, I just know it because when he mentioned this to an elder, she just grimaced and shuddered. He wrote to Delizia some time ago and she so kindly wrote back and said that such a soap (if well made) IS safe and that people just need to be educated. Having said that, we've used his eco-soap for general cleaning and washing out our kitchen cloths etc. and our hands have not suffered at all... not dry like when we use detergents. What are some things he needs to do to ensure that the soap is safe and good for bathing?

3. He is trying to improve the recipe as well... so far, we've only used the cooking oil and no others. Would it be better to add other oils like coconut? If we were to use soapee/soapcalc, do we just add the oil as "sunflower oil"? We used a recipe from Noor Jehan in Malaysia. She recycles used cooking oil ... I'm guessing that more palm oil is used for cooking in that part of the world, whereas here, people use ghee, sunflower and canola oil for cooking, so I'm wondering if we should tweak the recipe. (The blue soap took a while to unmould and cure.)

Sorry for this lengthy post! Can you tell that we are totally consumed by all things soap? haha...
 

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I didn’t even know you could use used cooking oil. What did you cook with it? Was it for frying? What does the soap smell like without the fragrance? Do you know how long the soap keeps for?

Off the top of my head, I can’t think why it wouldn’t be “safe” for personal cleaning, once you’ve removed all the little food particles, I would just not really be comfortable doing so; normally you make body soap with “superfatting” so the soap isn’t drying and you don’t risk extra lye, and the idea of rubbing used cooking oil on me doesn’t have much appeal…

Honestly, I think if you’re using so much oil that you have enough leftovers to make soap, you might be more “eco” using cooking recipes that don’t need so much extra oil 😅
Better use a liter of clean oil for soap and a couple tablespoons for cooking 😉
But as a school project that’s nice.

The idea of “eco” soap is great, but I think that’s going to depend a lot on where you are and what they grow/raise in your area. One thing that I find a bit unfortunate is the irony of palm oil; it’s in theory the most eco-friendly oil of them all, because it has the highest yield crops and it makes good everything, but because it’s so good and so efficient, it’s in EVERYTHING, there’s so much demand for it, so producers end up deforesting to grow it, and it only grows in areas that don’t have such great human rights track records.
But good on you, sunflower is the second best for yields 👍
https://ourworldindata.org/grapher/area-per-tonne-oil
I would recommend trying to formulate an eco soap with clean ingredients for personal consumption, and make the “eco” about which oils you use and from where 😊

Shea butter is another eco one, and much better for personal products. It comes from trees that take so long to grow that they are real “carbon sinks” and create nice little ecosystems around the trees. It’s apparently not possible to “deforest” for Shea because they are the forest!
 
Off the top of my head, I can’t think why it wouldn’t be “safe” for personal cleaning, once you’ve removed all the little food particles, I would just not really be comfortable doing so; normally you make body soap with “superfatting” so the soap isn’t drying and you don’t risk extra lye, and the idea of rubbing used cooking oil on me doesn’t have much appeal…

I totally get this... this is just what my MIL said LOL. She told me and my son – "PURE! USE ONLY PURE THINGS!" 🤣

I should explain why my son and I made these soaps. It started out as a part of his Chemistry of Clean exhibit for our homeschool co-op's Science Fest. He made a display talking about early soaps, saponification and also about ecology. He found out about fatbergs and how these clog up drains and sewers etc. He was very inspired by Laura Kneib of Frog Soap – she got local eateries to send their pots of used oil instead of dumping them – and also by people like Delizia of Delizia Naturally and Noor Jehan in Malaysia who do the same.

We actually don't use that much oil in our food ... we got some friends to donate their used oil. One of them had used her oil for frying prawns 🤣 and she was almost ashamed about the smell of her donation! We sieved, soaked in charcoal, boiled with ginger (could not get lemongrass), sieved again and it didn't smell like anything but oil ... no fishy, yucky smell. It was quite good after EOs. I don't know how long the soaps keep... this is something I need to learn!

