When a body is cremated, it's heated intensely -- at 1,800 degrees Fahrenheit or higher -- in a retort, or ovenlike device, until it's reduced to ash and bone fragments
Any pacemakers must be removed from the body first, since those devices can explode and damage the cremation chamber. And because the process is obviously irreversible and destroys DNA and other evidence, most state laws impose a waiting period of 24 to 48 hours from the time of death until cremation may begin.
The entire process takes from two to three hours, depending on the size of the body and type and temperature of the retort. The resulting cremains weigh from three to nine pounds -- again, depending on the size of the body.
Larger bone fragments within the cremains are usually pulverized before being gathered and returned to a designated person, usually a family member or close friend of the deceased. The cremains can then be placed in an urn or other container to be buried, stored, or scattered over land or water.
The process is conducted at a crematorium, which may be part of a chapel, funeral home, cemetery, or an independent facility. Laws in all states prohibit the operators there from cremating more than one body at a time. But as a precautionary check on this, most facilities will allow survivors to appoint a person to witness the cremation process. Some religions include this witnessing practice as one of their end-of-life customs.