soap making book
essential oil properties
cold process soap
preparing to mix
gel & unmoulding
hot process soap
hot or cold process?
double boiler hot soap
oven hot soap
DWCP [Discounted Water
Cold Process] soap
how to discount
DWCP en Français:
mises en garde
DWCP: versione italiana
how to make milled soap
remilled soap methods
body care recipes
natural house care
natural soap bases
aussie soapers e-forum
soap mailing list
or how to survive a close encounter with LYE!!!
You might have heard that lye is a very dangerous chemical, and that soap is only good for your skin if it doesn't contain any lye... or, even better, if it has never been in contact with this dangerous substance.
First of all, let's clarify what lye is. Here's the entry from the Merriam-Webster online dictionary:
- Lye - noun
- 1 : a strong alkaline liquor rich in potassium carbonate leached from wood ashes and used especially in making soap and washing; broadly : a strong alkaline solution (as of sodium hydroxide or potassium hydroxide)
2 : a solid caustic (as sodium hydroxide)
In soapmaking, lye is a generic term used to describe both the solid caustic substances, and the alkaline solutions made by dissolving sodium hydroxide (chemical formula: NaOH) or potassium hydroxide (chemical formula: KOH) in water. The terms "(strong) alkaline solution", "lye" or "lye water", "caustic soda", "alkali", "potash", "NaOH" and "KOH", all refer to this basic soapmaking ingredient.
While it is absolutely true that lye (as defined above) is a very dangerous substance, there is no way to make soap without using it. Making soap with no lye is very much like trying to drive a car with no petrol (or gasoline, as some call it) - and just like with petrol (gasoline), we accept the danger to obtain some benefit. Mind you... in many ways, lye is a lot less dangerous than petrol, and it's definitely nowhere near as polluting as petrochemicals are! But still, a lot of people drive cars without worrying, and choose to worry about lye (one of the many mysteries of the universe.... :-)
Back to the unavoidable relationship between soap and lye, please don't take my word for it, and do your own research about what soap really is!
Some useful (and unbiassed) sources to understand what soap is about include:
- any good dictionary (you might be surprised to discover how useful a plain old dictionary can be :-)
- a description of the chemistry of soapmaking written by the Assistant Professor of Chemistry at the Department of Environmental & Health Sciences, Johnson State College (VT - USA)
- a brief note about soapmaking from the University of Oxford, UK
So.... if soap always involves using some sort of "lye", what are these "lye-less" soaps some people go on and on about?? Well, I have reason to believe that "lye-less soaps" are either made by remilling an industrial soap base (in which case, the person who's "remilling" the soap doesn't come in contact with the raw materials, and therefore might believe they are working with a "lye-less" base), or they are a purely synthetic detergent.
If you want to make soap, you have the choice to either come to terms with lye - or you can choose the easy road, and purchase a natural soap base for hand milling, also known as rebatching or, less appropriately, as remilling.
Working with lye
If you choose to make your soap from scratch, you'll have to learn how to use and respect the alkali (sodium or potassium hydroxide) and the alkaline solution you'll be adding to the fats and oils. Here are some general recommendations about dangerous chemicals, and our suggested procedure:
- Always store NaOH and KOH in air tight, sturdy plastic containers, clearly and VISIBLY labelled "DANGER! - Potassium Hydroxide", or "DANGER! - Sodium Hydroxide" (adding skull and crossbones won't hurt :-)
- Keep your NaOH and KOH containers in a safe place, where they cannot be reached by kids, pets or people who can't read (or won't take any notice of the label)
- If you are buying dry lye (NaOH flakes or pellets, KOH flakes) in large amounts, chances are they will be delivered in thick plastic bags. Once you open the bag, it is highly recommended to transfer all its contents to sturdy, air tight plastic storage containers, which you can open and close without risking to spill the contents (which happens very easily with the bags...). Hardware stores sell large plastic buckets with air tight lids that can be used for this purpose. Also, you can talk a local deli/restaurant/hamburger or fish & chips store, and ask them if they happen to throw away plastic drums that could be washed and reused. Don't forget to label your storage containers, as explained above!
