The firing shrinkage of a clay is usually about the same as the drying shrinkage. Total shrinkage will usually be about 8-12%. The next stage that happens during the firing process is vitrification. This is the hardening, tightening and finally the partial glassification of the clay. Vitrification results from fusions or melting of the various components of the clay.
Middlesboro is served by the Middlesboro-Bell County Airport, which is a single runway, general aviation airport and is the second oldest airport still in use in Kentucky, ranking behind Bowman Field in Louisville.. The airport was established in 1944, however, the first recorded flight into the city was in 1912.
Hazard is a city in Perry County, Kentucky, United States. The population was 4,806 at the 2000 census. It is the county seat of Perry County. A post office named Perry Court House was established in the area in the 1820s, though some reports note that locals had always referred to the area as Hazard. The town's name was officially changed to Hazard in 1854.