Rubbish soap.

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Rubbish soap.
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Hairyloon

Joined: 20 Nov 2008
Posts: 15425
Location: Today I are mostly being in Yorkshire.

Posted: Fri Apr 18, 14 8:12 pm Post subject: Rubbish soap.

I have been making soap. Not intentionally, it is an almost inevitable by-product of making biodiesel and considering what it is made of, it is probably not very good soap...
OTOH, surely to some extent soap is soap: a salt of a fatty acid. It is what it is mixed with that makes the difference... and mine is largely mixed with muck.

So the question is: can it be refined, and is it worth the effort?

jamanda
Downsizer Moderator

Joined: 22 Oct 2006
Posts: 35056
Location: Devon

Posted: Fri Apr 18, 14 8:19 pm Post subject:
I'd think not. I'd say the point of having homemade soap is what's not in it. How would you refine it anyway?

Hairyloon

Joined: 20 Nov 2008
Posts: 15425
Location: Today I are mostly being in Yorkshire.

Posted: Fri Apr 18, 14 8:38 pm Post subject:

Jamanda wrote:

I'd think not. I'd say the point of having homemade soap is what's not in it.

I wasn't really thinking of posh handmade soap: I was thinking supersaver basic soap. Presumably all the people reliant on food banks also need to wash?
There are a lot of people making biodiesel, so there must be gallons of the stuff just getting thrown away.

Quote:

How would you refine it anyway?

That is of course the big question. Quite a lot of the muck does seem to just wash out of it reasonably easily. Other than that, I haven't really tried anything yet...

jamanda
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Joined: 22 Oct 2006
Posts: 35056
Location: Devon

Posted: Fri Apr 18, 14 8:43 pm Post subject:
I think given what you need to make basic soap - lard or veg oil and Sodium hydroxide, refining your stuff would cost more than making it from scratch.

Hairyloon

Joined: 20 Nov 2008
Posts: 15425
Location: Today I are mostly being in Yorkshire.

Posted: Fri Apr 18, 14 11:41 pm Post subject:

Jamanda wrote:

I think given what you need to make basic soap - lard or veg oil and Sodium hydroxide, refining your stuff would cost more than making it from scratch.

You might be right, but it does depend upon what needs to be done to refine it, which depends upon what is in it that needs to be removed.
What could be in there?
We have not discovered alchemy, it can only be what we have put in or reaction products.
What goes in is chip oil, hydroxide and methanol, the reactions produce biodiesel, soap and glycerol. These do settle out into fairly distinct layers.
The oil might be fairly disgusting, but just before it came to me, somebody was cooking chips in it, so it cannot be very far from being fit for actually eating.
Most of the muck seems to come out in the wash.
Hydroxide is what you use to make soap anyway.
Glycerol is often found in soaps so I can't imagine it is a problem if there is some of that left in...
Which just leaves biodiesel and methanol.
Methanol is proper nasty, but most of it would be washed out and any remaining can be driven out by heat.

Neither washing nor heating is particularly costly or time consuming and can be done in sensible sized batches,

For comparison Tesco value soap costs £1.20/kg and is mostly made of palm oil...

Mistress Rose

Joined: 21 Jul 2011
Posts: 15598

Posted: Sat Apr 19, 14 5:24 am Post subject:

I think that commercially the glycerol is extracted and used for soap making. You will have the soap as a reaction between that and the sodium hydroxide I would expect.

You might try some experiments with the soap. First heat it above the boiling point of the methanol and keep it there for a bit to get rid of the methanol. Do this outside or with extraction as you don't want to inhale the fumes. Then let it set. Try with litmus paper or a pH meter to find how alkaline it is. You have to let soap mature until the hydroxide reacts properly. If there is still too much hydroxide, you could try adding more of the glycerol. Perhaps the soap makers can suggest some other suitable tests or methods.

Hairyloon

Joined: 20 Nov 2008
Posts: 15425
Location: Today I are mostly being in Yorkshire.

Posted: Sat Apr 19, 14 8:03 am Post subject:

Mistress Rose wrote:

You might try some experiments with the soap. First heat it above the boiling point of the methanol and keep it there for a bit to get rid of the methanol. Do this outside or with extraction as you don't want to inhale the fumes. Then let it set.

That was exactly what I had in mind... except I don't think it will set: I'm using potassium hydroxide, I understand that makes liquid soap.

Quote:

You have to let soap mature until the hydroxide reacts properly.

