Used in bushcraft, off-grid homesteading, or survival situations to create natural mortar, sealant, or plaster for primitive construction, cooking infrastructure, and water catchment systems.
Calcium hydroxide (hydrated lime) has been used for centuries in lime-based plasters and mortars. When combined with sand, clay, and water, it forms a durable, breathable material that can be applied to natural structures like cob ovens, earthen shelters, and stone or clay walls. In survival or low-tech building scenarios, it offers a reliable way to reinforce, seal, and protect surfaces using only basic tools and materials.
Ingredients
- Calcium Hydroxide (hydrated lime): construction or garden grade
- Fine sand: clean and dry
- Clay-rich soil or pure clay (optional but traditional)
- Clean water
- Mixing container (non-metallic)
- Trowel, stick, or flat-edge tool for application
How to Use It
- Mix 1 part hydrated lime with 2–3 parts fine sand (by volume)
- Optionally add 1 part clay-rich soil to improve adhesion and texture
- Slowly add clean water and mix until a smooth, paste-like consistency is reached
- Use immediately to plaster walls, patch cracks in cob ovens, seal masonry joints, or line small water catchment features
- Apply with a trowel, stick, or by hand
- Allow to cure and dry for 24–72 hours depending on thickness and humidity
- Reapply as needed to build up layers or reinforce exposed areas
Warnings
- Wear gloves, eye protection, and a dust mask when handling dry lime powder
- Do not apply on metal surfaces: lime is corrosive to metal
- Avoid using in wet conditions or where water will pool unless the surface is properly cured and sealed
- Not suitable for structural load-bearing use without reinforcement
Storage & Shelf Life
- Store calcium hydroxide in a tightly sealed container in a dry, cool area
- Keep away from moisture, air exposure, and acids
- When stored dry, shelf life is indefinite
When to Use Lime Mortar or Plaster
- Building or maintaining cob ovens, rocket stoves, or earthen cooking structures
- Sealing cracks or joints in off-grid shelters, walls, or cisterns
- Lining interior walls of root cellars, clay basins, or food storage areas
- Making small-scale water catchment or clay-lined filtration setups
- As a traditional, renewable, and accessible building material in grid-down scenarios