Lime plaster is type of plaster

Plaster

Plaster is a building material used for coating walls and ceilings. Plaster starts as a dry powder similar to mortar or cement and like those materials it is mixed with water to form a paste which liberates heat and then hardens. Unlike mortar and cement, plaster remains quite soft after setting,...

 composed of hydrated lime, sand and water. Lime plaster is similar to Lime mortar

Lime mortar

Lime mortar is a type of mortar composed of lime and an aggregate such as sand, mixed with water. It is one of the oldest known types of mortar, dating back to the 4th century BC and widely used in Ancient Rome and Greece, when it largely replaced the clay and gypsum mortars common to Ancient...

, the main difference is the based on use rather than composition. Traditional lime plaster contains also horse hair to reinforce plaster.

It is sold as 'bagged' powder or hydrated lime; or is available as lime putty. Lime putty generally being considered more suitable for pure lime application.

Non-hydraulic lime is the most commonly used and known lime, also called (high) calcium lime or air lime, as it sets only by reaction with in the air and will not set until dry. This causes limitations in construction use as the lime can remain soft for months or years. Non-hydraulic lime can only set through carbonation (re-absorption of CO₂).

Hydraulic lime

Hydraulic lime

Hydraulic lime is a variety of lime, a slaked lime used to make lime mortar. Hydraulicity is the ability of lime to set under water. Hydraulic lime is produced by heating calcining limestone that contains clay and other impurities. Calcium reacts in the kiln with the clay minerals to produce...

 and hydrated lime must not be confused. Hydrated lime is merely a form in which lime can be supplied (as opposed to quicklime or lime putty); while 'hydraulic' refers to a water resistancy characteristic of the lime.

Safety issues

Lime is an extremely caustic material when wet, with a pH of 12. (Lime becomes pH neutral when carbonated). As such, the use of protective goggles, gloves, and clothing are necessary when working with lime. Clean water should also be kept readily accessible for first aid purposes when working with lime in case of accidental eye or skin exposure.

• First aid for cases of skin exposure to lime involves neutralization with very mild acid such as vinegar or lemon juice.
• First aid for cases of accidental eye exposure consists of repeatedly flushing the eye for several minutes with fresh water. Medical attention should be sought in such cases.

Historical use in the arts

One of the earliest examples of lime plaster dates back to the end of the eighth millennium BC. Three statues were discovered in a buried pit at 'Ain Ghazal

'Ain Ghazal

Ain Ghazal is a Neolithic site located in North-Western Jordan, on the outskirts of Amman. It dates as far back as 7250 BC, and was inhabited until 5000 BC...

 in Jordan that were sculpted with lime plaster over armatures of reeds and twine. They were made in the pre-pottery neolithic

Pre-Pottery Neolithic B

Pre-Pottery Neolithic B is a division of the Neolithic developed by Dame Kathleen Kenyon during her archaeological excavations at Jericho in the southern Levant region....

 period, around 7200 BC. The fact that these sculptures have lasted so long is a testament to the durability of lime plaster.

Historical uses in Building

• Some of the earliest known examples of lime use for building purposes are in early Egyptian buildings (primarily monuments). Some of these examples in the chambers of the pyramids, which date back to around 2000 B.C., are still hard and intact.
• Archaeological digs carried out on the island of Malta have shown that in places like Tarxien
  Tarxien Temples
  The Tarxien Temples are an archaeological complex in Tarxien, Malta. They date back to approximately 2800 BC. The site was accepted as a UNESCO World Heritage Site in 1980 along with the other Megalithic temples on the island of Malta.-Description:...
  
   and Hagar, lime stucco was also used as a binder to hold stone together and as well as for decoration at sites dating back as far as 3000-2500 B.C.
• At el-Amarna
  Amarna
  Amarna is an extensive Egyptian archaeological site that represents the remains of the capital city newly–established and built by the Pharaoh Akhenaten of the late Eighteenth Dynasty , and abandoned shortly afterwards...
  
  , a large pavement on brick was discovered that dates back to 1400 B.C. It was apparently the floor of part of the harem of King Amenhotep IV
  Akhenaten
  Akhenaten also spelled Echnaton,Ikhnaton,and Khuenaten;meaning "living spirit of Aten") known before the fifth year of his reign as Amenhotep IV , was a Pharaoh of the Eighteenth dynasty of Egypt who ruled for 17 years and died perhaps in 1336 BC or 1334 BC...
  
  .
• Ancient Chinese used Suk-wui (the Chinese word for slaked lime) in the construction of The Great Wall of China.
• The Aztec Empire and other Mesoamerican civilizations used lime plaster to pave streets in their cities. It was also used to coat the walls and floors of buildings.

See also

Further reading

Cedar Rose Guelberth and Dan Chiras, The Natural Plaster Book: earth, lime and gypsum plasters for natural homes'

J.N. Tubb, Canaanites, London, The British Museum Press, 1998

Stafford Holmes, Michael Wingate, Building With Lime: A Practical Introduction, Intermediate Technology Publications Ltd,

External links

• General Guidelines for Working with Lime Mortar and Limewash, Ellen Hagsten,Traditional & Sustainable Building, March 2007
• British Museum: Lime Plaster Statues
• Yuval Goren, Paul Goldberg, Peter W. Stahl and Udo H. Brinker Journal of Field Archaeology, Vol. 18, No. 1 (Spring, 1991), pp. 131–140, Published by: Boston University