Wood ash lye - asking for a friend

[szaza]

Hey Everyone!

I was wondering if some of you might have some extra tips for a starting wood ash lye soaper. I'm not talking about myself, but a friend of mine who lives in Uganda. They've been on lockdown for a long time already, but the amount of confirmed corona infections is rising, so the lockdown won't be lifted anytime soon. Meanwhile prices of basic needs like food and soap are rising. I suggested she might be able to make her own soap, which would be a cheaper alternative to store bought soap and possibly a source of income.
Because of the lockdown she doesn't have access to commercial lye, which leaves wood ashes as the most accessible sourse of lye. It's the rainy season, so she can easily collect rainwater and she can also get lard.
However, I don't want to set her up for a bunch of failed batches. I'll probably try it myself to be better able to guide her through the process (something I wanted to try at some point anyway), but any help/input from an experienced wood ash lye soaper would be greatly appreciated. Or if an experienced wood ash lye soaper out there feels like taking the time to teach her, that would even be better!
I've been reading up on wood ash lye and there are a few things that stuck out to me and I wanted to run by some people with more knowledge & experience on the subject.

1. I've read a lot of websites/seen a lot of youtube clips with false information (things like 'lye from ashes is sodium hydroxide' or 'potassium carbonate reacts with water and turns into potassium hydroxide' or 'you can make bar soap with wood ash lye by adding a bit of salt'). Can anyone point me in the direction of a good website about wood ash lye soapmaking? (besides @DeeAnna's soapy stuff, which is amazing by the way)

2. It seems like the most difficult part of making wood ash lye soap is figuring out the ratios of lyeil, because you never really know the concetration of the lye. Would it be an option to make a fully cooked, lye heavy soap and salt it out at the end of the cooking process to remove the excess lye? In theory that should make a pretty standardized bar right? Or am I overlooking something? On the soapy stuff page, salting out is only mentioned when people started to use slaked lime to make potassium hydroxide and then it was used to make a harder bar, not to take out excess lye. Is there any reason salting out wouldn't work to remove excess potassium carbonate?

3. Does cooked wood ash lye soap also show different stages of trace like regular CP soap? And how about mashed potato/vaseline stages like in HP? I somehow expected it to be completely different and it seems different in some video's that are cooking on very high temperatures, but then I saw a video of a guy making wood ash lye soap where he stirred the soap on gentle heat until (thick) trace occurred and then molded his soap, which kind of took me by surprise. Not everything he says in the video is correct (like pretty much every video I found so far), so I'm a bit cautious to just follow his example.

4. Is there a recommended ratio of water:ashes? For example, will the leaching be significantly faster if you use more water or will it just mean you need to boil it down for longer afterwards and therefore take more time instead of less?

5. Is there an added benefit to cooking the ashes in water ('making a tea') vs just letting them sit in cold water for a while? Will cooking the ashes speed up the leaching enought to make it worth the trouble of cooking?

 

[Ale]

Hello, I'm not an expert soap maker at all, but I'm very interested in the topic. I studied it and as soon as possible I would do some experiments. In my opinion, you idea about salting out soap to remove the excess alkalinity can't work very well because salt is made of sodium (NaCl) while wood ash lye is mostly potassium (K2CO3).
By adding salt, you would convert part of the potassium soap into sodium soap (and that is why it becomes harder) but you will loose all the potassium soap if you separate the saltes out soap from the solution. There's a thread called, I think, "Making soap the really old way" on the topic in which DeAnna explains very well why pioneers didn't used this method while industrial soap makers could do it.

Furthermore, I posted a thread some time ago called "wood ash lye challenge" in which I asked about a method that I had thought about for obtaining a lye of known concentration. It wasn't considered very good so maybe you shouldn't follow it, but maybe you would be intereated in some of my ideas. I repeat that I've not tried them yet and that others (DeAnna included were skeptical, so maybe you shouldn't rely too much on it)

 

[szaza]

Thanks for the reply @Ale I was just reading your thread I really liked your ideas (especially weighing a reference volume of wood ash lye water to determine density instead of floating an egg or potato), but if someone like DeeAnna is sceptical that's a bad sign
I knew there must be a drawback to salting out wood ash lye soap. It was too easy not to see it all around the internet. Too bad!

