Goldbeater’s skin is the processed outer membrane of the intestine of an animal, typically an ox, valued for its strength against tearing.
Usage of Goldbeater’s skin:
- It is used in Goldbeater’s skin test for tannins.
- Traditionally, it is used in the repair of manuscripts written on vellum.
- The intestines, having been cut into sections and hosed clean of offal, arrived in the lab filling two five gallon plastic pails. A considerable quantity of mucous was present, and there was some blood. Literature concerning the manufacture of sausage casings from hog intestines indicated that salt was used to remove blood from these; so approximately one pound of salt was added to each five gallon bucket of ox intestines, and the buckets were closed.
- After a day the buckets were reopened and the intestines were examined and found to be substantially free of blood. The mucous in the intestines had not been idle during this time, anyone lay in a supply of clove oil or Lysol spray disinfectant as well as a good tight-fitting mask with fresh filters .
- Begin separating the membrane from the wall of the intestine by peeling apart the ridge of fat which runs alongside. Once started, the membrane peels fairly easily until there is a narrowing or turn to the intestine, or, until the fatty ridge comes to an end. Some of the pieces removed were only a few inches long while others were nearly two feet long.
- The membranes were rinsed in running water as the fat was pulled or scraped off, and then put in water to soak. Since ox intestine are in fairly short supply it was necessary to devise a method for stretching and drying the membranes with the least amount of waste. As it dried, the membrane tightened up and became clear. When the tension is released by cutting the membrane free of the drying rack, it shrinks slightly and becomes somewhat wrinkled, but this may be prevented by treating it with a light application of surgical jelly.