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How to Lye (potassium hydroxide).

This post is going to cover how to turn hard wood ashes into useable lye for dirt cheap.

Your ancestors made and used lye in their everyday life. Now you have a limit on how much lye you're legally allowed to buy.

Below is a photo of a man making lye while his wife melts fats to produce soap.

Man making lye water while his wife melts fats to make soap.

You can use lye to:

  • Make Soap.

  • Clear a Drain.

  • Start a fire.

  • Make bagels, authentic pretzel, green olives, Nordic lutefisk, century eggs, and many other traditional dishes.

  • Extract metals from stone.

  • Green burial.

Ancient Mesopotamians left clear directions on how to use lye water to produce soap.

Romans and greeks didn't use soap on themselves, rather olive oil, but they did use soaps to wash animal furs before spindling into blankets or clothes.

Pliny the Elder’s, a roman scholar, wrote a booked called,Naturalis Historia” from A.D. 77. In this book it describes using a tallow pomade made from lye water that Gauls, particularly the men, applied to their hair to give it “a reddish tint.”

Authentic Laugenbrezeln—or soft pretzel has always been made with lye water.

There's many ways that lye was used in common everyday life. We still use lye in many products to this day.

*** Before we even start I need you to understand how dangerous lye it. ***

Lye works in soap because it uses the fat in a process called "Saponification." Lye cleaves the ester bond in fats, releasing fatty acid salts (soaps) and glycerol.

Essentially turning excess fat into soap. If there's not enough fat to finish the process, it will still search for fats. This is why you always wait for soap to finish curing before using.

*** You have fat in your skin.

Lye will burn your skin off if you use it incorrectly. ***

You cannot use water to get lye off, it actually makes it worse. Use vinegar.

How To Make Lye:

The process of turning ashes into lye is called leeching. Thus we will be making a leeching barrel. It's easy and safe, if done correctly.

Essentially you will need three vessels to hold the water. One on top, which will be layered with various materials. One other will be below. It will collect your lye water through a drainage hole. The last vessel will be used to pour the water into the system.


1.) Large, non-reactive barrel/container (not aluminum).

2.) Two more non-reactive water vessels (also not aluminum).

3.) Rocks or Gravel.

4.) Straw or hay.

5.) Hardwood ashes (needs to be hardwood).

6.) Soft water (rain or distilled). It MUST not have metals/hard minerals in it.

7.) Gloves


  1. First you need to make sure your leeching vessel is clean, water proof, and obviously not going to react to lye.

  2. Figure out a way to drain water where you want from the vessel. You can use a flower pot, or put a drainage tube. You just need to make sure your bottom vessel can catch the liquid.

  3. Place 1-2 inches of rock at the bottom of the barrel. You don't want the straw to clog the drainage hole.

  4. Place a thick layer of straw or hay above the rocks. This layer prevents the ash from just washing out. You'll need to replace this as the lye will eat it away.

  5. Fill the rest of the barrel with hardwood ash. Leave 2-4 inches of room at the top for water.

  6. Position your leeching vessel high up enough to drain into your drainage vessel. Take time to make this secure, you don't want it to spill.

  7. Once everything is in position, slowly pour your water into the vessel. It should slowly drip out a red/brown liquid. Wait for it all to drip out.

  8. You'll need to run the water through the leeching barrel a few times.

How to test your Lye:

The easiest way would be with a PH strip. Lye sits at 14.

However, you might not have a PH strip so you can just use an egg.

"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."

That's all there is to it. Give it a go the next time you burn some hard wood, save yourself the need to buy lye ever again.


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