- Whenever you are working with the dry alkali, you'll need to wear safety equipment. In particular, you'll always wear the following:
- safety goggles
- rubber gloves
- long sleeved shirt
- sock, shoes and long pants
- When I repack my alkali, and every time I make liquid soap (which requires using KOH), I also wear a "bandit mask" to protect my mouth and nose, made by folding in half diagonally an old teatowel, or some other thick cotton rag.
- It is however prudent to always wear a mask every time you work with lye, and while you are preparing the caustic solution.
- To make soap from scratch, you will need to "prepare the caustic solution", which means, dissolve the chosen alkali (NaOH for bar soap, KOH for liquid soap) in water or some other liquid. Remember to always add the alkali to the water, and not viceversa.
- Choose the "right" containers for both the dry alkali, and the liquid you will dissolve it in. Both containers will have a nicely fitting lid that you can remove easily, without spilling the contents. I find plastic is best: the plastic container for the dry alkali can be a clean "take-away type" tub, while the container for the liquid must be made of sturdy plastic, and must have a capacity of at least twice the amount of liquid you are using.
- The caustic solution is best prepared in an area that is well ventilated, and yet protected from drafts. The kitchen sink is OK is you have plenty of air circulating in the kitchen. I prefer to mix the caustic solution outside, next to the garden faucet - and I make sure there are no winds or drafts that could blow the dry alkali around.
- Beginner soapmakers will find it less traumatic to approach soapmaking using simple recipes, where the caustic solution is made with water. As you get more experienced, you can substitute part or all of the water with other liquids, such as herbal teas, milks etc.
- The water for the caustic solution must be cool (<20ºC / 68ºF). Never use warm water to dissolve the alkali!
- When you add the alkali to the water, a chemical reaction occurs, which generates heat... and quite a lot of heat, for that matter! The temperature of a standard strenght caustic solution for bar soap (27% sodium hydroxide, 73% water) will easily reach 80ºC / 176ºF or more.
- KOH (potassium hydroxide), which is used to make liquid soap, heats the liquid up even hotter and quicker than NaOH, and has an amazing tendency to "boil over". When diluting KOH, it is recommended to always keep the container with the liquid inside a larger container filled with cold water, and add the KOH a little bit at a time, stirring without interruption. Also remember that diluting KOH usually requires more liquid than diluting NaOH.
- The dry alkali is best added to the water in a slow continuous flow, while stirring with the other hand. If the solution gets too hot too quickly, stop pouring the dry alkali and let the solution cool down slightly before adding the rest. While waiting for the temperature to go down, cover both containers with their lids.
- While preparing the caustic solution, avoid breathing in the vapours. If you can't get the alkali to pour in a slow continuous flow, prepare the solution by mixing in a little bit of alkali at a time, stirring well to dissolve it completely and covering the containers until the next "go".
- If, in spite of all precautions, you get some caustic solution or fresh soap mix on your skin, wash with plenty of cold water and apply some vinegar to the skin. Vinegar is acidic, and will help balance out the alkalinity. You can use lemon juice if you don't have vinegar on hand - but it is always recommended to keep a bottle of vinegar handy when making soap.
- The soap mix is highly alkaline and will burn your skin if you touch it before the saponification reaction has completed (this usually happens when the soap is set). Avoid touching freshly made soap with bare hands.
For further information on soapmaking, you might like to also read through my soapmaking methods and the soap making resources section.
Learn how to make soap
Order our soap making book
Meet other soapmakers
Australian essential oil properties
Soap moulds, soapmaking molds
Natural soap & shampoo recipes
Eco-friendly household cleaners
Teach yourself soapmaking methods
Soapmaking mailing list
DWCP: Discounted Water Cold Process
sapone naturale, sostenibilitÓ, ecologia domestica, cure naturali per la pelle...
Natural handmade soap
Soap supplies Australia
Soap mailing list
Soap Naturally book