The Body Worlds exhibitions, featuring human bodies preserved by Gunther von Hagens, gave people around the world the chance to see the effects of his patented plastination process for themselves. The durability of the specimens, and the well-preserved color and form, made for remarkable viewing and included a few spectacular quasi-artistic innovations. So what exactly is plastination, and how does it work to permanently preserve flesh and bone?
The simple answer lies in taking food away from bacteria and other microorganisms that threaten the body, then reinforcing the cells and sealing them off from this food with another substance. Specifically, plastination is the process of removing water and fat from tissue and replacing it with polymers (molecules composed of many repeating units, like plastic and silicone). Because the microogranisms that cause decay need water and fat in order to survive, removing them completely will stop decomposition.
In order to be effective, the process of plastination needs to be done in four separate steps. First, the sample is chemically “fixed” in a formaldehyde solution to keep it from decaying while the work is being done and help preserve its original shape.
Next, the sample is placed in acetone, a solvent that evaporates easily, and cooled. In these conditions, the acetone pulls the water out of each cell and replaces it. This is the best way to ensure that absolutely no water is left in the sample, and also is a necessary intermediary, because the polymers used in plastination are incompatible with water.
After that, the sample is placed in a bath of the polymer that is being used. Believe it or not, silicone, epoxy resin, and polyester can all be used depending on the desired outcome. Each material will effect the color, transparency, and texture of the sample. The polymer bath is then put in a vacuum chamber, which causes the acetone to boil. As it vaporizes, a vacuum pulls the polymer into its place. This is the key to filling every single cell with the polymer, which will ensure that no decay can take place and the sample will keep its original shape.
The final step involves positioning the sample into its final shape and then “curing” it, which means hardening the polymer chains and turning them from liquid to solid. This can be done with ultraviolet light, heat, or certain gases, depending on the type of polymer used.
After much work (it was reported that the preparation of each body in Bodyworks took 1500 hours), the end result is a shaped, hardened sample, called a “plastinate,” which will not mold or decay. This ingenious process has already been adopted by some medical and veterinary schools, and may be a great asset in the future for teachers and students of anatomy.