How to Make Lye from Scratch

So, you're wondering what's involved in making lye from scratch? Here's a quick rundown of what you'll need to make it work.

Please, remember to take all the normal precautions when working with lye. This goes doubly for making lye - since you'll be moving around unknown concentrations of lye.

Equipment Needed for Lye Making:

  • A large, non-reactive container.
    Water will pass through ashes and straw in this container, to leech the lye from the ashes. Good options include a waterproof wooden barrel or a heavy-duty plastic bucket. No aluminum, please, as lye reacts with aluminum. We will call this the "lye making container".

  • Two more non-reactive, lye-proof containers.
    These will catch the lye as it drips out of the lye making container.

  • Rocks or gravel

  • Straw or Hay
    The straw acts like a filter. It lets the lye-water pass through, while stopping the ash.

  • Hardwood ashes.
    These must be hardwood ashes, not soft woods, or you won't get usable lye. The ashes should be completely cool before using.

  • Soft water.
    This could be rain water, distilled water, or water from a dehumidifier. Tap water will work fine if you have soft water. Hard water (water with a high mineral content, making it difficult to work up a lather with soap or shampoo) won't work.

Steps to Make Lye:

  • Make sure your lye-making container is:
    • » Lye-proof and non-reactive.
    • » Clean.
    • » Water-proof with no leaks.

  • Drill small holes in the bottom of the container, like those in flowerpots, that will allow the lye water to drain out.

  • Place a layer of rocks (1-2 inches) on the bottom of your container. This will prevent the straw (to be added) from clogging the holes.

  • Place a thick layer of straw on top of the rocks. The straw will act as a filter, allowing the lye to pass through, but blocking the ash. Remember, the lye will eat away at the straw, so it needs to be replaced every time you make a new batch of lye. Use gloves to avoid coming in contact with lye on the straw!

  • Fill the rest of the container with ash, leaving an inch or two of clearance at the top.

  • Next comes the tricky part. You need to find something that will hold the lye container up, off of the ground so that the water drips out of the bottom. It MUST be stable - lye is dangerous, you do not want to risk it tipping over!

  • Once your lye container is raised and stable, place one of your alternate containers under the lye container, so that it will catch all of the lye water that drips out of the bottom.

  • Slowly and with great care, pour the water over the ashes. The water will drip through the ashes, through the straw, through the rocks, and eventually, out of the holes at the bottom of the container and into the second container. It should be a reddish-brown.

  • When the dripping stops, you'll want to remove the container that now contains fresh lye-water, and place the second container under the lye making system. This will catch any stray drips.

  • After one pass, the lye-water is likely not strong enough for soap-making. You'll probably need to repeat the process at least two more times, or more. With the empty bucket under the lye making container, slowly and carefully (very carefully!) pour the lye-water back over the ashes.

  • Repeat the process of switching the containers and pouring the water over the ashes several times.

  • You can test the strength of the lye-water by dropping an egg in it. If the egg nearly floats (a tiny amount should just peek out over the surface of the lye-water, about the size of a quarter) - then the lye-water is ready to use.

    If the lye-water is too strong (the egg floats much higher than described), you can "water it down" by adding a small amount of plain, soft water. If the lye-water is too weak, you can continue to run it through the lye making container several times over the course of a few days. If that doesn't work, you may have used too much water for the amount of ashes you had... if you can clean out the system and reset it with new ashes, you can run the water through those to strengthen it. Or, some people suggest you can boil off some of the water in the lye-water solution, and strengthen it like that.

    If you attempt to boil off the water, please be careful. Be sure to use a lye-proof pot that you will NOT use again for food.

After you've gone through this, you should have a strong enough batch of lye to make your own soap.