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Hey, Demi!

I just found some old episodes of Rough Science on Youtube, including one where they make soap from scratch:
http://www.youtube.com/watch?v=5f2lVPBZ ... ature=plcp

It's not very informative, and nothing resembling guidelines on strength or quantities, but quite entertaining.

thats grate thanks Rachel!

need to wait just now till the end of the summer when we get the pig to butcher so i can save up the fat.
we've not been eating too much meat recently, been eating lots of soya and beans instead, so i dont really have decent amounts of fat to take off the meat.
but we get a whole pig and divide it between the family so ill take the fat from it for soap making.
does it not smell funny when its made from animal fat?

Demi,

The old school way of measuring the srength of lye was a "lye stick". This will float upright at a given SG and hence concentration. Clearly a modern and more simple fashion is a cheap digital pH meter. If you have a Ph Meter, you easily make a lye stick as a backup.

Red

a PH meter. what PH is it supposed to be? sounds like a more accurate way of measuring it.
iv seen it done with a raw egg. when the egg floats its the right strength.

demi wrote:does it not smell funny when its made from animal fat?

Surprisingly, no. Once the fat's reacted with the lye it just smells like soap, not meaty at all.

demi wrote:a PH meter. what PH is it supposed to be? sounds like a more accurate way of measuring it.
iv seen it done with a raw egg. when the egg floats its the right strength.

Just calibrate the required strength in your favourite recipe. If you dissolve the caustic soda in water as normal, then measure the alkalinity, you make your wood ashed based lye and then boil the mixture down until the required alkalinity is reached

Red

is it possible to make a ph neutral soap from wood ash lye and animal fat ?
iv got eczema on my hands which is constantly aggravated by soap from washing dishes ect. im always using hydrocortozone near enough every day which i know your not supposed to coz it thins you skin or something. but my eczema will clear up for a week after using the cream then just flair up again because iv constantly got my hands in soapy water all day.
it can be crippling sometimes, i cant do anything as my hands are cracking and bleeding. my skin gets irritated by anything wet, but soap is particularly bad.

The best I have made for people with skin conditions is soap made from pure olive oil. Its very mild, small lather but good cleaning.

Red

olive oil is too pricey here to make soap from. everybody uses sunflower/veg oil instead.
funny that, concidering we border with greece!

demi wrote:is it possible to make a ph neutral soap from wood ash lye and animal fat ?

I'm quite sure it's possible, but less sure about exactly how to achieve it. With bought lye and a nice, carefully controlled ratio between lye and fat, the lye should all react with the fat (recipes always include a bit of extra fat to make sure this happens) so it shouldn't be alkaline by the time it's finished curing. I guess that means it will end up with pH 7 (neutral) which is the same as pure water but isn't quite the same as skin pH, which I believe is a bit acid. You probably knew all that already.

As for wood ash lye, I'm sure Red's right that the goal is to match the pH of the wood ash lye solution to the pH of a recipe lye solution. I've looked these up and it's usually around one measure of caustic soda to two and a half measures of water, by weight. It's a bit variable from one recipe to another, because the quantity of lye is calculated based on precisely which fats/oils are used, then the quantity of water is calculated separately based on... I'm not quite sure, but I think it's just volume of fats/oils. I don't have a pH meter, but I'm trying to do this by titration. I'll let you know if and when I succeed

I suspect that home made, cold process soap will be better for your hands than commercial stuff because of the glycerine content. Glycerine is a by-product of soap making which is removed in commercial processes (so they can sell is separately) but left in with home made soap. I believe it's good for skin, but I don't really know what I'm talking about, I'm only repeating what I've read here. Maybe someone who actually knows about these things will contribute!

Zech wrote: As for wood ash lye, I'm sure Red's right that the goal is to match the pH of the wood ash lye solution to the pH of a recipe lye solution. I've looked these up and it's usually around one measure of caustic soda to two and a half measures of water, by weight. It's a bit variable from one recipe to another, because the quantity of lye is calculated based on precisely which fats/oils are used, then the quantity of water is calculated separately based on... I'm not quite sure, but I think it's just volume of fats/oils. I don't have a pH meter, but I'm trying to do this by titration. I'll let you know if and when I succeed

The situation is made a little more complicated because the alkali in wood ash lye is (more than 90%) potassium hydroxide with only a little sodium hydroxide. Measuring the pH precisely will allow you to find the molar concentration of the hydroxide ion easily enough, but the resulting soap will mostly be a potassium soap, more of a soft soap, than one made with caustic soda. I'm not sure that the amount of water is set by anything more than a desire to make sure the reaction mixture is sloppy enough (that's a technical chemistry term. Honest.) Finished soap that has been left to dry ends up with a bit less than 10% water.

Zech wrote:I suspect that home made, cold process soap will be better for your hands than commercial stuff because of the glycerine content. Glycerine is a by-product of soap making which is removed in commercial processes (so they can sell is separately) but left in with home made soap. I believe it's good for skin, but I don't really know what I'm talking about, I'm only repeating what I've read here. Maybe someone who actually knows about these things will contribute!

Super fatted soaps made via cold process and so containing the glycerol are better for the skin, mostly because they replace the oils in the skin that are removed by the detergent action of the soap.

That said, if one is going to use would ash lye without a clear idea of the the amount of alkali being played with, then hot process might be a better option at least from a safety standpoint, but the glycerol is lost with the liquor. I don't know if glycerol could be added back in to the hot soap while it is still soft before going into molds. I'm not a fan of the use of boiling caustic in a domestic setting

If you hot process your soap in the microwave there's no liquor, so nothing lost. It's just about the only thing I use mine for

Definetly on our to do list. We have had two good seasons of olive oil and are starting to build up some surplus. Thank yo all for the information and links.

I'm going to attempt the wood-ash soap in the summer at the Medieval events we go to. I reckon that if i manage to make some voer one weekend and stick it in a jar, then it should be ready to use the next weekend. As far as I can work out from what I've read, it seems that the potassium hydroxide soap cures almost straight away and makes a soft, jelly like soap. It's good for washing up and washing clothes and stuff (and quite period-appropriate for what we do).

I'll have to sneak in some litmus paper to check the acidity though. I don't mind licking a solid bar of soap, but i'm not too keen on licking soap jelly.

Green Aura wrote:If you hot process your soap in the microwave there's no liquor, so nothing lost. It's just about the only thing I use mine for

I'm intrigued, though I assume here you'd be using carefully weighed amounts as per the cold process. Can you describe the process? I've never considered using a microwave for soap making for fear of decorating the inside with caustic

I was thinking that in a situation where one was a bit hazy about the weight of alkali to hand, as in home-made wood ash lye, a boiled hot process soap would probably give the safest and most reliable outcome.