Care and Preservation of Stone Sculptures

Subrata Sen

Stone sculptures, indoor and outdoor sculptures, can be found everywhere around us. These could be temple deities, family worship idols, miniatures in marble, lions and birds standing on gate pillars and stone carved outdoor exhibits that find way in our gardens and balconies. Stones such as soapstone, alabaster, sandstone, limestone, marble, basalt and granite have been used in sculptures. Stone sculptures can boast of best longevity and easy-care options amongst all heritage objects and this could involve simple cleaning. However, as any material, stones also undergo natural weathering and deterioration with time. Stability induced by good house-keeping practices, proper display and storage can be key to ensure that they are passed on to future generations in pristine conditions. Caring for sculptures is easy once we know the material, the signs of deterioration and ways of preventive care.

What are Sculptures?

What is the history / origin of stone sculptures?

What stones are used in sculptures?

How to identify stones used in stone sculptures?

What can go wrong with a stone sculpture and why?

Why are there cracks in my stone sculpture?

What can I do to prevent cracks in stone sculptures?

Should I clean stone sculpture at home?

Should I apply protective coatings on sculptures?

What is the best way to move sculptures?

What are the best ideas for displaying my sculpture?

How do I store my sculpture?

How do I look after my outdoor stone sculpture?

What are Sculptures? What is the history / origin of stone sculptures?

Sculptures are three dimensional objects made of stone that may be carved out or assembled by joining more than one piece. Stone being a durable material, several stone sculptures have survived over the years in various parts of the world.

Petroglyphs or rock engraving on cave walls were perhaps the earliest form of carvings in stone. The Löwenmensch figurine and the Venus of Hohle Fels in Germany, are considered the oldest statues in the world. The oldest known life-sized statue is Urfa Man found in Turkey.

What stones are used in sculptures?

The combination of the natural colour, grain, texture of the stone and the man-made carving creates the unique stone sculpture art. A range of stones with varied textures have been used with great advantage for carving sculptures.

Common stones used are soapstone, alabaster, red sandstone, limestone, white marble, basalt and black granite. Many other stones have also been used depending on geography, availability and cost. The selection of stone for sculpture is based on softness/hardness, availability and the colour, texture or finish.

How to identify stones used in stone sculptures?

The main classification of stone in nature is based on its origin/formation and according to this there are three main types of stones- igneous, sedimentary and metamorphic.

• Igneous stones are tough, cooled lava melts with little texture or layering. Rocks like these contain mostly black, white and/or gray minerals. These include granite, diorite, basalt, and obsidian. These are some of the hardest stones used for sculpture.

• Sedimentary stones such as limestone, sandstone or shale are hardened sediments carried in rivers and deposited in lakes and oceans. With time, the sediments lose water and become cemented under temperature and pressure to form rock with a distinct layer (strata) or beddings. They are usually brown to grey in colour and may have fossils and water or wind marks. Many varieties of sandstone and limestone, which vary greatly in quality and suitability for carving, are used for sculpture.

• Metamorphic stones are formed when a sedimentary rock or igneous rock is exposed to heat and pressure and undergoes a chemical change which forms a new crystalline material. The most well-known metamorphic rocks used in sculpture are the marbles, which are recrystallized limestones.

The colours and textures of stone can also be useful properties for identifying stones. As complex mineral forms, stones are also richly variegated in colour by the irregular veining that runs through them.

• Marble stones are fine-grained with colours ranging from pristine white to blue/grey, pink and black and can be carved with delicate detail and finished with a high polish. Marble also has a translucent quality, that is the stone seems to glow as it responds to light.

• The granites may be predominantly black or white or a variation of greys, pinks, and reds. They do not have uniform colouring, but a more salt-and-pepper quality and it may glint because of mica and quartz crystals in it.

• Sandstones vary in texture and are often more warm- coloured in a range of buffs, pinks, yellows and reds.

• Limestones, although whitish, may vary greatly in colour, and the presence of fossils may add a different texture to their surfaces.