Vacuum formed shapes are manufactured from high purity alumina silica fibers in a onepiece design that eliminates metal leakage. These ceramic fibers are formed together with a special bonding process to create a smooth, homogeneous, finished surface that is resistant to thermal shock. They also have a low thermal conductivity that requires no pre-heating and they are reusable, with proper treatment, for multiple casting campaigns. These insulating, lightweight shapes are custom formed to customer specifications for ease of installation and maximum performance at the lowest total cost. Good casting practices dictate keeping these products in a dry environment prior to use to minimize moisture acquisition.