When considering cremation, a common question arises about what precisely happens to bones, often leading to the misconception that they simply burn away to ash. The process is more intricate than simple combustion, involving a scientific transformation rather than complete incineration of the skeletal structure. Understanding this distinction clarifies the nature of cremated remains.
The Transformation of Bone During Cremation
Cremation occurs within specialized chambers, or retorts, where temperatures range between 1,400 to 1,800 degrees Fahrenheit (760-980°C). This intense heat causes the body’s organic matter, including soft tissues, to vaporize and oxidize. The bones, which are primarily composed of calcium phosphate, undergo a process called calcination.
During calcination, the high temperatures remove all moisture and consume the collagen and other organic compounds within the bone. This leaves behind brittle, inorganic mineral fragments. Bones do not “burn” to ash in the same way wood burns; instead, they are reduced to a fragile, porous state through this chemical and physical alteration.
Understanding Cremated Remains
The material received after cremation is not true ash, but rather bone fragments that have been reduced and processed. These cremated remains are primarily composed of dry calcium phosphates, along with minor minerals like salts of sodium and potassium. After the cremation chamber cools, these remaining bone fragments are collected.
These fragments then undergo a pulverization process, using a machine called a cremulator, to achieve a uniform, sand-like consistency. This step ensures the remains are fine and consistent. The resulting material can range in color, appearing white or grayish, depending on the temperature reached and the individual’s bone composition.
Variables Affecting the Cremation Process
Several factors can influence the cremation process and the appearance of the final remains. An individual’s body composition, particularly bone density and overall size, can affect the duration and efficiency of the process. Larger or denser bones may require slightly longer exposure to the high temperatures.
Medical devices also play a role; pacemakers and other battery-operated implants must be removed prior to cremation to prevent explosions. While larger metal implants like titanium hip replacements do not melt at cremation temperatures, they are removed from the remains after the process, before pulverization, to prevent damage to equipment. The specific crematory equipment used, along with the precise temperature and duration, contributes to the overall outcome.