I guess I should rethink the word "eco" 😊 I meant that the project was eco-friendly in that it helped reduce waste and pollution. You are totally right – eco ingredients are so much better and would certainly be more well-received! I really do want to get shea butter! I have not been able to find a good source locally and when I asked a few people, they were so tight lipped. Oh well.
 
Oh, and I just reread your last point, you should definitely be specific about which oils you use when calculating the lye; especially if you set a low superfat. This is also why cooking oils aren’t the best; it’s harder to make sure you know what they’re made of unless you use them straight from the bottle and the bottle is clearly labeled.

If you’re desperate, Shea is often sold in natural and “bio” stores, among the self care products; it’s just insanely priced.

I order it online 🤷‍♀️
 
Oh, and I just reread your last point, you should definitely be specific about which oils you use when calculating the lye; especially if you set a low superfat. This is also why cooking oils aren’t the best; it’s harder to make sure you know what they’re made of unless you use them straight from the bottle and the bottle is clearly labeled.

If you’re desperate, Shea is often sold in natural and “bio” stores, among the self care products; it’s just insanely priced.

I order it online 🤷‍♀️
Thanks so much! Yes... this used cooking oil business definitely isn't straightforward! One recipe online said something along the lines of: Unmould after a day. Use immediately – there is no need to cure because you are just using it for general cleaning. 😬 😱

I'll definitely continue looking for shea butter!

This subject comes up from time to time. Search the forum for "used cooking oil" (with the quotes) for more threads. For example:

Thread 'Reuse used cooking oil for soap' Reuse used cooking oil for soap

Thanks so much! I have one last jar of used cooking oil. Let's see if I can make something decent ;)
 
I personally would be concerned regarding the very high possibility of oils going rancid in soap much faster than usual after being repeatedly heated to high temperatures, and being done so in aluminum cookware (which I know for a fact is very commonly used in many countries which have a 'street food' culture, as well as in small cafes). I also know how people in many countries will 'economize' & reuse oils, as well as other substances, to eke out every last bit of money possible due to living in poverty. Western corporations - McDonalds etc - do this to maximize profit as well, and they are not living in poverty - just greedy sods. Most places that are cooking food for the public - in both Western & other countries - make a habit of reheating their oils at high temperatures. Many even reuse previous batches of oils day after day until they are absolutely unusable in their kitchens.

That aluminum contamination from aluminum cookware is a big issue. And if not using aluminum, there is also the risk of PFOA contamination from non-stick cookware. I have seen the cookware used in various countries I have lived & traveled in, so I would be very wary of this. Aluminum is still king in many places around the world due to its low cost / availability vs a better option like stainless steel.

Unless you know for a fact the type of cookware being used, as well as the number of times those oils were heated & reheated, not to mention whether they have been mixed with other oils of not, you are looking at turning out dodgy, substandard product.

I wouldn't touch any used oils like this for any of my products, including soap intended only for my personal use, for the above mentioned reasons.

Tell your son to look into bokashi composting as a way to be able to compost fats / oils / meat etc. I make at least 50 pounds of bokashi composting 'accelerator' every year & it is phenomenal stuff. In addition to allowing you to compost anything, including dairy, it also ferments your compost, boosting soil with beneficial microorganisms, and encourages earth worm population, mycelial growth and more. Most 'bokashi'-d compost is ready to be dug into the soil within 6 weeks.

Bokashi is not related to soap, but it could possibly be related to your son't science project in being able to find a use for 'fat bergs' and waste cooking oils.
 
I know most people in this forum use edible, clean fats for their soap making. We're lucky to be able to do that.

In times past and in some places today, soap was/is commonly made from low-cost or inedible fats -- fats collected from households and restaurants, textile manufacturing, meat packing, etc. Since soap is a low value product, the fats used for soap need to be cheap and plentiful. In the past, the more desirable fats went for use in candles, lamp oil, food products, etc.

There was a whole section of the soap making industry dedicated to reclaiming inedible fats -- deodorizing, bleaching, purifying, refining -- for use in soap. The process of reclaiming truly inedible fat isn't for the faint of heart.