 

[Ale]

This is the post about the different methods of making soap with ash I told you:
https://www.soapmakingforum.com/threads/making-soap-the-really-old-fashioned-way.76996/post-796768

 

[szaza]

This is the post about the different methods of making soap with ash I told you:
https://www.soapmakingforum.com/threads/making-soap-the-really-old-fashioned-way.76996/post-796768

Thanks! Found it and read through it yesterday

Hmm.. I'm starting to wonder if for the purpose of making soap with easily accessible resources (in other words, no NaOH) whether sodium carbonate would be an option. If soap can be made with potassium carbonate, it seems logical sodium carbonate should work as well? (I should ask her if that's available to her). That way the process would probably be faster and more reliable.

 

[Ale]

It should work and produce harder bars than potassium carbonate (I think comparable to those made with NaOH). But I fear that you must use it more like wood ash lye than like NaOh or KOH.
I mean, I don't think it's suitable for a CP, and maybe neither for normal HP. But you should wait for further answers from more expert people

 

[szaza]

Thanks @Ale ! I really appreciate all your help☺
I always thought that making soap with sodium carbonate was impossible, but if it's possible with potassium carbonate, the process with sodium carbonate should be similar. Maybe if the oils are heated enough the fatty acids might break from the glycerol at a lower pH? I'm honestly really not sure about this and I'm wondering if it's actually possible.
That said, my wonderful BF helped out a bit by searching the web (he has access to full chemical articles and understands them a lot better than I do). He found that calcium is the most abundant metal in wood (ashes), followed by potassium and even less sodium. The ratio of those three differs per tree. If wood is burned hot enough (I think he mentioned 1400°C), the calcium will turn into calcium oxide - which becomes calcium hydroxide in water. Potassium will do the same, but later/at a higher temp (need to recheck which of the two or if it was both). In other words, there might be some potassium hydroxide in the mix as well as calcium hydroxide when using well burnt white ashes (he suggested using a kiln to reheat the ashes could help to make sure everything has been hot enough).
What I'm getting at here is that the oxides in wood ash lye might make for a higher pH than just straight up potassium carbonate, which in combination with added heat from cooking the soap might just be enough to saponify, while pure sodium carbonate might not do the same.

(Edited because my clumsy fingers accidentally posted while in the middle of writing )

 

[Ladka]

I found a video at

(23 minutes) where a guy actually makes soap from wood ash lie and lard. I think it is worth watching.
And I love his description of the aspect of the soap obtained and of the speed at which lard traces:
" ... don't expect soap you can sell on amazon. its really just something that should be used if you absolutely have to... first you need to make lye from wood ash (lye water), then you spend the rest of your life stirring it... "

 

[Ale]

@szaza, I'm not the most reliable person in chemistry but I think you miss a point. The problem is that it's very difficult to obtain those high temperature in a common stove. That's the reason why, in my opinion, wood ash lye contains Potassium and sodium carbonates and not hydroxide (Calcium carbonate is nearly insoluble so it does not remain in the lye).
Anyway, pure sodium carbonate should be better than common wood ash lye (because is sodium and because it's pure). What I meant was that your friend should learned how to use it, and the method would be more similar to that of wood ash than that of NaOH.
I think she should forget CP, while MAYBE (that's what I'd like to try) HP could work

 

[szaza]

Thanks for the info @Ale! I'm not at all aware of burning temps of wood fires, so it's good to know most won't be as hot as required to make potassium hydroxide

I found a video at

(23 minutes) where a guy actually makes soap from wood ash lie and lard. I think it is worth watching.
And I love his description of the aspect of the soap obtained and of the speed at which lard traces:
" ... don't expect soap you can sell on amazon. its really just something that should be used if you absolutely have to... first you need to make lye from wood ash (lye water), then you spend the rest of your life stirring it... "

Yes, it's a good video I was surprised at how similar trace looked to cp soap.

