A temper is a non-plastic material added to clay to prevent shrinkage and cracking during drying and firing of vessels made from the clay.
Tempers may include:
*Bone;
*
Chaff
Chaff (; ) is the dry, scaly protective casing of the seeds of cereal grains or similar fine, dry, scaly plant material (such as scaly parts of flowers or finely chopped straw). Chaff is indigestible by humans, but livestock can eat it. In agri ...
;
[
*Charcoal;
*Ground ]schist
Schist ( ) is a medium-grained metamorphic rock showing pronounced schistosity. This means that the rock is composed of mineral grains easily seen with a low-power hand lens, oriented in such a way that the rock is easily split into thin flakes ...
;
*Wood ash
Wood ash is the powdery residue remaining after the combustion of wood, such as burning wood in a fireplace, bonfire, or an industrial power plant. It is largely composed of calcium compounds along with other non-combustible trace elements presen ...
;[
*Sand or crushed ]sandstone
Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks.
Most sandstone is composed of quartz or feldspar (both silicat ...
;limestone
Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms w ...
;
*Crushed igneous rock
Igneous rock (derived from the Latin word ''ignis'' meaning fire), or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rock is formed through the cooling and solidification of magma o ...
s, such as volcanic rock
Volcanic rock (often shortened to volcanics in scientific contexts) is a rock formed from lava erupted from a volcano. In other words, it differs from other igneous rock by being of volcanic origin. Like all rock types, the concept of volcanic ...
, feldspar
Feldspars are a group of rock-forming aluminium tectosilicate minerals, also containing other cations such as sodium, calcium, potassium, or barium. The most common members of the feldspar group are the ''plagioclase'' (sodium-calcium) felds ...
, or mica
Micas ( ) are a group of silicate minerals whose outstanding physical characteristic is that individual mica crystals can easily be split into extremely thin elastic plates. This characteristic is described as perfect basal cleavage. Mica is ...
;[
*]Grog
Grog is a term used for a variety of alcoholic beverages.
The word originally referred to rum diluted with water (and later on long sea voyages, also added the juice of limes or lemons), which British Vice-Admiral Edward Vernon introduced ...
;Plant fiber
Fiber crops are field crops grown for their fibers, which are traditionally used to make paper, cloth, or rope.
Fiber crops are characterized by having a large concentration of cellulose, which is what gives them their strength. The fibers may b ...
;
* Horse manure (dried and sifted);
*Crushed mollusc shells (including fossil
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...
ized)[ (see Shell tempering in the Mississippian culture); and
*Freshwater sponge spicules.]pottery
Pottery is the process and the products of forming vessels and other objects with clay and other ceramic materials, which are fired at high temperatures to give them a hard and durable form. Major types include earthenware, stoneware and ...
do not require the addition of tempers. Pure kaolin clay does not require tempering.[
]
See also
Ceramic#Archaeology
Citations
References
*
*
*
* {{cite journal, format=PDF, last1=Weinstein, first1=Richard A., last2=Dumas, first2=Ashley A., title=The Spread of Shell-Tempered Ceramics along the Northern Coast of the Gulf of Mexico, journal=Southeastern Archaeology, publisher=Maney Publishing, volume=27, issue=2, pages=202–221, date=2008, url=http://www.coastalenv.com/sarc-27-02-202-221-e.pdf, accessdate=5 November 2011, url-status=dead, archive-url=https://web.archive.org/web/20120425141409/http://www.coastalenv.com/sarc-27-02-202-221-e.pdf, archive-date=25 April 2012
External links
Common Inclusions and/or Tempers
- Images (including micrographs) of shards with various tempers.
Ceramic materials