Venetian Plaster - Polished Stucco

This is slow, careful handwork. Each coat is very thin, and the result depends mainly on timing. A decorator usually works in this order:

Preparing the wall

The wall has to be flat, sound, dry and clean. Holes and cracks are filled, and any loose or flaking old paint comes off. Then the decorator applies a suitable primer so that the whole surface absorbs evenly. A glossy finish shows up every bump and dip, so preparation often takes longer than the plaster itself.

Base coat

The first coat goes on thinly with a stainless steel trowel and evens out small imperfections. It dries according to the manufacturer's instructions, usually for a few hours. Any thicker spots are then lightly sanded.

Patterned coats

The second and later coats go on in short strokes in different directions, which creates the typical marble-like pattern. Two to four thin coats are common. The decorator then compresses and burnishes the final coat at exactly the right moment, when it is no longer wet but not yet fully hard. That is when the sheen starts to appear.

Waxing and polishing

Once the plaster is dry, a thin layer of wax goes on and is buffed with a cloth or the trowel. The wax deepens the colour, adds shine and protects the surface from water and dirt.

• Lime-based Venetian plaster is the traditional option, made with marble powder. It lets moisture vapour pass through, and because it is alkaline it resists mould better. It suits living spaces well
• Synthetic resin-based plaster is easier to work with and is often more resistant to scuffing. It usually breathes less
• Waxes come in natural and synthetic versions, some with a pearl or metallic effect. A thick layer of wax makes the wall less breathable, so it goes on thinly
• Colour can be white, ready-tinted or mixed to match a sample. Light and mid tones hide small flaws better, while dark and metallic shades show every stroke

The tools are stainless steel trowels, smaller spatulas for corners, fine sandpaper and clean cloths. The trowel must be free of scratches, otherwise it will transfer them onto the wall.

A few factors decide how demanding the job is, and so how much it costs:

• The condition of the wall, because an uneven or damaged wall needs more filling and sanding
• The number of coats and how high a gloss you want
• Special effects such as pearl, metallic pigments or several colours on one wall
• Lots of corners, window reveals, sockets and switches, which slow the work down
• Room height and access, for example above a staircase or behind built-in furniture
• Whether the room is cleared and whether other trades are working there at the same time, since dust on a fresh coat causes problems

Venetian plaster suits living rooms, bedrooms, hallways, landings and offices. Once waxed, it can also go in a kitchen away from the worktop and in a bathroom away from direct splashing. A common story: someone orders it for a shower enclosure instead of tiles, and is then surprised when the constantly wet surface starts to change. Areas like that need different systems, such as purpose-made waterproof finishes. Ask your contractor about these before you decide.

Inside your own home you normally do not need any permission, because this is purely a surface finish. If you live in a flat and want to change walls in shared areas such as the stairwell, agree it first with the building management or the owners' association.

• Poor preparation, so the plaster peels off dusty or greasy patches and the polish shows up every unevenness
• Coats that are too thick, which dry slowly and can crack
• Uneven strokes that leave patches, stripes and blotches
• Burnishing at the wrong moment: on a wet coat the plaster drags, on a dry one the sheen will not develop
• Wax applied thickly or unevenly, which looks blotchy and artificial
• Working in a draught or in direct sunlight, so the plaster dries too fast to polish

Mistakes that would disappear under ordinary paint are obvious here straight away. Often the only fix is to remove the whole top layer.

Polished plaster is safe work, but it takes practice. If you want to try it yourself, start on a board or on a small wall that is not the focal point of the room. Follow the technical data sheet for the plaster you are using.

1. Clear the room, cover the floor and mask the surrounding areas with tape.
2. Check the wall with a long straightedge, then fill and sand any unevenness.
3. Dust the surface and apply the primer recommended by the plaster manufacturer.
4. Spread a thin base coat and let it dry.
5. Apply further thin coats in short, criss-cross strokes, always waiting for the previous coat to dry.
6. Compress and burnish the final coat with a clean trowel once it is no longer wet but not yet hard.
7. When everything is fully dry, apply a thin layer of wax and buff it with a cloth.
8. Wash and dry the trowels immediately so no residue hardens on them.

If your sample does not turn out as you hoped, that is normal. For a feature wall that really matters, call in an experienced decorator.

• Look at the wall against the window light and under the low, angled light of a lamp to spot waves or obvious unevenness
• The pattern should look even across the whole wall, with no hard edges between sections
• The sheen should be uniform, with no dull patches or wax smears
• There should be no cracks, bubbles or peeling spots
• Corners, edges and the areas around sockets should be neatly finished
• Ask for the names of the plaster and wax used and for care instructions