There are 10 circular kilns onsite. Each one was heated up to 1200 to 1371 Degrees Celsius (2300 to 2500 Fahrenheit). This process took 6-10 days and was until the 1960's when they switched to natural gas, the Fireman had to heat the kilns by shovelling coal. I can only image what a hot and gruelling job that must have been.