Rethink Heritage

Some materials need surface protection and some have to be painted for a better appearance. Protection is needed against weather conditions, mostly against humidity, sun and heat. Humidity destroys materials, the sun can damage surfaces with its ultraviolet rays, and differences of warmth and chill ruin substances. 

Painting is a very thin layer of material, resistant to some external influences. This protection has a limited lifespan and has to be repeated in time. Only modern painting materials are without pigment and can be transparent. Pigments are originally special earths, added to liquid. Those are mostly brown colours, reddish can be achieved by cow’s blood. 

On the Pannonian Plain can be seen a grey strip at the bottom of the whitewashed walls: the grey colour discourages chickens from collecting lime for hardening the eggs. Those buildings have walls open to the yard whitewashed really in white, the rear walls are dark, brown or red. The blue colour in the lime coating is a result of copper sprinkling of the vineyards against insects and other diseases.  

Partly painted walls are only decorative: lime whitewashing in Arab countries around the windows is done for hygienic reasons – against insects - crosses and roses in the window corners in wood architecture of Slovakia is pure decoration, showing the importance of these elements.

Plaster is a building material, as a surface finish for coating and protecting inner and outer walls. Plaster is a thick layer of gypsum, lime or cement, mixed with water and sand, placed on the wall surface. This protection is stronger than painting, the problem is its thickness, which can peel off in time.

Plaster has to cling firmly and this is the most important problem: the drying of both wall material and plaster can split them and the plaster can fall apart. Smooth walls are not suitable for this, its surface has to be rough, with a lot of small or bigger elements, on which plaster can cling. The simplest aspect is chopping the wood. The surface of stone or brick walls are composed of bricks and connecting mortar and is suitable for good binding. 

Clay plaster is the oldest, and also the most sustainable alternative to modern plasters, with a lower embodied energy than other plasters with their binding materials. Clay plaster needs to be reinforced, which increases its strength, it breathes and doesn't need to be painted.

Gypsum plaster has a very short time for its solidification: this has both advantages and drawbacks – the short time for its finishing provides essential problems in work. On the other hand, gypsum plaster is very hard and can also be used as bearing material between wooden beams.

Lime plaster is the most usable plaster, as a composite of calcium hydroxide and sand, mixed with water. The final effect is achieved with the transformation of calcium dioxide into calcium carbonate (limestone). It is more flexible than gypsum and breathes better than cement plasters, but is not as sustainable as clay plaster.

Plaster is normally whitewashed with a lime covering, renewed at least every year.

The interior plastering covers the wall's construction and provides a good base for colouring. Lime plaster can be covered by lime colours: the use of material with the same base is important. While the plaster is rough levelling of wall elements, painting is its fine coating.

The walls in more pretentious architecture can be fitted with decorative details such as fresco, sgraffito and stucco techniques.

Fresco is a method of painting water-based pigments onto freshly applied plaster. The colours are made by grinding dry powder pigments in water, and they dry and set with the plaster, becoming a permanent part of the wall. Those paintings are durable to weather conditions and can also be found on the outer walls of some churches. 

Sgraffito is an art of painting, made by cutting the coloured surface into plaster. The plaster is tinted by the aggregate and the surface by the chosen colour, the incisions show the plaster's colour, scratches reveal parts of the underlying layers. This decoration is limited to lines mostly, but it is very useful on surfaces for highlighting building elements of the construction, bricks, columns, cornices etc.

Stucco is the most used element in baroque architecture, in which the elements are added to the wall surface, made of aggregates, a binder and water. A gypsum binder is mostly used because of its hardness and short time of hardening. Gypsum is produced by heating the rough material to around 150 degrees centigrade. When mixed with water, the dry plaster powder reforms into 'gypsum', which starts to set about ten minutes after mixing; the final hardness is achieved after three days. Stucco can be used as corner laths or line decoration on walls and ceilings. This is a three dimensional decoration, the laths can be shaped in several profiles with simple moulds.

Stucco was the most important sculptural decoration in baroque architecture, placed not only on walls and edges, but also on the spherical surfaces of domes and arches.