I only have a few gallons so far, so it is not high on my priority list: pretty good chance it'll have matured by the time I get around to anything.

Quote:

If there is still too much hydroxide, you could try adding more of the glycerol.

Aside from the cost, why not balance it with acid?
For a cheap source of acid, I did wonder about carbonic acid: simply bubble the exhaust from the central heating through it.

Quote:

Perhaps the soap makers can suggest some other suitable tests or methods.

That was what I was hoping.

Mistress Rose

Joined: 21 Jul 2011
Posts: 15598

Posted: Sat Apr 19, 14 5:30 pm Post subject:
Add salt to precipitate the soap. That was the way it was done when wood ash (containing potassium hydroxide) was used to make soap.

Hairyloon

Joined: 20 Nov 2008
Posts: 15425
Location: Today I are mostly being in Yorkshire.

Posted: Sat Apr 19, 14 7:30 pm Post subject:

Mistress Rose wrote:

Add salt to precipitate the soap. That was the way it was done when wood ash (containing potassium hydroxide) was used to make soap.

Good tip. Thank you.

sally_in_wales
Downsizer Moderator

Joined: 06 Mar 2005
Posts: 20809
Location: sunny wales

Posted: Sat Apr 19, 14 9:03 pm Post subject:

Historically, grey soap (soft soap made with poor quality fats, often salvage from cooking or bits from butchery with no better use) was used for textile scouring, so if what you have is effective soap just not nice enough for use in the bath or laundry, you could use it for fleece scouring or similar. If you want to sell it though, it will need certifying and compliance with EU regs, which will require you to be able to demonstrate the precise balance of each batch which may be tricky with pre used oil?

You may be able to clean it up a bit by dissolving it in water, filtering it, and reconcentrating it and adjusting the pH as you go?

Salting out has been mentioned, you do that by adding brine to the diluted soap and whisking furiously before letting it settle, in theory, youll get a layer of purer soap on top, and the spent brine below will also contain some of the impurities and a lot of the glycerine. Its only once uses such as explosive making are found for glycerine that methods develop to reclaim it, early soapmaking loses most of the glycerine during salting out

Hairyloon

Joined: 20 Nov 2008
Posts: 15425
Location: Today I are mostly being in Yorkshire.

Posted: Sat Apr 19, 14 9:11 pm Post subject:

sally_in_wales wrote:

it will need certifying and compliance with EU regs, which will require you to be able to demonstrate the precise balance of each batch which may be tricky with pre used oil?

Balance of what?

sally_in_wales
Downsizer Moderator

Joined: 06 Mar 2005
Posts: 20809
Location: sunny wales

Posted: Sat Apr 19, 14 9:15 pm Post subject:

Essentially, the exact recipe in a way that can be reduced to a chemical formula by the chemist doing the paperwork, so 'unknown percentage of potato bits and onion bhaji' might be problematic. With my soaps, they need to be able to access the analysis sheets for each ingredient if they feel like it, hence most soapmakers sticking to regular suppliers who can provide traceability of each ingredient.

gythagirl

Joined: 18 Feb 2010
Posts: 1467
Location: Somerset

Posted: Sat Apr 19, 14 9:45 pm Post subject:
...and there was me thinking you meant Eastenders...

Hairyloon

Joined: 20 Nov 2008
Posts: 15425
Location: Today I are mostly being in Yorkshire.

Posted: Sat Apr 19, 14 10:54 pm Post subject:

sally_in_wales wrote:

Essentially, the exact recipe in a way that can be reduced to a chemical formula by the chemist doing the paperwork...

Unless I can come at it the other way and determine the chemical formula by titration or whatever, then that has scuppered that idea.

sally_in_wales
Downsizer Moderator

Joined: 06 Mar 2005
Posts: 20809
Location: sunny wales

Posted: Sun Apr 20, 14 5:25 pm Post subject:

Hairyloon wrote:

sally_in_wales wrote:

Essentially, the exact recipe in a way that can be reduced to a chemical formula by the chemist doing the paperwork...

Unless I can come at it the other way and determine the chemical formula by titration or whatever, then that has scuppered that idea.

that won't do it for certification purposes, you'd also need to be able to demonstrate the supply chain and suitability for 'cosmetic' use (according to the EU definition) for each ingredient if challenged, and I'm assuming that the variety of things cooked in used oil is automatically going to prove that impossible. Doesn't stop you using the soap yourself for laundry or similar if you can demonstrate to your own satisfaction that its clean and fit for purpose

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