Homemade Lye From Wood Ash

What is Lye?

Lye is a key ingredient in soap making.  It is a strong alkali or base substance which reacts with fat to form soap.  You can buy lye in the form of caustic soda (sodium hydroxide) or you can make your own homemade lye in the form of caustic potash (potassium hydroxide).

Firstly lets get the health and safety stuff out of the way.  All lye is extremely corrosive.  Keep your skin covered, wear goggles to avoid splashes to eyes and definitely keep all lye out of the reach of children and pets.  It can be fatal if swallowed.

There, let us proceed…

Lye water can be made at home by leaching water through wood-ash.   If you want to do this on a large scale you will need barrels and filters and taps and so on.  Here we’re creating homemade lye water on a small scale using what we have to hand.  Let me explain:

lye-bucketMaking Lye from Wood Ash at Home

  • The wood ash should come from burning hardwood.
  • Find yourself an old bucket into which you’ve created a few small drainage holes.
  • Put a layer of old straw in the bottom of the bucket.
  • Now half fill the bucket with wood ash.
  • Put your bucket into a larger clean bucket to collect the lye water.
  • Pour on some water.  Rainwater will keep the whole mixture soft and chemical free.
  • Collect the water which leaches through the wood ash, and pour it back over to leach through again.
  • Repeat this at least three times over at least three days.
  • The resulting liquid will be lye water!

lye-waterNow the concentration of this lye water will depend on how much water and ash you used as well as what type of wood the ash came from.  I am no scientist, we just wanted some lye water.  If you need something precise buy some caustic soda as it will tell you its composition on the pack.

But, we can tell if the lye water is the right strength for use in soap making:

Calculating the Strength of Homemade Lye

To check your homemade lye is strong enough to use  in soap making at home:

  • If a chicken feather dissolves in the lye it is strong enough.  If not put the water back through the wood ash to get more concentrated.
  • If a fresh egg sinks the lye water is too weak.  If the egg floats almost on top of the solution the lye water is too strong and will need to be weakened with additional water.  If the fresh egg floats near the top of the solution with a little lye water above it you’ve got a perfect lye water for soap making.

So to make lye at home  is a pretty simple process.  But that is so long as you don’t mind a ‘rough and ready’ approach to making lye!  We think it’s always good to try out free ways of doing things.

Remember homemade lye from wood ash will give a softer soap than that made with commercial caustic soda.  We have followed similar recipes for homemade olive oil soap with both commercial caustic soda and homemade lye from wood ash.  The wood ash lye soap is a liquid soap which will be good as a hand-wash and hopefully shampoo too.  The caustic soda olive oil soap on the other hand is drying hard and will be a general bar of hard soap.

If you have lots of wood ash, making your own homemade lye is a great way to use some of it up!

For a more self sufficient future

17 Responses to “Homemade Lye From Wood Ash”

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  1. Kristin says:

    Thanks for this info! We’ve talked about doing it and know how “in theory”. It is nice to know someone who actually did it! One of these days I’ll get around to making our own soap!

  2. Kristin – it seems very odd to have made soap from something so ‘dirty’ though!

  3. Kristin says:

    I didn’t mention that I planned on making soap from home rendered tallow & lard from our own animals one day. So not only would we be rubbing our bodies with something that looks “dirty” to start with, but also with dead animals. It all seems strange…but that’s how it works.

  4. Almostgotit says:

    Hey! Something Great to Make out of all our wood stove ashes! We’ve been making lye water without meaning to, leaving buckets of ash outside to cool and then having it rain. Probably should be more careful with it, then, aye?

    Thanks for the great tip!

    Almostgotit’s last blog post..Laundry and Spring Break and Blogging, Oh My

  5. Gary Dill says:

    Why do you boil the lye water down to crystals , then add water back in before using to make soap? You have the right strength if it floats the egg,why not use a measured amount of the liquid?

  6. gela says:

    i burn wood all winter to heat my home..i put the ashes mostly on my garden.. we have for generations… the rain goes thru these endlessly.. at what point.. rainy day can i figure this has turned into lye on the land ?? eventually the rain will delute the lye… my great grandparents had their garden under the ashes & lived into their 90’s & so on thru the times..& the garden grows like anyone elses normally.

  7. janette dym says:

    how much homemade lye is used in oil to make the soap


    homemade lye +?

    do you need to heat the oil and the lye to temperature? could some one please tell me I have made homemade wood lye but i need the total amount thanks !

    • Janette,

      The method and ingredients for homemade soap may be found here http://aselfsufficientlife.com/homemade-soap.html

    • Lot says:

      In the old days they used high numbers of the ingredients. So you need to figure your amounts out. The recipe calls for 12 pounds tallow and uses 4x 5 gallons lye water. It requires some time on a burner. You melt the tallow and add the lye. If a thick scum of grease forms on top, that means you need more lye. If the soap does not thicken and no scum appears you need more fat. You know when it gets done, when no more froth rises to the top. When large white bubbles pop to the surface remove from the heat and let cool. Test: with a clean knife lift some soap over a plate. If the soap turns whitish and falls in small pieces, there is too much lye in it. If the soap falls in long ropy pieces, it needs more lye. When you think it is really done, you put a blob of the soap on a plate. If it cools transparent with whitish streaks and specks, it is done. If it turns out greyish, it needs more lye. If it has a grey skin over the top too much lye. Hope this helps you some way.

  8. l taylor says:

    Does this lye work with making hominy also?

  9. saramonster says:

    I LOVE this site!!!! It is so straighf forward and to the point and has so many helpful comments! We are working on self sufficiency at my house and it makes a world of diference to get great tips from real life experiences. Thanks so much! Now on to our first butchering of chickens! lol

  10. marti says:

    No mention is made of the material your tools need to be made of. For instance, lye eats aluminum. So, watch out with your buckets, etc.