 

[Ladka]

In my country, soap used to be made through pure experience and without much scientific knowledge, from wood ash, preferably from hardwood, and animal fat. They used ashes from house fireplace. They made it on the alkaline side because fats were by far more precious than ashes so they made sure all of the fat was used.
What was obtained was soft soap, of varying smells and appearance, depending how much cleaning the fats was considered. Considering that even remnants of food fats were used after storage until there was enough of it this may not be a very pleasantly smelling soap but cleansing it was.
Also, a few years ago a project was carried out on the traditional soapmaking. Animal fats were used, ashes were just put in water together with fats and heated. I was told the soap was ugly to the eye and offending to the nose - but cleansing it was

 

[szaza]

I finally sifted the ashes and made a slurry that I cooked on the stove. One thing that stood out is that barbeque ashes (charcoal fire) were whiter than wood stove ashes (wood fire).
After cooking, I thought it'd have a look at pH with some litmus paper. It looked like the pH is well above 12, which is an indication there could be at least some hydroxides in there.. I know litmus paper isn't super reliable in the upper ranges, so I let the slurry cool down and meanwhile mixed a (+-saturated) sodium carbonate solution to compare it to. The ash soup seems to be higher in pH than the sodium carbonate (I redid several times and got the same outcome every time). Potassium carbonate would've been a better comparison, but I don't have that at home.

Left strip is sodium carbonate, right is ash soup in both pictures (the difference was always clearer right after dipping the strips in liquid, but taking a picture meant a bit of delay)

I filtered the water off the top of the ashes, put the leftover slurry in a sieve with a cloth and I'm filtering rain water through it. I intend to continue checking pH, to know if I'm still leaching out the stuff that I want (I decided I'll stop when I test below pH12). I'm mainly curious if there's a link between pH and color. I saw a video where the guy said the color was related to the amount of lye in the water, which I'm a bit sceptical about because I'd expect lye to be colorless, but it would be a great visual cue if true☺
I'm also wondering if I should've just boiled the ashes with a lot more water, because filtering water through it to leach more out takes forever.. although I have the idea that the litmus paper looks darker blue (more alkaline) on the filtered water than on the water I used for boiling. Unfortunately I can't check that because I already mixed them.

Eta: I know the exact amount of whatever alkali substance is in there is not determined by pH, I just thought the pH would drop when there's no more alkali left to leach out. However, I just realized I might not want to go that far, because I'd be adding a whole bunch of extra water that I'd have to boil off again. I should probably check the density rather than pH..

 

[bookreader451]

I watched the video and it looks like he measured the lard using water displacement, which is more accurate than just filling a cup with lard. He must know what ratio works for him but he should specify on the lard.

 

[szaza]

Thanks @bookreader451 I hadn't noticed that.. I'll watch the video again

 

[szaza]

ETA: this turned out to be a very long post. It's mainly a description of my experience. I posted a question in the post below.

I finaly made the wood ash lye soap.
I started checking the density of the filtered ash water after posting on wednesday and stopped filtering when the density got too close to that of water (1.001g/mg) even after filtering several times. The pH was still as high and the color was still there at that point. Next time I'll probably just boil my ashes with more water and leave out the extra filtering step. (By that time I had used about 2.5L of water (half of the amount of ashes I started with, or +-1.5 times the amount of sieved ashes, which I'll probably use as a guideline for the future)

All the filtered ash water together was 823g and had a density of 1.02-1.03g/ml.
My freshly laid eggs had a density of about 1.07-1.09g/ml (the actual measured range was 1.04-1.1 because I couldn't measure water displacement accurately enough - can't put a whole egg in a tiny cylinder so I had to use my kitchen measuring cup - but after measuring each egg 3 times, I'm fairly certain the real range was 1.07-1.09). I also found an article that found similar densities for (old) potatoes (here), so that's the density I went for as a guideline - boiling the water down to between 20-30% of the original volume. Once I eyeballed it would be boiled down enough I had 223g ash water left, with a density in the 1.07-1.09g/ml range. It floated an egg, but it wouldn't dissolve a poultry feather (not even after several hours), which I had also read could be used as a test and seemed less wasteful than sacrificing a perfectly good egg.

