Pottery Capital of America
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This is a multistage Earth cache. Meaning that you will have to visit two locations, close in proximity to one another, in order to complete the cache. Second location is just a sort distance from the first. Just down the street before the highway on ramp. Parking next to the kiln.
Location #1- 2 Historic Information Markers
Given coordinates.
Location #2- Kiln
N 40 36.985
W 080 34.873
The City of East Liverpool was once the Pottery Capital of America. The topography of the area is hilly and rugged, and is dissected by many streams created by glacial runoff. The action of these streams has created a contour marked by narrow ridges alternating with steep valleys. The rocks formed by this geological activity consist of shales, limstones, and sandstone, interspersed with layers of coal and clay. The coal formation clays of the area are derived from clay sediments purified during the coal age. The most important of these clays are of the Lower Kittanning variety, with a low iron content and greater plasticity. Veins of the buff-burning clay range from eight to thirty feet in thickness.
Clay is a naturally occurring material composed primarily of fine-grained minerals. Clay deposits are mostly composed of clay minerals, a subtype of phyllosilicate minerals, which impart plasticity and harden when fired or dried. They also may contain variable amounts of water trapped in the mineral structure by polar attraction. Organic materials which do not impart plasticity may also be a part of clay deposits.
Clay minerals are typically formed over long periods of time by the gradual chemical weathering of rocks, usually silicate-bearing, by low concentrations of carbonic acid and other diluted solvents. These solvents, usually acidic, migrate through the weathering rock after leaching through upper weathered layers. In addition to the weathering process, some clay minerals are formed by hydrothermal activity. Clay deposits may be formed in place as residual deposits in soil, but thick deposits usually are formed as the result of a secondary sedimentary deposition process after they have been eroded and transported from their original location of formation.
Read for Location #2- Kiln
The most visible outer part, which is bottle shaped is known as the HOVEL and can be a variety of shapes and sizes; it can be up to seventy feet tall. The HOVEL acts as a chimney; taking away the smoke, creating air flow and protecting the oven inside from the weather and uneven draughts. The inner part is the kiln proper. It is a round structure with a domed roof, the CROWN. Iron bands known as BONTS, set about twelve inches apart, run right round the circular oven to strengthen it as it expands and contracts during the firing.
On average, the bottle ovens were fired once a week. A BISCUIT (first) firing took three days and a GLOST (second) firing took two days. It required about fifteen tons of coal to fire one bottle oven once, and almost half the heat generated would go up the bottle shaped chimney as smoke.
After placing the CLAMMINS or door, the entrance to the kiln was blocked up with bricks and sand and the kiln was then ready to fire. Fires were lit in the FIREMOUTHS and BATTED, that is, coal was loaded onto the fires at intervals of about four hours. In the early stages of firing the temperature was kept low while the moisture in the ware was driven out. This was known as SMOKING.
After about 48 hours, the maximum temperature between 1832 F and 2282 F was achieved and this was maintained for approximately two to three hours.
The fires were then left to go out. Fine control of the draught was achieved by altering the position of the DAMPERS in the CROWN.
Dampers are flaps made from iron and firebrick, which the fireman could operate from ground level by means of a pulley system. By opening selected DAMPERS, the draught in different sections of the kiln could be increased, thus causing the fires to burn more fiercely and raising the temperature. By closing the DAMPERS the temperature could be kept steady or lowered.
When the firing was over, the CLAMMINS was broken down and the kiln left to cool. As soon as it was sufficiently cool for a man to enter without being harmed by the heat, the kiln was emptied or drawn.
Ware was fired in ceramic boxes called Saggars. A SAGGAR is a fireclay container, usually oval or round, used to protect pottery from marking by flames and smoke during firing in a bottle kiln. Placing pottery in saggars required special knowledge. Plates were reared or dottled, which means that they were carefully separated from each other by thimbles to prevent the glaze from making them fuse together in the glost firing.T he finished saggar was fired in the kiln and lasted for thirty to forty firings if they were not broken.
How ceramics mature in a kiln is effected by the peak temperature, the duration in which it’s fired, and the amount of oxygen in the kiln. Oxidizing atmospheres will cause the oxidation of clay. A reducing atmosphere will strip oxygen off the surface. Glazes rich in Iron with turn brown in oxidizing atmosphere, were they will turn green in a reducing atmosphere. This explains the reason that much of our town’s early pottery is brown and other dark shades.
In order to complete this earthcache You must answer the following questions
Location #1- 2 historic markers
1. Who established the pottery industry in east Liverpool and were was he born
2. What 2 resources made the pottery industry possible.
3. What 2 things were responsible for the decline in the pottery industry.
Location #2-Kiln
1. What shape does the kiln exibit. What was the reason for this shape.
2. Estimate the height of the kiln and the width inside the kiln.
3. The kiln is located behind the headquarters for what organization.
Referances:
The City of Hills and Kilns by William C. Gates
Wikipedia
Pottery-Magic
Additional Hints
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