What is stucco lustro?
Stucco lustro (“lustrous stucco”) is a historic Italian plastering technique in which thin coats of slaked lime mixed with marble dust or marble sand are built up and burnished to a sheen, often to imitate marble. The top coat is pigmented and treated with soap (traditionally Venetian soap), and later waxed. Historically the surface was compacted with a heated iron or hot trowel, which gives a silky gloss and a sense of depth. The genuine technique is labour-intensive and only a few specialists still master it.
How it differs
- Venetian plaster and marmorino: related polished lime plasters from the same tradition. Suppliers often use the names interchangeably.
- Gypsum-based imitation marble: much modern “stucco lustro” is a cheaper copy in gypsum-bound material. It looks similar but is not the same thing.
- Scagliola: something different, namely gypsum with animal glue and pigment, used to imitate marble or inlaid stone.
Application
- Provide a sound mineral background. Traditionally this is a lime plaster. On other backgrounds, follow the manufacturer’s system, including the correct base coat.
- Build up in thin coats. Several coats of lime and marble dust, wet on wet, from coarse to fine. The last coat is very fine and coloured.
- Burnish at the right moment. Trowel while the coat is still slightly damp, with pressure and a smooth trowel. Too wet leaves smears, too dry gives no sheen.
- Get the heat right. If you work with a hot iron or trowel, too hot is as bad as too cold.
- Protect the surface. Once dry, rub in soap or wax and buff it, which makes it less prone to staining.
- Try a sample board first, especially for colour and sheen.
Common mistake: applying coats too thick or letting them dry too far before the next. They then bond poorly and the sheen is uneven.
Related terms
- Scagliola
- Lime putty
- Marble
- Decorative plaster
- Pigment
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