AuwaEarth

07/06/2026

04/06/2026

04/06/2026

04/06/2026

🌿We have been invited to share all things earth building at the World Environment Day festival - happening this Sunday, see you there!

15/05/2026

5 Things You Didn't Know About Earthen Floors...

https://mudwoman.substack.com/p/5-things-you-didnt-know-about-earthen

01/03/2026

15/01/2026

is a technique for compressing (burnishing) and sealing lime plaster. It was first developed in Morocco to line cisterns.

It works because of the chemistry...which is as follows:
1. Inert lime found in nature, chemically CaCO3 (calcium carbonate, limestone, marble, etc.) is heated → this creates CaO (quicklime, calcium oxide, highly reactive with water) + CO2 (which escapes into the atmosphere)

2. Water (H2O) is added to the calcium oxide (CaO) in a process called slaking → The result is chemically Ca(OH)2 (calcium hydroxide, which is reactive with carbon dioxide) + intense heat! This process requires a lot of safety gear. (Note that adding water to powdered Ca(OH)2 is re-hydration, not true slaking)
This is what is used to make plaster!

3. On the wall, the calcium hydroxide, chemically Ca(OH)2 re-absorbs CO2 from the air → becoming the exact thing you started with: CaCO3 (closing the carbon cycle and returning to calcium carbonate)

4. For tadelakt, there is one extra bit of chemistry, used to create an integral wax sealer in the surface of the lime. For this reaction, soap is applied in thin layers to the surface of the compressed lime. The unreacted calcium in the lime (Ca) and stearic acid in soap have a chemical reaction → creating calcium stearate (common waxy binder; basically really beautiful soap scum)

And TADA! You have a beautiful sheen and a water-repellent wall.

11/11/2025