The actual process of cremation usually lasts 1-2 hours. The coffin is placed within the retort (the chamber within the cremator) and is subjected to heat of between 870 to 980°C. Most of the soft organs and tissue simply evaporate as they are subjected to such extreme heat. The gases get discharged through the chimney.
What is left after the cremation process is basically dry bone fragments and the quantity of these usually vary from 2kg to 3kg depending on the deceased size. The dry bone fragments are then removed from the retort and put through a cremulator. This device uses a grinding or rotating mechanism to turn the dry bone fragments into cremains (a technical term which combines the words cremation and remains) which take the appearance of grains of sand. (In some countries, like Japan, the cremulator is not used, but the families obtain the remains as they are – dry bone fragments). The “ashes” are then placed in a container, most usually an urn, and it is then up to the family to decide what to do with them. The ashes can stay in the urn and be displayed or scattered in variety of ways or fashions – (see Options for Ashes section).
More information on the cremation process as well as a helpful video.