Made soap from used cooking oils....something went wrong :D

[Piero]

Hello people,

We wanted to play a little bit and tried to make soap from used cooking oils, 100% rapeseed oil. I went to a canteen and they gave me 2 liters to play with. Always wanted to see if we could make soap from upcycling waste cooking oils
We filtered with very tight nets/cloths and then saw on a few YouTube videos that they also suggested putting flour and let it sink since it would take away a lot of impurities. We did that as well

Today, I went to try it and bubbles are ok, could be more lathering and it cleans ok as well. However, when washing it does leave your hands with a sort of layer and smaller smooshy pieces of soap. I have attached a photo so you can see what I mean.

Since this has never happened before, I have no idea what went "wrong" and what we can do to fix it.
Any ideas?

This is the recipe I used. Should I change the water: Lye ratio?

Thank you very much in advance

 

[artemis]

When did you make the soap?

 

[Piero]

When did you make the soap?

May 30th.

 

[AliOop]

Rapeseed oil on it's own won't produce much lather, especially after such a short cure. If you added 20% coconut oil, it would lather better and be a nicer soap overall.

I also suggest "cleaning" the used oil like one cleans tallow or lard after rendering. This involves putting a small layer of water on the bottom of the pan, tossing in some salt, and then adding the oils. Bringing it to a slow simmer, and the impurities will rise to the top as dirty foam, which you can skim off. Keep doing this until there is no more foam. The salt also helps with drawing out some of the smell.

 

[Piero]

Rapeseed oil on it's own won't produce much lather, especially after such a short cure. If you added 20% coconut oil, it would lather better and be a nicer soap overall.

The idea was to make a 100% soap from upcycled used cooking oils. We can try it though, thanks for the suggestion

 

[AliOop]

The idea was to make a 100% soap from upcycled used cooking oils. We can try it though, thanks for the suggestion

If you want to stick with 100% recycled oils, then consider using dual lye, or dissolving some form of sugar in the water (before adding the lye) to increase solubility. Then the soap will lather better.

Also, most single-oil soaps need a fairly long cure before they become nice(r) to use. But that's a problem with your particular soap, since by the time it cures, it might go rancid based on the high linoleic/linolenic fatty acid content, and the fact that the oils were likely rancid, or at least, quite degraded when you received them.

 

[Piero]

If you want to stick with 100% recycled oils, then consider using dual lye, or dissolving some form of sugar in the water (before adding the lye) to increase solubility. Then the soap will lather better.

Also, most single-oil soaps need a fairly long cure before they become nice(r) to use. But that's a problem with your particular soap, since by the time it cures, it might go rancid based on the high linoleic/linolenic fatty acid content, and the fact that the oils were likely rancid, or at least, quite degraded when you received them.

Ok, was not aware of the potential rancidity of the soap. Thanks for the input

So if I wait longer the smooshy effect that it does today it could go away?

 

[KiwiMoose]

In addition - you have used way too much water, which will also contribute to 'smooshiness'. Change the settings to 'lye concentration', and then 33% (assuming you are using the cold process method. I would probably also reduce the superfat to 2 or 3%, since you don't want to much superfat with this oil.

 

[Piero]

If you want to stick with 100% recycled oils, then consider using dual lye, or dissolving some form of sugar in the water (before adding the lye) to increase solubility. Then the soap will lather better.

Ok, this is some really cool insight.
Should I stick with a certain percentage of sugar based on the lye? I have never done it

In addition - you have used way too much water, which will also contribute to 'smooshiness'. Change the settings to 'lye concentration', and then 33% (assuming you are using the cold process method. I would probably also reduce the superfat to 2 or 3%, since you don't want to much superfat with this oil.

Ok, will try it tomorrow. Thanks

 

[Ford]

Hi, the oil has been subjected. To some very high temps already. Shelf life has been compromised. Don't expect a too much from it. I used it at 50%. Trying to use it in a recipe. But still make a reasonable bar. I filtered mine thru several layers of cheese cloth. But did not salt it out. As @AliOop suggested. And went from there.
I posted pics and the recipe I used. In the pictures gallery. A while ago. Good luck.