Mildly rancid or oxidized fat -- say fats from a food fryer -- can be purified by washing with hot water to remove the water soluble ketones and aldehydes that give rancid fat that peculiar odor. This is the type of fat I'd suggest a student should work with first.

Since the free fatty acid content in the washed fat is likely to be high, this fat will react quickly with lye to form soap, so the washed fat is best used to make basic soap without fancy designs.

Here are a couple of my articles that touch on this subject --

Washing rancid fat: Rancidity and DOS | Soapy Stuff The info about washing fat is near the bottom of this article.

Salting-out soap: Salting-out soap | Soapy Stuff This is unrelated to rancid fat, but it describes how soap can be washed to clean it
 
I know most people in this forum use edible, clean fats for their soap making. We're lucky to be able to do that.

In times past and in some places today, soap was/is commonly made from low-cost or inedible fats -- fats collected from households and restaurants, textile manufacturing, meat packing, etc. Since soap is a low value product, the fats used for soap need to be cheap and plentiful. In the past, the more desirable fats went for use in candles, lamp oil, food products, etc.

There was a whole section of the soap making industry dedicated to reclaiming inedible fats -- deodorizing, bleaching, purifying, refining -- for use in soap. The process of reclaiming truly inedible fat isn't for the faint of heart.

Mildly rancid or oxidized fat -- say fats from a food fryer -- can be purified by washing with hot water to remove the water soluble ketones and aldehydes that give rancid fat that peculiar odor. This is the type of fat I'd suggest a student should work with first.

Since the free fatty acid content in the washed fat is likely to be high, this fat will react quickly with lye to form soap, so the washed fat is best used to make basic soap without fancy designs.

Here are a couple of my articles that touch on this subject --

Washing rancid fat: Rancidity and DOS | Soapy Stuff The info about washing fat is near the bottom of this article.

Salting-out soap: Salting-out soap | Soapy Stuff This is unrelated to rancid fat, but it describes how soap can be washed to clean it
@DeeAnn, I just want to thank you for all the "science stuff" you provide. You help us understand the whole soap making process!
 
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I personally would be concerned regarding the very high possibility of oils going rancid in soap much faster than usual after being repeatedly heated to high temperatures, and being done so in aluminum cookware (which I know for a fact is very commonly used in many countries which have a 'street food' culture, as well as in small cafes). I also know how people in many countries will 'economize' & reuse oils, as well as other substances, to eke out every last bit of money possible due to living in poverty. Western corporations - McDonalds etc - do this to maximize profit as well, and they are not living in poverty - just greedy sods. Most places that are cooking food for the public - in both Western & other countries - make a habit of reheating their oils at high temperatures. Many even reuse previous batches of oils day after day until they are absolutely unusable in their kitchens.

That aluminum contamination from aluminum cookware is a big issue. And if not using aluminum, there is also the risk of PFOA contamination from non-stick cookware. I have seen the cookware used in various countries I have lived & traveled in, so I would be very wary of this. Aluminum is still king in many places around the world due to its low cost / availability vs a better option like stainless steel.

Unless you know for a fact the type of cookware being used, as well as the number of times those oils were heated & reheated, not to mention whether they have been mixed with other oils of not, you are looking at turning out dodgy, substandard product.

I wouldn't touch any used oils like this for any of my products, including soap intended only for my personal use, for the above mentioned reasons.

Tell your son to look into bokashi composting as a way to be able to compost fats / oils / meat etc. I make at least 50 pounds of bokashi composting 'accelerator' every year & it is phenomenal stuff. In addition to allowing you to compost anything, including dairy, it also ferments your compost, boosting soil with beneficial microorganisms, and encourages earth worm population, mycelial growth and more. Most 'bokashi'-d compost is ready to be dug into the soil within 6 weeks.

Bokashi is not related to soap, but it could possibly be related to your son't science project in being able to find a use for 'fat bergs' and waste cooking oils.

