Venetian Plaster and its practical definitions

Practical definitions

While talking about Venetian stuccowork we often meet some not so common words; let's see some of them together:

 
Fresco: fresh plaster just spread coloring technique.

Lime paste: calcium hydroxide. It comes from lime-stone, sugar limestone mostly made by calcite with a 96% of its content by calcium carbonate, while remaining 4% by other minerals (quartz, chlorite, garnets, etc). Lime stone is properly cooked, then 'slaked' covering it with water in specific 'tubs'. Its role in the plaster is the binder.

Quicklime: Calcium oxide. It is the result of calcium carbonate, under heat, after releasing carbon dioxide.

Carbonatation: physical-chemical process through which water released from plaster during hardening and drying, allows a reaction between slaked lime and carbon dioxide in the air that will cover calcium carbonate.

Trowel: flat-bladed hand tool, a small hand tool with a short handle and a flat, usually painted blade used for spreading, shaping and smoothing plaster, cement or mortar.

American Trowel: a steel rectangular hand tool, fit for faux finishing.

Wax: it is an ester composed by univalent alcohol and carboxylic acids. It can be either animal or vegetable or mineral. The first is produced by bees, the second is secreted by certain plants, the third comes from petroleum distillation.

Crushed pottery: Powder that comes from crushing different latentious (for ex. tiles, bricks) cooked clay products. Its role in the mixture is to aggregate components.

Encaustic: having wax colors fused to a surface by heat.

Float: rectangular hand tool, fit for spreading and beating plaster.

Polishing: smoothing with shine or faux finishing trowel, after paint spreading water and neutral soab.

Dry polishing: second polishing of dried and hardened faux finishing obtained paint spreading bee wax and turpentine followed by wool cloth rubbing.

Highlighting: light painting effect obtained by glazing with light pigments.

Faux finishing: (stucco prepared with white marble powder and slaked lime). Nowadays with faux finishing we mean a finishing plaster basically made by stonelime and marble or stone powder. It is so called (faux finishing or marmorino) because it is the best marble representation both in composition and in final look.

White natural faux finishing: marmorino without any kind of pigments.

Faux finishing for decoration: it's either colored or not marmorino, made by limestone and very tiny marble powder (Kaolin); it is very malleable.

Shading: light and shade painting effect, obtained by glazing with properly balanced dark pigments.

Istrian Stone: calcareous stone coming from Istrian headlands and cliffs.

Pigmentation: mixing base faux finishing with properly wet and sifted pigment.

Pozzolan: red or brown tuffaceous rock with high silicon content. Great plaster aggregator because with lime it makes hydraulic cement.

Refinement: a specific name to define the third faux finishing, or any other relief decoration, layer. It is a mixture where aggregate is in lower proportion than binder.

Rendering: operation to form render.

Render: it is a quite fluid mortar just one coat which is thrown with trowel over bricks or other base so that it fills any interstice. It makes a very rough first coat, fit for next coats.

Decoration stucco: mixture of limestone and marble powder, very tiny, used for shaping.

Strong plaster: mixture of limestone and marble pwder with cooked gypsum added and eventually gypsum setting retarding element. Mainly used in high relief shaping.

Turpentine: essential oil from conifers resin distillation.

Glazing: very liquid color paint spreading over very fresh faux finishing, in several coats, crossing one another.