 

[Zuleika]

You could find different types of waste oil (if possible) and mix them for a more balanced recipe.

Since this has never happened before, I have no idea what went "wrong" and what we can do to fix it.

I take it you previously made a canola soap and it turned out different from this batch?

 

[Piero]

You could find different types of waste oil (if possible) and mix them for a more balanced recipe.

That would also be possible. Most of the places here in Odense, Denmark, are using rapeseed for their frying and I have not seen or heard anyone using other oils for frying. I will keep on looking.

I take it you previously made a canola soap and it turned out different from this batch?

I never made soap with 100% rapeseed oil, always mixed. We did make a 100% olive oil soap and it did have somehow a similar ending know thinking about it. Not as much as this one though, I have noticed this loses it's consistency more in the hands and "sticks" to them.

 

[AliOop]

Ok, this is some really cool insight.
Should I stick with a certain percentage of sugar based on the lye? I have never done it

The typical sugar usage rate is anywhere from 1% to 3% of the total oil weight. Just dissolve it in some water first, before you add the NaOH to it.

 

[soapface]

I've always wanted to try this, so am following closely. I have about 4 litres of used rapeseed oil from my deep fryer that are on its last legs I think.

I was considering trying this to clean it: https://www.seriouseats.com/clean-cooking-oil-with-gelatin-technique

Has anyone tried this before?

Also @Piero what did your soap smell like?

 

[AliOop]

I've always wanted to try this, so am following closely. I have about 4 litres of used rapeseed oil from my deep fryer that are on its last legs I think.

I was considering trying this to clean it: https://www.seriouseats.com/clean-cooking-oil-with-gelatin-technique

Has anyone tried this before?

That sounds really cool! Let us know if you try it!

ETA: I am guessing this works only with liquid oils, and not hard fats such as tallow or lard.

 

[justsomeguy]

That sounds really cool! Let us know if you try it!

ETA: I am guessing this works only with liquid oils, and not hard fats such as tallow or lard.

What I did with my tallow (brisket trimmings rendered in the smoker with the brisket) was put it in a mason jar, leave about 1.5 inches free, as about an inch of water. Put the lid on tight, turn it upside down and pop it in the fridge. After about 2 hours the the tallow hardens and the crispy bits are at the top

 

[AliOop]

What I did with my tallow (brisket trimmings rendered in the smoker with the brisket) was put it in a mason jar, leave about 1.5 inches free, as about an inch of water. Put the lid on tight, turn it upside down and pop it in the fridge. After about 2 hours the the tallow hardens and the crispy bits are at the top

I do something similar for the first clean, but I prefer a wider and more shallow container for ease of removing the disc of fat.

 

[Cindy D.]

View attachment 78217

Thank you very much in advance

If you look at the predicted qualities of the soap recipe in the lower left. Under hardness your soap is predicted to have a hardness of 5, normal soap has a hardness of 29 to 54. Try several different oils and see how the numbers change, it can help you understand what is happening and how you can improve you soaps.

 

[LidiaG]

Hello people,

We wanted to play a little bit and tried to make soap from used cooking oils, 100% rapeseed oil. I went to a canteen and they gave me 2 liters to play with. Always wanted to see if we could make soap from upcycling waste cooking oils

Hi @Piero

Good for you for repurposing that oil!
I have been making soap with used cooking oils as well. I tried for personal use and I did not like it too much because of the quality of the used oil. But I had great success to make soap with used oils for doing dishes.
So I wanted to share in case it interests you.

I like to made soap, and I realized I used more soap products in the kitchen then in the washroom. I like unscented products as well. I make liquid soap and bar soap to use in the kitchen.

I have made it with only canola oil. It was ok it did the job. But ideally you still want to combine different oils for best results.

