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Wood Ash Lye: Making It at Home and Using It as a Natural Detergent

Discover the age-old technique of creating wood ash lye, a classic and simple natural detergent deeply rooted in our cultural heritage. For centuries, homemakers have used it for laundry and general cleaning. Learn how to craft it at home and explore its eco-friendly cleaning applications.

by BioGrow

The wood ash lye has been an integral part of our folk culture, serving as the most classic and straightforward natural detergent. For centuries, homemakers have used it to wash laundry and for general cleaning purposes. Its preparation process is relatively simple, although there are several variations and elaborations, reflecting the ancient art of soap making.

In this article, we focus on the basic preparation of wood ash lye. This method is suitable for anyone with a fireplace or a wood-burning stove. We have already explored how you can use wood ash as fertilizer for your garden; today, let’s see how it can transform into a perfect eco-friendly detergent.

How to Make Wood Ash Lye


Lye is a liquid solution obtained by treating wood ash with boiling water. Among other substances, ash contains sodium carbonate and potassium carbonate, both elements with significant degreasing effects. For the classic preparation, you need just two simple ingredients (in specific ratios):

  • 1 part wood ash
  • 5 parts water

This ratio must be maintained in volume, not weight. To help with the right quantities, a regular kitchen glass can be used. The ratio would be one glass of ash and five glasses of water, or two glasses of ash and ten glasses of water, and so on.


First, sift the wood ash, perhaps using an old colander. This process yields a fine powder, free of charcoal or partially incinerated particles. The sifted ash should be placed in a pot, dedicated solely for this purpose (avoid using aluminum pots).
Next, add water and bring it to a boil over low heat, stirring repeatedly. Once it reaches a boil, stabilize the mixture by lowering the flame slightly. Continue cooking, stirring occasionally, for about two hours.
Avoid overcooking, as excessive evaporation can occur, leading to a too strong and slightly corrosive lye. After the two hours, turn off the heat, cover the pot, and let it rest without stirring for 24 hours.
The next day, the ash will have settled at the bottom of the pot, forming a rather thick layer. The water, on the other hand, will have transformed into lye, appearing golden and sitting on the surface.
The final step to obtain the ready-to-use product is filtering. This is done using another pot (or a container) where a fine-mesh sieve is placed. On this sieve, a cotton cloth is arranged to enhance the filtration. Carefully pour the solution into the sieve, trying not to disturb the ash deposit in the other pot.
The resulting lye is left to settle to check if more ash deposits at the bottom. If this happens, repeat the filtering process. When the lye is clear and transparent, it is ready to be used or stored.

Storing Wood Ash Lye

From the preparation process, we obtain two products: the actual liquid lye and lye paste. The paste is essentially the creamy ash residue left after filtering.
These products have no expiration date, and their degreasing effectiveness remains unaltered for years. It’s advisable to prepare a substantial quantity, store them, and use as needed. Liquid lye can be stored well in glass bottles (some suitable options can be found here). The paste can be stored in a plastic container with a tight seal (similar to an ice cream container).

How to Use Wood Ash Lye

Both products derived from ash processing can replace commercial detergents. Let’s see how.

Liquid Lye

Liquid lye is excellent for washing dishes. Simply add about 50 ml to the washing water. It’s highly effective against stubborn stains and dirt. Moreover, it’s perfect for cleaning floors. In this case, adding a bit to the mop bucket is sufficient. Keep in mind that the liquid is highly concentrated and should not be used on certain materials, such as wood. Another usage idea is to fill a spray bottle with this liquid and use it as a degreaser. Liquid lye can also be used to wash laundry. It works well in washing machines, in hot washes, similar to bleach, or in handwashing.

Lye Paste

Lye paste, on the other hand, has a more limited scope. Its application is confined to washing pots or copper objects, especially when they are very dirty. In this case, simply apply a small amount to the sponge. Traditionally, lye was also used as a personal cleanser. However, it was heavily diluted before use. For instance, it was used to rinse hair. This washing was done at most a couple of times a month.

Tips and Conclusion

When using lye, it’s advisable to always wear gloves. Despite being a natural product, this substance can be harsh on the skin. Furthermore, we recommend using this product instead of commercial detergents, which, besides being costly, heavily pollute our already fragile water sources.

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