7.    In-situ modelled decorations in plaster on facades

In-situ hand modelling of plaster decorations on facades is a very old crafts technique belonging to the stucco workers profession. 

Typical hand modelled elements can be consoles, festoons, medallions, animal heads, column capitals, etc. See examples on drawing 1 and 21.

First a full scale drawing of the decoration, either produced by the craftsman, an artist or the architect, is made on paper, which is impregnated with a coat of shell lacquer. This is however not always necessary, if the paper is sufficiently strong and stiff. Now the outline of the figure is riddled with an awl, making small holes through the paper, now called a ponse.

With a little slightly un-tight linen bag, filled with charcoal-dust, the black powder is sprinkled over the ponse and through the pricked holes in the paper. This of cause is done at the exact place for the decoration at the facade, and when the ponse is removed, the contours of the decoration is nicely transferred to the surface.

The outlines are drawn up and the application of mortar prepared by cutting grooves in the surface and the contour with a chisel. After the usual pre-watering of the ground, the mortar, preferably a medium fine hydraulic lime mortar (1:2:9), is thrown on. Now first the exact outline and next the details of the decoration are hand modelled with the use of stucco workerís tools: various round, square and hollow spatulas.

If the construction is thicker than 5 - 6 cm it is recommended to use two separate layers of mortar, as previously described. The binding to the ground will also in that case have to be reinforced with laths in stainless steel. 

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