I've been away from home for a few months and have only just logged back in here. Thank you so much for the tip about bokashi composting – my MIL is into this sort of thing, so I'll tell her about this!

I know most people in this forum use edible, clean fats for their soap making. We're lucky to be able to do that.

In times past and in some places today, soap was/is commonly made from low-cost or inedible fats -- fats collected from households and restaurants, textile manufacturing, meat packing, etc. Since soap is a low value product, the fats used for soap need to be cheap and plentiful. In the past, the more desirable fats went for use in candles, lamp oil, food products, etc.

There was a whole section of the soap making industry dedicated to reclaiming inedible fats -- deodorizing, bleaching, purifying, refining -- for use in soap. The process of reclaiming truly inedible fat isn't for the faint of heart.

Mildly rancid or oxidized fat -- say fats from a food fryer -- can be purified by washing with hot water to remove the water soluble ketones and aldehydes that give rancid fat that peculiar odor. This is the type of fat I'd suggest a student should work with first.

Since the free fatty acid content in the washed fat is likely to be high, this fat will react quickly with lye to form soap, so the washed fat is best used to make basic soap without fancy designs.

Here are a couple of my articles that touch on this subject --

Washing rancid fat: Rancidity and DOS | Soapy Stuff The info about washing fat is near the bottom of this article.

Salting-out soap: Salting-out soap | Soapy Stuff This is unrelated to rancid fat, but it describes how soap can be washed to clean it
Thanks ever so much for this... fascinating business, this! Sorry I took a while to reply... I've been away. I could not open your articles :( For some reason, server could not be found.
 
Wow, this is the first time I've come across this thread. I LOVE that you're making soap from used cooking oil! I would take @DeeAnna's advice and wash the oil first. Be sure you know what type of oil you're getting (I assume from a restaurant or something?), and use a calculator.

I would even suggest attempting to get oils from more than one place for a bit of variety in your soap.

I personally would not have an issue with soap made this way. The lye will pretty much kill anything left in the oil.

Maybe put a positive spin on how you describe the oil you're using. "Recycled Cooking Oil" or "Upcycled Cooking Oil"
 
@Chaiat5 I returned to the US a year ago after a 6 year stint in India (in Kerala, so not that close to you in Islamabad!) But I used rice bran oil at times for soap and lotions, I used to get it off of Amazon for less than 1000 INR for 5 liters. I also used rice bran and sunflower oils for lotions/creams, and refined mango and kokum butters which, while expensive, were cheaper than some others and also smelled better - I was really disappointed that the moringa oil and butter I ordered smelled pretty funky, I ended up not using them because I didn't think I could cover up the smell with EOs or FOs.

This is a three year old thread, but there are a lot of Indian suppliers listed in this thread, maybe they have some items that are harder to find in Pakistan? Soap making ingredients suppliers in India. Not really helpful for eco-soap, but for your own soapmaking adventures :)
 
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It's back :) hope all is well with @DeeAnna

Thanks, everyone, for your concern! I really appreciate this.

My internet service provider had a problem that affected a lot of the domains they support, including the website with my "Soapy Stuff" articles. The website was unavailable from Friday through Monday when the problem got fixed.

Needless to say, I was pretty frustrated about the outage, but all is well now.
 
Wow, this is the first time I've come across this thread. I LOVE that you're making soap from used cooking oil! I would take @DeeAnna's advice and wash the oil first. Be sure you know what type of oil you're getting (I assume from a restaurant or something?), and use a calculator.

I would even suggest attempting to get oils from more than one place for a bit of variety in your soap.

I personally would not have an issue with soap made this way. The lye will pretty much kill anything left in the oil.

Maybe put a positive spin on how you describe the oil you're using. "Recycled Cooking Oil" or "Upcycled Cooking Oil"

Thank you for the encouragement :) I'd love to be able to create something worthy like the ones produced by Frog Soap and Delizia Naturally ... they're my inspiration! I love the idea of making something so pretty and useful out of waste!
 

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