The body is first placed in a combustible casket or container prior to going into the cremation chamber. (Some states do not require the body to be placed in a container; in this case the body may be wrapped in a shroud instead). The cremation chamber is preheated to a set temperature between 1400 and 1800 degrees. This temperature will be maintained throughout the cremation process.
After the cremation chamber has been fully heated, the container with the body inside is quickly transferred into the heated chamber through a mechanized door. Inside the cremation chamber, the body is constantly exposed to extremely high temperatures from open flames generated by a furnace. It usually takes somewhere between 2 to 3 hours to cremate a body completely.
During the cremation process, the container holding the body burns first. Then the heat from the flames dries the body, burns the skin and hair, contracts and chars the muscles, and vaporizes the soft tissues.
The heat then calcifies the bones into crumbly mineral fragments that resemble dry bone. The cremation process also produces gases as the body is reduced to its basic elements. The entire corpse is eventually reduced to skeletal remains and bone fragments, which are collected in a tray or pan and allowed to cool down. Once cooled, the bone fragments are processed or ground to a consistent granular form commonly called “cremated remains” or “ashes,” and are then returned to the family in either a temporary container or an urn.
Some non-organic fragments, such as dental work, dental gold, surgical screws, prostheses, implants, etc. will also remain. Metal fragments such as hinges, screws, etc. from the container may also be mixed in with the cremated remains. These metal fragments are removed from the cremated remains using a magnet, and are disposed of in accordance with local laws.