Hello everyone, as I said in the introduction, I’m new to soap making practise but I’m very interested in the topic. As many beginners, I originally wanted to try wood ash lye soap-making. After some failed experiments I decided to use NaOH, and things begin to go really better. But I’ve continued studying the issue of wood ash lye and now I’ve a very big questions to ask you.
One of the biggest problems related to wood ash lye is the difficulty of determining its composition and concentration. So, my question is: do you think is it possible to create a method for standardizing the concentration of your lye?
And moreover: has anyone thought of determining a sort of “wood ash lye saponification value”, to know (more or less precisely) how much lye of a known concentration we need for a specific fat?
I see that it could seam a bit ambitious as a project, but I don’t think it’s so impossible as it seems. Personally, I would face the problem following three steps:
Sorry for the long text, and forgive me if my English is not always perfect.
One of the biggest problems related to wood ash lye is the difficulty of determining its composition and concentration. So, my question is: do you think is it possible to create a method for standardizing the concentration of your lye?
And moreover: has anyone thought of determining a sort of “wood ash lye saponification value”, to know (more or less precisely) how much lye of a known concentration we need for a specific fat?
I see that it could seam a bit ambitious as a project, but I don’t think it’s so impossible as it seems. Personally, I would face the problem following three steps:
- Minimize the differences in the chemical composition between a lye and the other à you must use always the same species of wood and try to burn it always in the same conditions (e.g.: beech wood burnt in a modern stove). Then you can choose to add slacked lime (as described in this Forum) or not, what is really important is to follow every time the same process.
- Standardize the concentration and find an easy (but precise) way to measure it à That’s the most interesting part of the issue. I see three different ways that you can choose:
- Choosing a “reference concentration” which represents the optimal force of your lye and attempt to reach it every time. For example, you can use the famous floating egg method to know when your lye is satisfactory, then you measure the concentration with a more precise method. For the following experiments you won’t need the egg anymore, you will simply concentrate your initial lye until you reach the “reference concentration” that you measured the first time. Maybe, the most precise measurement method is titration. But it’s quite complicated. A valid alternative is the hydrometer. If someone is interested but doesn’t want to buy it, at this link (Flag of the planet Earth - Official Website) there’s a project to a wooden hand-made hydrometer. It’s an Italian website but if someone wants, I could provide a translation (I’m not so sure about how reliable it could be, but at least, it’s surely better the floating an egg or a potato). Furthermore, if you have a precision balance you could simply weigh a known volume of solution (this is maybe the simplest method but nobody mentions it; is there any reason?)
- Boil your lye until you see some precipitate (small crystals similar to salt) on the bottom of the pot. When it happens, your solution has reached the saturation, which means that it contains the maximum amount of dissolved solutes. This amount is always the same (at the same temperature), because it depends on the chemical nature of the solutes (and not on how long you let the lye boil). So, when you see the precipitate, your lye has always the same concentration, and you can simply collect the liquid part (after it has become cold, otherwise it will form some more precipitate) and discard the salt. The final lye produced in this method, will be stronger that the one commonly used, but this is not a problem as you can simply dilute it whit a known amount of water before using it.
- Someone boils the lye until it’s completely dried, then he recovers the precipitate and dissolves it in a certain amount of water, to reform a lye of known concentration. This way is certainly correct, but I think that it only makes things longer. You could use method B instead and reach the same results.
- Determine how much lye we need for our fat: That could be a very long process if you want to find the “lye saponification value” of every fat! However, you can at least try to do it for the most commonly used ingredients such as coconut, palm, and olive oil and some animal fats as tallow and lard. You’ll have to weigh a small amount of a single fat, make a saponification with excess of alkali, and then make a titration to determine how much lye has reacted.
Sorry for the long text, and forgive me if my English is not always perfect.