In my romantic suspense series for Dragonblade Publishing, in several of the books, I mention individuals with broken limbs, as well as have my heroes attempt to make a mold of a prominent footprint found in book 5. Lord Benjamin Thompson from book 4, who initially trained as a surgeon, advises them to use resin, wax, and gypsum, but was that the going mixture.

Early attempts at using Plaster of Paris (gypsum-based) date back thousands of years, with evidence found in Egyptian pyramids and ancient construction, where it was valued for molding and fire resistance. In the 19th century, it was famously adopted for orthopedic casts, initially using “plâtre coulé” (heavy wooden boxes) in Europe, and later in bandages perfected by Antonius Mathijsen in 1852. 

Early Medical and Technical Uses

• Early Orthopedic Casting (c. 1800s): Before 1852, practitioners used a technique where limbs were placed in wooden containers filled with plaster. This method, known as plâtre coulé, was heavy and limited patient mobility, prompting searches for better methods.
• The Bandage Method (1852): Dutch surgeon Antonius Mathijsen revolutionized early adoption by using cotton bandages impregnated with dry, powdered plaster of Paris, which only needed to be moistened to set.
• Archaeological Preservation (1860s): Giuseppe Fiorelli, at Pompeii, used plaster injected into cavities in volcanic ash to create casts of the bodies of victims.
• Sculpture (18th/19th Century): Artists like John Flaxman (1755–1826) were pioneers in consistently using plaster for models and casts. 

Composition and Challenges

• Material Origin: It was derived from gypsum mined in Montmartre, Paris.
• Rapid Setting: Early mixtures set very rapidly. To manage this in artistic or repair work, mixtures sometimes included additives like glue.
• Initial Failures: Before the standardization of, and success with, the plaster bandage, attempts to use starch, wax, or clay to immobilize limbs often failed. 

Early applications were, therefore, a transition from heavy, constructive molding to lighter, more versatile, and, in medicine, more functional cast-based immobilization.