Superfatting repurposed soap?

[hajonnes]

Hi,
I have some old olive oil hard soap that is rather harsh on the skin.
Now I would like to try to repurpose it as a base for making a shaving soap.
I was thinking of perhaps superfatting it and add some glycerol to the mix.
But how much should I add?
Before I have melted the soap with some water in the microwave and added some olive oil during mixing.
But I have no way of knowing how much fat and glycerol the mix can take. Can I somehow see from the reaction or from ph that I should stop adding fat?
Should I add glycerol at all? If yes how much should I add?

On a side note, What is your recommendation on fat to add?
I have olive oil, coconut oil.


I like the idea of the unused old soap transformed into something that I will use, instead of it just collecting dust in the cuboard.

 

[DeeAnna]

Yes you can "rebatch" soap -- melt it with added liquid and other ingredients such as extra fat. Either olive oil or coconut oil would be fine as an added fat. Use whichever one feels best on your skin.

How much extra fat you add is up to you, but I personally would add no more than 5% fat by weight, based on the weight of soap. Adding a lot of extra fat will not necessarily make a soap milder, but it definitely will reduce the lather.

The only reason why I would add a larger amount of fat is if I knew there is too much alkali in the soap due to an error. Then I would calculate the extra fat needed to chemically react with the extra alkali.

Adding fat won't change the pH of soap, unless the soap contains excess alkali. And even in that situation, measuring pH alone is not enough to learn when all of the excess lye has been consumed.

Handmade soap made from fat already has about 8% glycerin (glycerol) in it. Adding more glycerin will decrease lather, increase the softness, and won't necessarily reduce the harshness. Why do you want to add more?

An olive oil soap is not going to be a very nice shaving soap -- the lather is not slick and dense enough to protect the skin. Also some people's skin is sensitive to olive oil soap, even if it is properly made. If your skin is sensitive to olive oil soap just when you use it for bathing, I do not think it would be wise to also use this soap for shaving due to the slight irritation created by shaving.

 

[Hermit]

Could it be shredded and added to a new soap batch to make confetti soap? Or maybe repurposed as a laundry soap?

 

[hajonnes]

Thanks for the rsponses. I ended up finding a palm oil soap.
I mixed olive oil, water, the shredded olivoil soap and the palm oil soap and remoulded it.
It ended up as a confetti soap. that I use for shaveing.

What I take away from this experience is that the palm oil soap (which is 90% of the soap) was good as a shaving soap.
I do not know if the olive oil made it better, but the end result is comparable to shaving soaps that I have used before.