What sort of isinglass was used to preserve eggs?

Isinglass used to preserve eggs typically refers to a form of Gelatin derived from the swim bladders of fish, particularly sturgeon. It was traditionally used in a process where the isinglass was dissolved in water to create a solution that coated the eggs, helping to seal them and prevent spoilage. This method not only preserved the eggs but also allowed them to retain their quality for longer periods. Isinglass was favored due to its natural properties and effectiveness in food preservation.