Rappausta

Rappausta is the Finnish term for plastering, the technique of applying plaster to interior and exterior walls and ceilings to create a finished surface. The plaster layer provides a protective coating, helps control moisture, and offers a base for paint or other treatments. It can be applied to a variety of substrates, including brick, concrete, stone, wood lath, or gypsum boards, and is used in both traditional and modern construction.

Materials used in rappausta vary by need and climate. Lime-based plasters have long been valued for their breathability and compatibility with historic buildings, while cement-lime blends and gypsum-based plasters are common in contemporary work for quicker set and greater strength. Exterior renders (often cement or lime-cement mixes) protect masonry from weather, while interior plasters produce a smooth or textured finish. Finishes range from highly smooth to decorative textures, with several coats typically involved in traditional plastering.

The application process typically begins with substrate preparation, including cleaning and dampening to improve adhesion. Plaster is mixed to achieve the correct consistency and then applied in coats. A base coat, or scratch coat, is spread to establish keying; after it stiffens, a second coat, the brown coat, is applied for thickness and levelness; a final finish coat provides the desired smoothness or texture. Tools such as a plastering trowel, hawk, and scratch comb are commonly used, and proper curing conditions are important to prevent cracks.

Rappausta influences both the appearance and the durability of a surface. Cracks or delamination can indicate movement, moisture intrusion, or substrate problems and may require remediation, which can involve re-plastering or applying a new finish. In many regions, rappausta remains an essential method for restoring historic walls and for achieving durable, breathable surfaces in new construction.