The problem with making lye from wood ash, although it is a simple process, the end result can be that your lye water is either too strong, or too weak. Either way, it could spoil your batch of homemade soap.
Having said that, none of our ancestors had access to commercial lye and they made soap just fine. We will also give you a couple of tests to do that will take a lot of the guess work out of the process, making sure that your lye is of the right strength.
The ingredients for making lye are wood ash and water. Preferably rain water, as it is soft, although tap water will work just as well. The ash should come from hardwoods as soft woods are too resinous to mix with fat.
To make lye and be successful at soap making your lye has to be at the right strength. Now there are 2 ways in which this can be done, both of which indirectly involve chickens. If you live on a farm and keep chickens, then this test is fine for you. If not, then you can use the second test.
This is a simple test. Take a chicken feather and place it in the lye. If the feather dissolves, the lye is strong enough and you can use it for your soap. If not, you will have to re-boil the lye water when it emerges and repeat the process until your chicken feathers dissolve.
This test involves using a fresh, whole egg or a potato works just as well. Take the egg or potato of similar size and place it in the cold lye water. If it sinks, your lye is not strong enough and you will have to repeat the process until it does.
If the potato floats with just a little of the lye water above it; about an inch showing above the water, or the head of the egg sinks to just half-way down, then the strength is just right. If the potato or egg floats too high, almost on top of the lye water, then the strength is too strong. You can compensate by adding a little bit of fresh water to the lye water and try again.
With the first test, I would still back this up with the "egg floating" test, just to make sure that my lye water was not too strong.
Boil water half of the capacity of the bucket and pour gently over the ashes. As soon as the water makes contact with the ash it will start hissing and bubbling. This is perfectly normal.
You may find at this stage that the water is just sitting on top of the ash, without it appearing to do anything. Just leave it, without disturbing it, and come back later to see when you can add the rest of the water.
Once you have used all the water elevate the bucket so that you are able to place a glass or plastic container under the hole that you previously drilled and stopped up with a nail. Place your receiving container under the hole and remove the nail. Do not expect lye water to come out of here. This could take hours, if not days.
Once you have enough lye water use the nail to stop up the hole. Take the lye water to the kitchen and boil carefully.
Take care at this stage as the lye is caustic and if it splashes onto your skin and into your eyes it will burn. You will need ot wear gloves and safety glasses at this point.
Once you have heated up your lye water take it back to your bucket and carefully pour it back over the ashes in the bucket. This helps strengthen the lye.
Wait for the lye to emerge once again.
When you buy commercial lye it is in the form of crystals. When you make lye at home you will want your lye to be in crystals too. This is very easy to do. Take your lye water and place it in the sun until the water has evaporated. What you are left with are your lye crystals that you can use quite happily in your soap making recipes.
In the end your homemade lye is softer on the skin. It is potassium hydroxide as opposed to sodium hydroxide. When following soap recipes make sure that you use the right type of hydroxide, as although both are lye, they cannot usually be used in place of the other in certain recipes.
The potassium hydroxide molecules are larger than the sodium hydroxide molecules. It is this size difference that enables the potassium hydroxide to maintain a liquid state.
Potassium hydroxide is normally used to make liquid soaps. And when our ancestors made soap using homemade lye, most of the time they ended up with liquid soap because the lye they were using wasn't strong enough.
However, you can make a hard soap by adding common salt at the end of the boiling process. If you want to add salt to harden your bars of soap, weigh out the water you are going to mix your lye with.
Before you add the lye, add ½ tsp. of salt per pound of oil/rendered fat in your recipe. Stir well to make sure that all of the salt is dissolved. Add your lye to the salted water, making your lye solution, and resume your normal soap making procedure. Both types of hydroxide, however, are extremely corrosive and must be handled and stored with care.
The traditional ratio is 2 pounds fat or grease (such as bacon fat) to 1 gallon homemade lye.
Place the fat and lye water in a large
pot suitable for soap making (not aluminum) Add the vinegar mixed in
with the water. Keep on a rolling boil
until thick and slimy. This can take several hours.
If at this stage you want to use it was soft soap it is ready after straining through several layers of cheesecloth before placing in storage containers. 1 cup of homemade liquid soap per load is all that is needed.
If you want hard soap you will need to add 1 teapoon salt dissolved in a little water to the mixture at this stage and boil for longer. Skim the foam off the top and place the liquid into molds and allow to set.
Visit our Making Soap page for more information on how to make soap at home. You will also find Soap Recipes for the three main types of soaps; hand-milled soaps where you do not have to use raw lye, cold process and hot process soaps.