Mummification in Ancient Egypt: A Timeline
The Egyptians made mummies for over 3,000 years, and they made many improvements (and non-improvements) so there are literally hundreds (if not thousands) of ways that Egyptians used to make mummies. You may have read that ancient Egyptians used natron (a natural salt, composed of sodium carbonate and sodium bicarbonate with traces of sodium chloride and sodium sulfate) to dry and preserve their dead. This is true--but only for part of the 3,000 years.
Because their mummy-making process evolved over a long time span, there wasn't just one to make a mummy--and every technique the Egyptians tried didn't produce a mummy (perhaps all they got was a bundle of bones, such as this early burial shown in the photo). By the time that the mummymakers perfected their craft around the 19th Dynasty, successful mummymaking was generally a three-part process:
removing internal organs
protecting dried remains
But this process varied considerably depending on the time period, the mummymaker, the wealth of the family, and other factors.
Very few mummies have been found from this period. The ones that have been recovered are naturally dried by the sun.
Very few mummies have been found from this period, but linen and plaster were important components. An examination of one Old Kingdom body revealed that the limbs were wrapped separately; altogether sixteen layers of linen were wound around the body. Often plaster was applied to the bandages to create a kind of "mummy sculpture." Sometimes a separate layer of plaster was added as a final layer, which created an even more statue-like look. The face would be painted onto the linen/plaster.
During the 4th Dynasty, internal organs were apparently removed for the first time. The abdomen was then packed with linen. The plaster sculpture look was generally stopped by the end of the 6th Dynasty or the beginning of the 7th Dynasty, though later examples are known, especially one in the 11th Dynasty. Sometimes rather than linen/plaster, linen/resin was used (with padding beneath with bandages); the face was then painted green (the color of resurrection, according to Egyptologist Joyce Tyldesley). Old Kingdom mummies might also be dressed in linen clothes (worn over the the wrappings). The plaster and resin mummies looked great, but produced terrible mummy results--underneath the wrappings, the mummies rotted from the moisture trapped inside.
During this time period, many different methods of mummification were used. Mummymakers learned to remove internal organs, but not necessarily all of the main four (that were eventually removed): liver, lungs, stomach, and intestines. The heart was almost always left in the body, but there are examples of its removal and replacement (after wrapping it with linen) inside the body. The body's face was no longer painted; instead, a funerary mask was placed over the mummy's head. Some researchers suspect that one (more unusual) method of making mummies used during this a part of this time period was cedar oil enemas (strange but true), which seems to have been used at least in some mummies during the 11th Dynasty. Rather than cutting the body open to remove internal organs, mummymakers seem to have injected cedar-oil/ turpentine into the rectum; this substance would help dissolve (at least partially) the internal organs. But this method would never have been used on important people; it may well have been an economy measure.
During this time period, royal mummymakers almost always removed the brain, removed the four internal organs (they were washed and dried, painted with resin, and wrapped in linen), and coated the body with lots of resin. Sometimes when they removed the lungs, they may have accidentally removed the heart--they wrapped it up and returned it to the body. After drying the body with natron (and most likely changing the natron whenever it got moist), they would fill the body with resin-soaked linen to provide a natural shape and inhibit insects from settling in. Other non-royal mummies made during the New Kingdom show that, although the brain and the internal organs were not removed, they were well-wrapped. At least one non-royal New Kingdom mummy was also coated in beeswax possibly to help with preservation.
Third Intermediate Period
The best royal mummymaking methods are found in the 21st Dynasty. At that time, they did their best to make a mummy as real and lifelike as possible. They removed internal organs through an incision in the abdomen (and then placed them back within the body)--then covered it with a metal plate with the design of an eye." They made numerous other incisions (apparently between five and seventeen cuts) in the skin so that the body could be padded realistically. The abdomen, the back, and the neck would be padded out (often with linen, sawdust, sand, and/or mud); so would arms, legs, buttocks, and thighs. They often placed wax over the eyelids and plugged the nose and ears with wax or linen as well. After drying and packing, the body would be painted next (red = men; yellow = women); eyes would be replaced with glass, stone, or painted linen. The entire body would then be coated with hot resin and bandaged (a 10-15 day process for the bandaging alone). Of course, this was the best method of making mummies; not everyone had the resources required for such treatment.
From the 22nd Dynasty on, mummymaking techniques began to decline. More and more people wanted to become mummies upon death; mummymakers began to take many shortcuts-- except in their bandaging techniques (which are extraordinary). Mummymakers used less stuffing and more molten resin which tended to turn the mummies dark and heavy. Inside, under the bandages, the bodies were not in particularly good condition. Sometimes bodies were mixed up and combined (accidentally) so that scientists have found parts or two or more people wrapped together sometimes. Internal organs were placed in canopic jars again during the 26th Dynasty. In succeeding dynasties, wrapped internal organs were placed between the mummy's legs but "dummy" canopic jars (they were empty) were used for symbolic purposes.
A Final Note
Egyptian mummies weighed very little--at least once they were re-discovered. One mummy from the Royal Ontario Museum in Canada, with linen wrappings removed, weighed just 5.13 kilograms (about 11 pounds or so). Of course, if the wrappings were still on it might weigh a good bit more, especially if resin or amulets were embedded in the linen--or if the wrappings were plastered with stucco.
Of course, you can always experiment by making your own mummy.