Aged lime, also called soaked or matured lime (Dutch “gemenageerd”), is quicklime that has been slaked and then kept submerged under water for weeks, months or even years until it becomes fully hydrated, smoother and highly workable.
When quicklime (calcium oxide) reacts with water it forms calcium hydroxide, a process known as slaking. If the resulting lime putty is left to mature under a layer of water, any remaining unslaked particles continue to hydrate and the material develops a fine, buttery, plastic consistency. This maturing prevents later expansion in the finished work and produces a mortar or plaster that spreads evenly and adheres well.
Why lime is aged
- Complete hydration: all quicklime grains are slaked, avoiding disruptive “blowing” once built in.
- Improved workability: the putty becomes creamy and easy to spread with a trowel.
- Finer particle structure: longer maturing yields a smoother, more cohesive material.
- Better durability: well-aged lime carbonates slowly and forms a strong, breathable matrix.
Application
Aged lime is prized in traditional and restoration work where authentic, breathable materials are required.
| Use | Purpose |
|---|---|
| Lime mortar | Bedding and pointing historic brick and stone |
| Lime plaster | Smooth internal renders and finishes |
| Limewash | Breathable decorative surface coating |
It is especially valued in monument restoration, where compatibility with old masonry is essential and hard cement mortars would cause damage.
Related terms
- lime
- lime mortar
- mortar
- masonry
- hydration
Looking for more DIY plans? Check out fredsdiyplans.com.