I found a lot of different starting points for the ratio of fat:ash water online, all the way from 1:0.375 until 1:4, so I decided to calculate an estimation.
If the dissolved substances in my ash water would all be potassium hydroxide (I know they're not, this is just an oversimplification to make this calculation doable), how much would I have? I used potassium hydroxide, becasue I found a more reliable online density to solution strength calculator (here) and it's part of the most common soap calculators. Potassium carbonate would be fairly similar, but have a slightly higher % solution by weight at the same density (see here)

I started with 823g of filtered ash soup with a density of between 1.02-1.03g/ml and ended up with 223g of concentrated ash soup with a density of between 1.07-1.09g/ml. I calculated that if all the dissolved substances would be potassium hydroxide (KOH), I had 20-30g before and 18-23g after concentrating, so I took 20g KOH as a starting point for calculating.
20g of KOH could saponify the following amounts of lard* for different % of lye purity
90% purity - 90g
80% purity - 80g
70% purity - 70g - you get the gist, I was super excited about getting these easy to work with numbers

If you want to see a slideshow of how the soap boiling process went, I put a short video online


Here's the written transcript of how the cooking process went for anyone interested:
I started out with 45g fat (half of what maximum KOH purity could saponify) and added a bit of egg (14g or +-¼ egg) to not let it go to waste. I added +- half the amount of concentrated ash water (110g) and a teaspoon of salt. I cooked on very low heat until the soap started to boil/volcano. I stirred it down, reduced the heat and after that it seemed done quite quickly. I zap tested the batter and it was negative, so I added 10g of extra ash water and cooked again. This (cooking, zap testing, adding 10g extra ash water) was repeated several times until the zap test was positive (a slight tingling sensation). At that point I had added +-40g extra ash water (so 150g total). This was +-2/3 of the total ash water and I had +-1/3 left, so I measured out half of the fat and egg that I had added before and mixed them together (23g fat & 7g egg). The soap mixture was a bit dry, so I first added some more ash water, than the extra fat and lastly the rest of the ash water.

In the end I used 68g fat, 21g egg (2.1g extra fat), 214-223g ash water and 1 tsp of salt. (I had 223g ash water before starting, but only measured adding 214g, not sure where the other 9g went)

Next time I will calculate my starting amount of ash water and fat based on a 70% KOH purity, but still keep extra on hand in case the calculations turn out to be off, so I can add extra soup or fat if needed.

The bar turned out a lot harder than I expected, although it’s by no means a regular bar of soap.

* for the people who know me.. yes I used lard, it's totally against my principles, but it's what my friend will use. From what I read it behaves very different from other soaping oils, so I didn't dare use a vegetarian substitute in fear of it behaving differently and not being a good representation of the process that she will go through.

I have one more really important question. The soap lathered quite nicely immediately after cooking, but I tried it again a few days later and it's incredibly slimy and I have no idea why.. I never read about wood ash lye soap being slimy and I have no idea what caused the slime since I didn't use any high oleic oils, I used a bunch of salt (which in regular soaps is supposed to reduce slime), and I thought potassium (hydroxide) could be used to cut down on slime in high oleic sodium soaps. @Ale I know you've tried wood ash lye soap several times.. has slime been an issue for you at some point?

 

[dibbles]

I finaly made the wood ash lye soap.

I am so impressed!!

 

[Ladka]

I finally made the wood ash lye soap...

Excellent, Szaza! I admire your approach, your perseverance and your readiness to help a friend with your expertise.
And I'll make use of your results and try you make a wood ash lye soap - it's been waiting on my wish list!

 

[Ale]

Hi @szaza , well done!!!
Indeed, I'm far more expert in theory than in practice of wood ash lye soap. I've studied the topic a lot and I made some experiments. Then it came the lockdown and I remained in my house in the city, where I have no way of providing ashes. And when lockdown finished, univeraity exams started... I will do it again as soon as I could go to my cottahe in the mountains (I hope not later than a week or two).
Regarding the slime, I honestly do not know, but i suspect it could be caused by the excess lye. Wood ash lye is very slimy (the first time, when I was a complete newbie, I didn't wear gloves and I remember the strange slimy sensation when lye touched my skin). Maybe your soap is "sweating" the excess lye? I don't now if it's possible but of it were, I imagine it should have this effect

Excuse my English and the orthography,...

 

[szaza]

@Ale thanks for the reply and good luck with your exams!! I hope they're going well
I don't think the excess lye will be the cause of the slimyness. The last zap test was negative, so it seems unlikely there was any excess lye. The slimy/slippery feeling of lye on skin is caused by the lye saponifying some of the sebum on the skin, but These are slimy threads coming from the bar itself

 

[Ladka]

@szaza, what happened to your wood ash lye soap in these two years? Did you cut it into bars or did you pour it into smallish containers and use it as creamy soap?
P.S. My ashes are still waiting in the cellar