soap

Want to share some knowledge of eco products. Or have you heard about any new eco projects that you want to share with the world?
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RuthG
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soap

Post: #246093 RuthG
Tue Oct 04, 2011 8:10 am

I have beenr eading some recipes for making one's own saop, but they all contain lye (caustic soda). Is there a recipe anywhere that uses an alternative, as I really dont want to be using something like that on my skin!

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contadina
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Re: soap

Post: #246094 contadina
Tue Oct 04, 2011 8:26 am

The lye and whatever oil you use both cancel each other out. Seriously, it's not an issue. I get repeat orders for my soap (made from olive oil, caustic soda and beeswax) from a lot of people with skin problems, such as eczema, precisely because it is so gentle on the skin. I've also not needed to use moisturizer since making my own soap.

The important part is to make sure you get your measurements correct by using an online lye calculator. Too much oil and the soap will be a bit too oily and to much lye and it will be a bit too harsh. You can make your own lye with wood ash but it works in exactly the same way as caustic soda. A lot of commercially produced soap use chemicals rather than lye and they are particularly harsh on the skin.

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The Riff-Raff Element
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Re: soap

Post: #246098 The Riff-Raff Element
Tue Oct 04, 2011 9:02 am

Contadina is quite right.

Soap is the result of a pair of consecutive chemical reactions: base catalysted hydrolysis of an ester (the fat) followed by formation of metal salts of the liberated fatty acids. The lye (usually sodium or potassium hydroxide - caustic soda and caustic potash) is consumed. Provided that the fat is maintained in small excess (no more than a couple of %), and that sufficient curing time is allowed, there should be no caustic material left.

Home made and artisanal soaps often benefit the skin because they contain this slight excess of the starting oil or fat and that the glycerine liberated during the hydrolysis stays in the soap.

Cheap commercial soaps are often produced using synthesised fatty acids from the petrochemical industry plus lye - any moisturisers have to be added and those go into only the more expensive soaps.

It goes without saying that when playing with hydroxides, eye protection, rubber gloves and a source of water to quickly wash away any splashes from the skin are highly advisable. Beyond that, it is fairly straightforward. My elder children (10 & 12) do it.

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Odsox
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Re: soap

Post: #246113 Odsox
Tue Oct 04, 2011 11:39 am

A quick question (sorry to hijack your thread Ruth) can you make an acceptable soap using chicken fat ?

I have an excess of the stuff and can't now use it in cooking :(
Tony

Disclaimer: I almost certainly haven't a clue what I'm talking about.

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Zech
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Re: soap

Post: #246137 Zech
Tue Oct 04, 2011 4:07 pm

I made a batch of soap using a mixture of lard and chicken fat, with just a little sunflower oil added to make up the quantity, and it came out really well. The sap values are the same for those two meat fats.
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Odsox
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Re: soap

Post: #246139 Odsox
Tue Oct 04, 2011 4:24 pm

Thanks Rachel, that maybe the answer then as I can't bring myself to chuck it away.
Tony

Disclaimer: I almost certainly haven't a clue what I'm talking about.


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