Rotten stone, sometimes spelled as rottenstone, also known as tripoli, is fine powdered porous
rock
Rock most often refers to:
* Rock (geology), a naturally occurring solid aggregate of minerals or mineraloids
* Rock music, a genre of popular music
Rock or Rocks may also refer to:
Places United Kingdom
* Rock, Caerphilly, a location in Wales ...
used as a
polishing abrasive
An abrasive is a material, often a mineral, that is used to shape or finish a workpiece through rubbing which leads to part of the workpiece being worn away by friction. While finishing a material often means polishing it to gain a smooth, reflec ...
for metalsmithing and in
woodworking
Woodworking is the skill of making items from wood, and includes cabinet making (cabinetry and furniture), wood carving, joinery, carpentry, and woodturning.
History
Along with stone, clay and animal parts, wood was one of the first mate ...
. It is usually weathered
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 whe ...
mixed with
diatomaceous, amorphous, or crystalline
silica
Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , most commonly found in nature as quartz and in various living organisms. In many parts of the world, silica is the major constituent of sand. Silica is ...
. It has similar applications to
pumice
Pumice (), called pumicite in its powdered or dust form, is a volcanic rock that consists of highly vesicular rough-textured volcanic glass, which may or may not contain crystals. It is typically light-colored. Scoria is another vesicular v ...
, but it is generally sold as a finer powder and used for a more glossy polish after an initial treatment with coarser pumice powder. Tripoli particles are rounded rather than sharp, making it a milder abrasive.
It is usually mixed with oil, sometimes water, and rubbed on the surface of
varnished or lacquered wood with a felt pad or cloth. Rotten stone is sometimes used to buff stains out of wood. Some polishing
wax
Waxes are a diverse class of organic compounds that are lipophilic, malleable solids near ambient temperatures. They include higher alkanes and lipids, typically with melting points above about 40 °C (104 °F), melting to giv ...
es contain powdered rotten stone in a paste substrate. For larger polishing jobs, rotten stone mixed with a binder is applied to polishing wheels.
It has also been used to polish
brass
Brass is an alloy of copper (Cu) and zinc (Zn), in proportions which can be varied to achieve different mechanical, electrical, and chemical properties. It is a substitutional alloy: atoms of the two constituents may replace each other wit ...
, such as that found on military uniforms, as well as steel and other metals. Plates used in
daguerreotypes were polished using rotten stone, the finest abrasive available at the time.
It is also used to polish jewelry and in toothpastes. Its more common use is as a filler, as used in plastics, paint and rubber.
Sources
Rottenstone has been extensively worked in
South Wales along the outcrop of the
Carboniferous Limestone
Carboniferous Limestone is a collective term for the succession of limestones occurring widely throughout Great Britain and Ireland that were deposited during the Dinantian epoch (geology), Epoch of the Carboniferous period (geology), Period. T ...
, particularly within the
Brecon Beacons National Park
The Brecon Beacons National Park ( cy, Parc Cenedlaethol Bannau Brycheiniog) is one of three national parks in Wales, and is centred on the Brecon Beacons range of hills in southern Wales. It includes the Black Mountain ( cy, Y Mynydd Du) i ...
. It occurs at the top of the sequence where the
Upper Limestone Shales have been weathered. Innumerable workings were initiated and later abandoned during the course of the nineteenth century, leaving a characteristic terrain of humps and hollows. A notable example is that on the flanks of
Cribarth
Cribarth, sometimes referred to as the Sleeping Giant, is a hill in the Brecon Beacons National Park located in the traditional county of Brecknockshire (currently administered part of the unitary authority of Powys) in southern Wales. The summit ...
exploited by industrial entrepreneur
John Christie.
[Hughes, S. 1990 ''The Archaeology of an Early Railway System: The Brecon Forest Tramroads'' RCAHMW, Aberystwyth, Dyfed ]
In the United States it is mainly produced in Arkansas, Illinois, and Oklahoma.
See also
*
Metal polishing
Polishing and buffing are finishing processes for smoothing a workpiece's surface using an abrasive and a work wheel or a leather strop. Technically, ''polishing'' refers to processes that uses an abrasive that is glued to the work wheel, whil ...
*
Pumice
Pumice (), called pumicite in its powdered or dust form, is a volcanic rock that consists of highly vesicular rough-textured volcanic glass, which may or may not contain crystals. It is typically light-colored. Scoria is another vesicular v ...
*
Wood finishing
Wood finishing refers to the process of refining or protecting a wooden surface, especially in the production of furniture where typically it represents between 5 and 30% of manufacturing costs.
Finishing is the final step of the manufacturing ...
References
External links
''On Rotten-Stone and Emery''. Penny Magazine of the Society for the Diffusion of Useful Knowledge. July 15, 1843 Volume 12, p. 270
Abrasives
Metalworking
Industrial minerals
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