Fractures are opened and prepped to be repaired with lime putty
Lime Plaster Benefits
Lime plaster has many benefits but the most impressive are its breathability and flexibility, making it the choice for conservation. In a modern building where there is little movement, flexing or shrinkage, most modern plasters are fine. But, with older properties that may have many different materials and specifications, lime can be more forgiving.
Lime plaster is permeable and allows for the diffusion and evaporation of moisture, which easily passes through and will not soften or dissolve like drywall or gypsum plaster. Cement based plasters will trap and prevent moisture from escaping, leading to a greater problem - gradually building and then ultimately forcing the moisture to come out elsewhere.
While cement based plasters and renders are strong in compressive strength, they lack greatly in flexibility. Any movement can result in the plaster cracking. When buildings plastered with lime are subject to small movements, they are more likely to develop many fine cracks than the individual large cracks which occur in cement based buildings. Moisture penetration can dissolve the ‘free’ lime and transport it into these very fine cracks. As the water evaporates, this lime is deposited and begins to heal the cracks. This process is called autogenous, or self healing.
The alkaline properties of lime are naturally bacteria repellant.
Haired lime plaster on a barrel vaulted ceiling during a recent restoration project
Reinstating a wall after renovations at St. Pauls Church in Nantucket, Ma
Before and after repairs on riven lath at the Emily Dickinson Museum in Amherst, MA