A consideration of crematories, both old and new, must be made to determine the functionability of the German Kremas at accomplishing their attributed tasks.
Cremation of the dead is not a new concept. It has been practiced by many cultures for many centuries. Although practiced several thousand years ago, it was frowned upon by the Catholic Church and not practiced recently until the Church relaxed its opposition in the later part of the 18th century.
Cremation was forbidden by Orthodox Judaism. By the early 1800's Europe was again practicing cremation on a limited basis. It becomes advantageous to control disease, free up much needed land in crowded areas and eliminate the need for storing corpses in winter when the ground is frozen. Europe's early crematories were coal or coke fired furnaces.
The oven or furnace which is used to cremate corpses is properly termed a retort. Early retorts were merely ovens which cooked all the moisture out of the corpse and reduced it to ash. Bones cannot be burned and must be pulverized, even today. The early mortar and pestle has been replaced by a crushing machine, however. Modern retorts are mostly gas fired, although some are still supplied for oil. None are still fired by coke or coal in the United States or Canada.
Earlier retorts were simply a drying or baking kiln and simply dried the human remains. Modern retorts of brick-lined steel actually blow fire from a nozzle onto the remains setting them afire, causing combustion and rapid burning. Modern retorts also have a second or afterburner for reburning all the pollutants in the combusted gaseous material. This second burner is a requirement set by the various state agencies responsible for air pollution. it should be noted that the human remains are not responsible for the pollution. It is caused entirely by the fossil fuels used. An electric retort, although cost prohibitive to run, would have no pollutants.
These modern retorts or crematories burn at a temperature of 2000+ degrees Fahrenheit, with an afterburner temperature of 1600 degrees Fahrenheit. This high temperature causes the body to combust and consume itself, allowing for the burner to be shut down. Wooden caskets and paper boxes are burned with the body, today, although not in the past, with no added time of burning due to the high temperature. Some European units are operated at a traditional lower temperature of 800 degrees Centigrade (1472 degrees Fahrenheit) and for a longer time period.
At 2000 degrees Fahrenheit or more with a 2500 cfm blowered air supply from the outside, modern retorts will cremate one corpse in 1.25 hours. Theoretically, this is 19.2 in a 24 hour time period. Factory recommendation for normal operation and sustained use allows for three (3) or less cremations per day. Older, oil, coal and coke furnaces with forced air (but no direct flame application) normally took 3.5 to 4 hours for each corpse. Theoretically, this could allow for 6.8 corpses in a 24 hour period at a maximum. Normal operation permits a maximum of three (3) cremations in a 24 hour time period. These computations are based on 1 corpse per retort per cremation. These modern retorts are of all steel construction and lined with high quality refractory brick. The fuel is pumped directly to the retort and all controls are electric and automatic. The coal and coke fired furnaces did not burn at an even temperature (approximately 1600 degrees Fahrenheit max.) and had to be constantly fed fuel by hand and dampered up and down. Since there was no direct application of flame to the corpse, the blower only fanned the flames and increased the temperature of the kiln. This crude mode of operation probably produced an average temperature of about 1400 degrees Fahrenheit.
The crematories utilized at the inspected German facilities were of the older type. They were constructed of red brick and mortar and lined with a refractory brick. All of the ovens had multiple retorts, some were blowered (although none had direct combustion), none had afterburners and all were coke fired except one facility no longer in existence at Majdanek. None of the retorts inspected and examined at all of the locations were designed for multiple corpse incineration. It should be noted that unless specifically designed for a greater bone to flesh to heat ratio, the retort will not consume the materials placed within it. Theoretical and real-time estimated maximum 24 hour outputs, based on one (1) corpse per retort per cremation are found in Table II.