I save all bacon fat drippings. And also render tallow when my hubby uses the smoker. I use a stainless steel fine mesh strainer container.

And a friend gives me her oil from the deep fryer, it's liquid oil. I put it in a tall container like a Coke 2L bottle and I leave to let the oil dirt settle, I dispose the very dirty botton oil. I found I made a big mess filtering it. If only filtering it works for you. Go for it!

Then I clean these oils by heating it and cooking some slices of ginger in it. Let it simmer in low heat. It's like you fry the ginger in the oil. (It's to reduce the smell from the food in the oils. It deodorizes it.)
I remove the ginger slices with a steel hot pot fat skimmer and let it cool down a bit then I use cornstarch mixed in water. You can google both techniques. There's lots of videos on YouTube about ginger and cornstarch to clean and freshen up used oil.

To make the soap, It's a little tricky to know what oils exactly I'm getting from my friend, it's liquid vegetable oil. Some blend of canola, soy, corn? My friend buys what's on sale and mixes the oils. And saves them for me

So I have to guess a little on my lye calculator. For dish soap I aim for a slight negative superfat. And I let the soap have a long cure and develop soda ash.

I add:
-sugar, I add 5-7% of oils weight.
-Citric acid, 5% of oils, it works as a chelator, helps with the bubbles and reduces soap scum.
Use soapmaking friend app to calculate the extra lye you will need.
Or use sodium citrate or another chelator that you don't need to adjust the lye.
-coconut oil 3-5% (even a little makes a big difference)
-Castor oil 2-3%
-Ethyl alcohol(from leftover hand sanitizer mine has 70% ethyl alcohol) 5% of oils(mix with the oils b4 adding lye, the alcohol helps the soap ladder and rinse off the dishes more easily. And gives you super shiny dishes. I Reduce the amount of water for the extra water in the alcohol.
I got a big jug for free. Post pandemic. I have not tried other alcohols. I heard here that rubbing alcohol makes a softer soap. Alcohol can be expensive.
-Aloe juice 1% of oils(just because I have it at home, helps with the bubbles too)

If you're hoping to make soap with used oils for personal use. With the recipe you had,
- I would try to add some harder oils
- keep a lower superfat like 1 or 2% if you add little to no coconut oil, you can get away with a zero, 1% or 2% superfat with a proper cure.
- reduce the water amount, I like 1:7 to 1 water to lye ratio.
- and add what you have on hand from the items I suggested above that I use in the dish soap, and do not use alcohol for personal use, it can lead to itchiness If someone has sensitive skin. Guess how I know it?

All the best in your soapmaking journey and luck with your experiments!

 

[Piero]

I've always wanted to try this, so am following closely. I have about 4 litres of used rapeseed oil from my deep fryer that are on its last legs I think.

I was considering trying this to clean it: https://www.seriouseats.com/clean-cooking-oil-with-gelatin-technique

Has anyone tried this before?

Also @Piero what did your soap smell like?

Let us know if you do it, sounds very interesting.

The soap produced does not have any odor at all It smells like soap. not sure how to describe it. It definitely does not smell like fried stuff. I have been told by friends that are chemical engineers and chemist that lye sort of takes away that smell, and it did

If you look at the predicted qualities of the soap recipe in the lower left. Under hardness your soap is predicted to have a hardness of 5, normal soap has a hardness of 29 to 54. Try several different oils and see how the numbers change, it can help you understand what is happening and how you can improve you soaps.

Ok

Then I clean these oils by heating it and cooking some slices of ginger in it. Let it simmer in low heat. It's like you fry the ginger in the oil. (It's to reduce the smell from the food in the oils. It deodorizes it.)
I remove the ginger slices with a steel hot pot fat skimmer and let it cool down a bit then I use cornstarch mixed in water. You can google both techniques. There's lots of videos on YouTube about ginger and cornstarch to clean and freshen up used oil.

Thanks for the suggestion, might try it to see what it does but honestly speaking the smell is not at all an issue since there is no scent that resembles fried stuff