Turning hardwood ashes into homemade lye for soap or stripping animal hides is really easy and is just as effective as the commercially produced product. There is a difference in the two; homemade lye is Potassium Hydroxide (KOH) while commercial lye is Sodium Hydroxide (NaOH) and you’ll need to keep that in mind if you are converting a soap recipe or making up a new one. Potassium Hydroxide, homemade lye, typically makes a softer soap, but personally I don’t think it’s all that noticeable if you’ve cooked it down to the correct strength and amend it with a little salt. To make homemade lye, you’ll need ashes from any hardwood tree or combination of trees (softwoods are too resinous), water and a suitable pot. There are several ways to leach the lye water from the ashes, but with all our animals and a 5 year old running around, we use a more contained method than the conventional warm water drip way. It’s just safer for everyone involved.
Getting started:
Utensils =
*Large pot that is either stainless steel, glass or has a porcelain coating. Lye water will corrode aluminum. I use one like this: Enamel Stock Pot , but before you drop $25 on a new one, surf around the junk shops. They usually have one or two that are too dinged to cook food in, but are perfect to designate as a lye pot. That’s were I got mine.
- Long handle wooden spoon
- Wooden or plastic ladle
- Large glass jar to strain into
- Coffee filters, loose weave muslin or cheesecloth
- Rubber band to hold filter in place
- Wooden skewer, chopstick, popsicle stick or something similar and a marking pen
- A raw egg
- Long sleeve clothes and/or rubber gloves
Ingredients =
- Hardwood ashes
- Water
**In this example, we used 24 cups of ash and 32 cups of water. Once finished, it produced a quart and a half of correct strength lye water. It doesn’t really matter how much you use, just make sure you start with an equal amount of ash and water then top off with enough water to give you about an inch more on the top.
1. In a well ventilated area, put the ashes and water into the pot and bring it up to a boil. You will need to stir almost continually to keep the ashes from forming into a thick layer in the bottom of the pot. It’s important to stir carefully and not slosh the lye water. It’s not in near full strength form yet, but is still something to be respected. Once it reaches boiling, turn off the heat and let it sit until cool. I periodically stir mine while it’s cooling, but I’m not sure if that actually helps the strength of it or not.
2. When the mixture is cool, use a ladle (wooden or plastic) to carefully dip out the water in the top of the pot. Take care not to disturb the settled ashes too much and you won’t have a ton of junk to strain out later.
3. Place your coffee filter, muslin or cheesecloth over the mouth of a large jar (I use a gallon jar) and secure it with the rubber band. Make sure you have a significant amount of the filter hanging down inside the jar. Carefully ladle the lye water into the jar. You will have to ladle it instead of pouring because it will take a while to seep through, especially if using a coffee filter or piece of muslin. You will also probably need to do more than one batch to filter all the water.
4. Once you’ve filtered all the lye water and discarded the left over ash, rinse the pot out well and put the filtered lye water back in. If you’re like us and have animals free-ranging, you may want to bury the left over ash to keep everyone out of it. Some of our animals are smart enough to stay out of it, and others I’m not so sure of. 
5. Using the stick, mark the height of the water, then mark a 1/2 way point and a 1/4 way point. You will need these markings to know when to test the strength of the lye.
6. Simmer the lye water to reduce it, periodically checking the level with your marked stick. Once the water has been reduced to 1/4, carefully dip out a couple of cups and let it cool. Once the lye water is cool, use your stirring spoon to place the raw egg into the lye water. If the lye is the correct strength, the egg will float enough to have a quarter size spot of it above the water line. If it doesn’t have a quarter’s worth showing, remove the egg and return the lye water back to the pot to reduce some more. You can reuse the egg as many times as you need until it floats correctly, but be sure to discard it once your done, it’s no longer safe to eat.
When you’ve finished, keep your lye water in a glass or ceramic jar, using plastic wrap to keep the lye from having contact with any aluminum parts of the lid. As you can see below, you’ll have significantly less in the end that you did when you started!
The lye water keeps well, I’ve kept it for a full year and had good soap from it. Also be SURE to label it REALLY well. I used the jars here to be able to show the end volume, but it’s better to keep it in something that won’t be as easily mistaken for food by someone who doesn’t know what it is. It looks very similar to chicken broth. Dirty chicken broth… but all the same, it’s better to be safe than sorry. You could also continue reducing it until you have crystals that you would reconstitute with water, but I have only tried that once and the lye gets quite volatile.
Update on 12/9/16: For anyone who is interested, the wood ash lye soap recipe has been posted, finally! You can find it here: Make Your Own Wood Ash Lye Soap