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Wood ash can be obtained by sieving the remains of burnt, non-treated wood. The composition and amount of the ash will depend on the type of combustion (higher temperatures will lead to fewer ash residues). Normally, remaining ash will represent 0.43 — 1.82% of the initial wood weight.

Although poor in nitrogen, wood ash is a source of calcium carbonate (30-40%) and potash (10%), so they have long been used in agricultural soil and composting as a liming and deacidifying agent.

But wood ash has a number of other possible uses at home. Some of them are:

Wood insect repellent:

Mix ash with water in a jar, and let it sit for a week. After that, apply it to raw wood to act as an insect repellent. You could also combine it with an oil-based mix of insecticide plants such as spicy paprika, chili or thyme.

Polish, abrasive cleaner:

Dry ash can be used to remove embedded dirt, for instance the glass inside a stove’s door, or a frying pan.

After preparing wood ash lye water (see below) the solid humid residues make a perfect polishing agent. If careful sieving was done before preparing the lye water, you won’t need to fear damaging or scratching metal surfaces. As you start to clean you will think you’re only making everything dirtier, but you’ll get surprising results after rinsing the ash off.

Maybe not that much…

Wood ash lye water:

Although this is softer than normal lye water, protective gloves and goggles could be useful.

  1. Pour the ashes through a sieve to remove charcoal. Alternatively, we could let the ash sink in water and remove the charcoal with a strainer. The whiter the ashes, the better detergent we will get. The harder the initial wood, the stronger the final lye water.
  2. Mix ashes with 4 or 5 parts of hot water (or in sunny weather, simply let them sit in a metal bucket outside for a few days. This is what my Grandma did.)
  3. Stir it for a few minutes and cover the bucket with a cloth or a lid for one or two days. Make sure you stir again at least once during this time.
  4. After that the ashes will be at the bottom of the bucket, and the lye water will remain on top. Pour this soapy solution into a different container (be careful enough to label it properly!). The ashes can be used to polish metals, as indicated above.

If you want to do this more than a few times, you might want to see what these guys did:

Ash can be used with new water for another cycle, until they yield no more “soapy water”. Then they can be safely composted (although they will still raise the pH). Lye water should not be applied to plants, since it will burn them.

Lye water or potash water can be used to wash vegetables, cooking utensils, glass…. Some people use it as a body and hair cleaner, and even as an ingredient in toothpaste. It is also used for washing clothes and removing chemicals from commercial natural fibres such as cotton, bamboo and hemp (notice that tinctures responsible for the colour are chemicals too).

To be used as a liquid detergent, lye water can be diluted in a proportion of one cup of potash lye to four litres of hot water. High concentrations will make a stronger, more aggressive detergent. Dilutions will have washing power as long as the solution keeps feeling “soapy”.

To wash natural fibres, they can be placed in a cooking pot and covered with potash water. Then water is heated to boiling temperature and maintained for 2-3 minutes, while continuously stirring. After that time we remove the material and rinse it with cold water.

For natural, less aggressive ways to wash our fibres, other methods can come handy, for instance the boiled roots of the wild (invasive!) plant Saponaria officinalis (soapwort) are still used by museum conservators to wash delicate cloths.


10 Responses to “Domestic Uses for Wood Ash”

  1. Bob Burns

    Ash also makes a pretty good general purpose dust for repelling insects and animals from plants. For insects, I’ve found that a blend of 25% D.E. (diatomaceous earth) and 75% ash is as effective as 100% D.E. and saves money and footprint on this purchased input.

  2. Jason Gerhardt

    Certain types of wood ash (mostly that from maples and other hardwoods) was used to nixtamalize flour corn to make it more digestible. When European settlers arrived in North America they brought their grain mills with them and simply ground the corn into flour, ridiculing the indigenous preparation method of treating corn with wood ash. Little did they know they weren’t digesting the corn completely, which was causing a niacin deficiency leading to pellagra. This is yet another significant and in need of revival use for wood ash.

    Cool article! Love the thinking of finding more uses for common so-called “waste products”.

  3. Gabriela

    I forgot to say, I also read that lye water can be also used to whiten recycled paper.

    I hope that you can put these tips to good use!

  4. Juan Manuel Burgos

    Awesome resource mother nature gives us, showing once again that no chemicals must be involved at all in cleaning anything we want :D

    Question: does anybody know how to make soap using potash water instead of sodium hydroxide (caustic soda)?

  5. Elaine Codling

    Cleaning the glass face of your wood stove is dead easy and doesn’t require any preparation of the wood ash at all. Just dampen a bit of newspaper and dip it into the cold ashes and rub it onto the cold glass face. It doesn’t even need scrubbing.

  6. Deano

    You can also cure olives with lye made from woodash there are directions elsewhere on the net

  7. Brian White

    People in Vancouver have used wood ash lye to eat away the soft organic stuff and get the fibres out of broom in a demo project. Apparently they have used broom that way in Italy for a few thousand years! I am part of a flax to linen project but I don’t know if the same thing can be done with flax.
    I have also checked out a website where they are working on nettle fibre. People may have forgotten the technology because it says you cannot use the same rotting techniques that work with linen on nettles. Maybe the lye would work on them too? Brian

  8. Sonya Linette

    Wow! Thank you so much for sharing this. I knew ashes can be use for cleaning but I never knew the details. Amazing!


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